Physics Book - User contributions [en]

Semiconductor Devices

2018-11-26T04:59:02Z

Jbuehler3:

Last Edited by Joey Buehler (Fall 2018)

Allison Youngsman 12/2/15

'''Claimed by Michael Eden (Fall 2016)'''

'''edited by Eric Lee (Fall 2016)'''

===Semiconductor Devices===

Semiconductor devices are electronic components with the electronic properties of semiconductors. Silicon, germanium, gallium arsenide, organic semiconductors are among the most common semiconductors used in these devices. Semiconductors are materials that are neither good conductors or good insulators. Due to low cost, reliability, and compactness, semiconductors are used for a wide range of applications. They also have a wide range of current and voltage handling capabilities, contributing to their suitability for a number of operations. They are commonly found in power devices, optical sensors, and light emitters. Perhaps more importantly, they are readily integrated into microelectronic uses as key elements for the majority of electronic systems, including communications, consumer, data-processing, and industrial-control equipment.

[[File:Intelthing.jpg|frame|border|right|A raw board with many transistors in it!]]
[[File:transistor.png|frame|none|left|An fully built integrated circuit.]]

==The Main Idea==

Semiconductors work by using the electric properties of the p-n junction that makes up a diode. The junction is formed through a process called doping. Doping involves turning silicon into a conductor by changing the behavior of its electrons. In n-type doping, a phosphorus/arsenic impurity is introduced so that the valence will have free electrons to allow a electric current to flow. Since extra electrons are negative in charge, this type of doping is called n-type doping referred to by "n" in the p-n junction. In the p-type doping, a boron/gallium impurity is introduced to the silicon lattice so the valence will have an empty electron orbital. Because the empty area implies the absence of an electron and thus creates a positive charge, "p" was assigned as the name of the doping type.

[[File:n-type.gif|frame|border|right|N-Type Material]]

[[File:p-type.png|frame|none|left|P-Type Material]]

The two most useful forms of semiconductor devices are diodes and transistors. Diodes are the simplest semiconductor device, which conducts current easily in one direction but conducts almost no current in the other direction. These are made by joining two pieces of semiconducting material,a junction called a "p-n" junction. One of the pieces contains a small amount of boron and the other contains a small amount of phosphorus. Transistors are constructed through two semiconducting junctions, or "p-n" junctions. These are the most common elements in digital circuits. The conductivity of these semiconductors can be controlled by introduction of an electric or magnetic field, by exposure to light or heat, or by mechanical deformation of a doped monocrystalline grid. Due to this, semiconductors are extremely useful and can be altered to fit specific purposes.

===A Mathematical Model===

Semiconductors operate based on the concept of thermal energy exciting electrons and causing them to jump to the next higher (unoccupied) energy band.
These electrons can pick up energy (and drift speed) from an applied electric field. The filled energy band is called the “valence” band, and the nearly unoccupied higher energy band is called the “conduction” band. The number of electrons excited into the conduction band is proportional to a value called the Boltzmann constant, equivalent to the value:
<math>
e^{-E_{\text{gap}} / k_B T}
</math>.
Therefore, high conductivity (corrosponding to a favorable Boltzmann factor) can be calculated according to
<math>
T = 2 \pi \sqrt{\frac{m}{k}}
</math>,
where <math>m</math> is the mass of the object in kilograms, <math>k</math> is the spring constant, and <math>T</math> is the period of oscillation in seconds. In addition, the total conventional current in a semiconductor can be calculated, according to the equation
<math>
I = e n_n A u_n E + e n_p A u_p E
</math>.

===A Conceptual Model===
The following diagram demonstrates how electron excitement in semiconductors works. Semiconductors are materials with small band gaps between the valence band and conduction bands. As you can see, a small amount of thermal energy is needed to promote an electron to the conduction band in a semiconductor.

[[File:conceptual.png|frame|none|left|A Conceptual Model of the Semiconductor]]

==History==
'''1874'''
Ferdinand Braun discovers that current flows freely in only one direction when a metal point and a galena crystal are put together.

'''1901'''
Jagadis Bose takes ownership of the discovery of the semiconductor crystal for detecting radio waves.

'''1940'''
Russell Ohl discovers the p-n junction.

'''1940s'''
Semiconductors were used only as two-terminal devices, such as rectifiers and photodiodes. They were most commonly used as detectors in radios, through devices called "cat's whiskers". During the era of WWII, researchers worked with semiconductors and cat's whiskers to make more effective diodes.

'''1947'''
William Shockley and John Bardeen worked together to create a triode-like semiconductor: the first transistor. They realized that if there were some way to control the flow of the electrons from the emitter to the collector of this newly discovered diode, an amplifier could be built.The first transistor was officially created on the 23rd of December, 1947.

'''1956'''
John Bardeen, William Shockley, and another researcher named Walter Houser Brattain were credited for the invention and awarded a Nobel Prize for physics in 1956 for their work. After this, the utilization of semiconductors soon advanced to even more complicated applications.

'''1960s'''
In the late 1960s, transistors moved from being germanium based to silicon based. Gordon K Teal was most responsible for this advancement, and his company, Texas Instruments, profited greatly. Portable radios are just one popular invention that benefited from silicon based semiconductors. Now, silicon based semiconductors constitute more than 95 percent of all semiconductor hardware sold worldwide.

'''1970s'''
Silicon technology is modernized and the race to fit all semiconductor processor technology into one chip is most active.

'''2000'''
Nobel Prize in physics awarded to Zhores I. Alferov and Herbert Kroemer for developing semiconductor heterostructures used in high-speed- and opto-electronics and half to Jack S. Kilby "for his part in the invention of the integrated circuit."

[[File:transistorwork.png|frame|none|none|John Bardeen, William Shockley, and Walter Houser Brattain, winners of the Nobel Prize for their invention of the transistor, are pictured above.]]

===Connectedness===

Semiconductors are crucial to modern technology, and are used for memory storage as well as so many other technological innovations. This technology is used every day by millions of people for thousands of different applications. Most people in the world have used semiconductors in one way or another, even if they weren't aware of it. It is specifically connected to the major of Biomedical Engineering through memory storage and the complex computer programs used every day to conduct business and create simulations for the furthering of biomedical research. All industrial applications of semiconductors are very applicable, from amplifiers to transistors to silicon disks. Without semiconductors, much of the technology that the general population relies on today would not be possible.

Semiconductors are used in essentially every part of this technological and electronically-dependent world we live in today. They have both conductor and insulator properties and includes all of the metal we see in wires. Computers, phones, and other electronic devices all use semiconductors to fulfill their functions such as communication and efficiency. The most important aspect of semiconductors is utilization, which is shown through the use of switches. Inside electronic devices, the switches exist in extremely large numbers, which is why electronic devices process information in an incredible speed with surprising efficiency.

Semiconductors are connected to chemical engineering largely through their industrial creation. The process of depositing each layer of material onto the wafer is a chemical process controlled by deposition of gaseous metals onto the wafer. There are an incredible variety of steps from material preparation to packaging which can be optimized by an eager chemical engineer.

==Types of Semiconductors==

===Diodes===

[[File:Diode_current_wiki.png|314px|thumb|right|top|IV Characteristic of a Diode]]

Diodes are really great! In a simple sense, they can give you a "point of no return" in your circuit (but they can actually do much more than that).
Three interesting things should be observed from the IV characteristic shown to the right:

# For small positive voltages and above, the diode does not limit the current (the line is almost vertical)!
# For small to larger negative voltages, the diode resists current (the line is almost flat).
# For a large negative voltage (the breakdown voltage) the diode gives up (no one is perfect).

We can formally define this line with the Shockley Diode Equation, which formalizes this observation:

<math display="block">
I = I_S \left( e^{\frac{V_D}{n V_T}} - 1 \right)
</math> where

<math>I</math> is the diode current,

<math>I_S</math> is the reverse bias saturation current (or scale current),

<math>V_D</math> is the voltage across the diode,

<math>V_T</math> is the thermal voltage, and

<math>n</math> is the ideality factor, (1 if the diode is ideal, greater than 1 if it is imperfect).

A great practical use for diodes is a rectifier:

[[File:Gratz.rectifier.en.svg|frame|border|center|Diodes groups the positive and negative signals together]]

This makes sure that when a positive voltage appears on either line, it is redirected to a single positive line, and the same for the negatives.
BAM! AC to DC, that's pretty easy, you can charge your phone with that.
In reality a capacitor is added in parallel with the load to try to smooth out the ripples.
A voltage regulator after the rectifying step is also a popular choice, depending on the needs of the application.

Another super useful application is that of a back up power supply: simply connect two supplies in parallel with the positive terminals buffered with diodes. The higher of the two voltages is always used and the transition between supplies is seamless.

===Zener Diodes===

Some diodes (Zener) are made to have small breakdown voltages.
Since during breakdown the IV curve is almost vertical (it's really an exponential), the current is independent (almost) from voltage.
You can then wire up a Zener diode in reverse to a point in the circuit, and it will accept as much current as it needs to to reach that
breakdown voltage. Because of this a great practical use for Zener diodes is a voltage regulator since the voltage is set when the diode is
manufactured and does not change greatly with a varying power supply.

===Bipolar Junction Transistors===

[[Image:BJT NPN symbol (case).svg|75px|thumb|NPN BJT]]
[[Image:BJT PNP symbol (case).svg|75px|thumb|PNP BJT]]

Shortly after the invention of the first transistor (which was OK), the BJT landed, which was the first transistor to be prolific in the field.
It was made using two alternating NP junctions as shown below:

[[File:NPN BJT (Planar) Cross-section.svg|frame|border|center|NPN BJT (Planar) Cross-section]]

Really transistors (and by extension all that is needed for a computer to be built) are amplifiers (OK, to build all computers you need an inverting amplifier, but one can be built using the BJT).
If one is used to thinking of them as an electrically-controlled switch, you can simply think of a switch as an amplifier with a gain of <math>\infty</math>.

A simple model of a BJT is a linear current-controlled current source, i.e. the base to emitter (B to E) current <math>I_{BE}</math> is proportional to
the collector to emitter (C to E) current <math>I_{CE}</math>. The proportionality constant <math>\beta</math> can be thought of as the "gain" of the
transistor. This gives a relationship of <math>I_{CE} = \beta I_{BE}</math>.

[[File:Current-Voltage relationship of BJT.png|thumb|right|Current-Voltage relationship of BJT]]

Sadly there is no source of infinite power, so the output to our amplifier tops off when it can't supply any more power.
This can be seen with the graph on the right.
The simple model then only works for the tiny linear part at the start of the graph, even so its not ''that'' linear.
The BJT proved to be power hungry, pretty non-linear and sensitive to the environment (temperature, etc.).
These growing pains lead to a new development, called the MOSFET.

===MOSFETs===

MOSFETs are the coolest, they are less power-hungy and easier to work with when compared to BJTs.
Instead of having a current control, which uses power and gets the control and the output signal coupled together,
a MOSFET's output is controlled by the electric Field (the F in MOSFET) the control signal creates on one of the plates of the MOSFET.
Since the control signal and the output are electrically disconnected (as you would see in a capacitor) there is much less power draw
from this type of transistor.

We can see how linear this thing is with its IV characteristic: <math>I_D= \mu_n C_{ox}\frac{W}{L} \left( (V_{GS}-V_{th})V_{DS}-\frac{V_{DS}^2}{2} \right)</math>

Apart from the control signal <math>V_{DS}</math> and constants, the voltage across the output portion of the MOSFET is linearly related to the current!
This means that the MOSFET behaves like a voltage controlled resistor, and a resistor is something much easier to analyse and work with.

Most circuits with an enormous amount of transistors these days use primarily MOSFETs. BJTs are still useful for temperature and light sensing
applications.

==Industrial Semiconductor Fabrication==

Semiconductors are mass produced in specialized factories called foundries or fabs. The process consists of multiple chemical and photolithographic steps which add layers to a wafer usually made of silicon. The entire process usually takes around 2 months but it can last up to 4.

The semiconductor product is rated by the size of the chip's process gate length, where processes with smaller gate lengths are typically harder to make. There are 10-20 different sized chips being fabricated around the world as of 2018. There is an immense amount of attention and money being dedicated to improving semiconductor fabrication process efficiency.

[[File:feol.png|frame|none|left|Steps to fabricate a semiconductor device]]

==Examples==

===Simple===
[[File:Cat'swhiskerdetector.jpg]]

A simple application of a semiconductor would be the Cat's Whisker detector for radios, invented in the early 1900s.

===Moderate===
[[File:Opticallsensor.jpg]]

Optical sensors are moderately difficult applications of semiconductors. Optical sensors are electronic detectors that convert light into an electronic signal. They are used in many industrial and consumer applications. An example would include lamps that turn on automatically in response to darkness.

===Difficult===

[[File:Complicated_semiconductor.jpg]]

A very complicated application of a semiconductor is its use in modern cellular phone devices, such as its use here in the iPhone 6.

== See also ==

Related Wiki pages:

-Transformers

-Resistors and conductivity

-Superconductors

-Electric Fields

-Transformers from a physics standpoint

===Further reading===

Chabay, Sherwood. (n.d.). Matter and Interactions (4th ed., Vol. 2). Raleigh, North Carolina: Wiley.

Sze, S. (1981). Physics of semiconductor devices (2nd ed.). New York: Wiley.

===External links===

Wikipedia page about semiconductors:

https://en.wikipedia.org/wiki/Semiconductor_device

Encyclopedia entry about semiconductors, including the history of semiconductors:

http://www.britannica.com/technology/semiconductor-device

Information about Diodes:

https://en.wikipedia.org/wiki/Diode

Information about BJTs:

https://en.wikipedia.org/wiki/Bipolar_junction_transistor

Information about MOSFETs:

https://en.wikipedia.org/wiki/MOSFET

Semiconductor Device Fabrication

https://en.wikipedia.org/wiki/Semiconductor_device_fabrication

==References==
Brain, Marshall. "How Semiconductors Work." HowStuffWorks. N.p., 25 Apr. 2001. Web. 27 Nov. 2016.

Chabay, Sherwood. (n.d.). Matter and Interactions (4th ed., Vol. 2). Raleigh, North Carolina: Wiley.

Electronics and Semiconductor. (n.d.). Retrieved December 3, 2015, from http://www.plm.automation.siemens.com/en_us/electronics-semiconductor/devices/

Huculak, M. (2014, September 19). IPhone 6 and iPhone 6 Plus get teardown by iFixit • The Windows Site for Enthusiasts - Pureinfotech. Retrieved December 3, 2015, from http://pureinfotech.com/2014/09/19/iphone-6-iphone-6-plus-get-teardown-ifixit/

John Bardeen, William Shockley and Walter Brattain at Bell Labs, 1948. (n.d.). Retrieved December 3, 2015, from https://en.wikipedia.org/wiki/John_Bardeen#/media/File:Bardeen_Shockley_Brattain_1948.JPG

The Nobel Prize in Physics 1956. NobelPrize.org. Nobel Media AB 2018. Sun. 25 Nov 2018. <https://www.nobelprize.org/prizes/physics/1956/summary/>

The Nobel Prize in Physics 2000. NobelPrize.org. Nobel Media AB 2018. Sun. 25 Nov 2018. <https://www.nobelprize.org/prizes/physics/2000/summary/>

เซ็นเซอร์แสง (Optical Sensor) - Elec-Za.com. (2014, July 28). Retrieved December 3, 2015, from http://www.elec-za.com/เซ็นเซอร์แสง-optical-sensor/

Semiconductor device. (2015, November 30). Retrieved December 3, 2015, from https://en.wikipedia.org/wiki/Semiconductor_device

Semiconductor Fabrication. (25 November 2018). http://www.iue.tuwien.ac.at/phd/rovitto/node10.html

Shah, A. (2013, May 13). Intel loses ground as world's top semiconductor company, survey says. Retrieved December 3, 2015, from http://www.pcworld.com/article/2038645/intel-loses-ground-as-worlds-top-semiconductor-company-survey-says.html

Shaw, R. (2014, November 1). The cat's-whisker detector. Retrieved December 3, 2015, from http://rileyjshaw.com/blog/the-cat's-whisker-detector/

Sze, S. (2015, October 1). Semiconductor device | electronics. Retrieved December 3, 2015, from http://www.britannica.com/technology/semiconductor-device

Sze, S. (1981). Physics of semiconductor devices (2nd ed.). New York: Wiley.

"Timeline." Timeline | The Silicon Engine | Computer History Museum. The Silicon Engine, n.d. Web. 27 Nov. 2016.

[[Category:Simple Circuits]]

Semiconductor Devices

2018-11-26T04:55:28Z

Jbuehler3:

Last Edited by Joey Buehler (Fall 2018)

Allison Youngsman 12/2/15

'''Claimed by Michael Eden (Fall 2016)'''

'''edited by Eric Lee (Fall 2016)'''

===Semiconductor Devices===

Semiconductor devices are electronic components with the electronic properties of semiconductors. Silicon, germanium, gallium arsenide, organic semiconductors are among the most common semiconductors used in these devices. Semiconductors are materials that are neither good conductors or good insulators. Due to low cost, reliability, and compactness, semiconductors are used for a wide range of applications. They also have a wide range of current and voltage handling capabilities, contributing to their suitability for a number of operations. They are commonly found in power devices, optical sensors, and light emitters. Perhaps more importantly, they are readily integrated into microelectronic uses as key elements for the majority of electronic systems, including communications, consumer, data-processing, and industrial-control equipment.

[[File:Intelthing.jpg|frame|border|right|A raw board with many transistors in it!]]
[[File:transistor.png|frame|none|left|An fully built integrated circuit.]]

==The Main Idea==

Semiconductors work by using the electric properties of the p-n junction that makes up a diode. The junction is formed through a process called doping. Doping involves turning silicon into a conductor by changing the behavior of its electrons. In n-type doping, a phosphorus/arsenic impurity is introduced so that the valence will have free electrons to allow a electric current to flow. Since extra electrons are negative in charge, this type of doping is called n-type doping referred to by "n" in the p-n junction. In the p-type doping, a boron/gallium impurity is introduced to the silicon lattice so the valence will have an empty electron orbital. Because the empty area implies the absence of an electron and thus creates a positive charge, "p" was assigned as the name of the doping type.

[[File:n-type.gif|frame|border|right|N-Type Material]]

[[File:p-type.png|frame|none|left|P-Type Material]]

The two most useful forms of semiconductor devices are diodes and transistors. Diodes are the simplest semiconductor device, which conducts current easily in one direction but conducts almost no current in the other direction. These are made by joining two pieces of semiconducting material,a junction called a "p-n" junction. One of the pieces contains a small amount of boron and the other contains a small amount of phosphorus. Transistors are constructed through two semiconducting junctions, or "p-n" junctions. These are the most common elements in digital circuits. The conductivity of these semiconductors can be controlled by introduction of an electric or magnetic field, by exposure to light or heat, or by mechanical deformation of a doped monocrystalline grid. Due to this, semiconductors are extremely useful and can be altered to fit specific purposes.

===A Mathematical Model===

Semiconductors operate based on the concept of thermal energy exciting electrons and causing them to jump to the next higher (unoccupied) energy band.
These electrons can pick up energy (and drift speed) from an applied electric field. The filled energy band is called the “valence” band, and the nearly unoccupied higher energy band is called the “conduction” band. The number of electrons excited into the conduction band is proportional to a value called the Boltzmann constant, equivalent to the value:
<math>
e^{-E_{\text{gap}} / k_B T}
</math>.
Therefore, high conductivity (corrosponding to a favorable Boltzmann factor) can be calculated according to
<math>
T = 2 \pi \sqrt{\frac{m}{k}}
</math>,
where <math>m</math> is the mass of the object in kilograms, <math>k</math> is the spring constant, and <math>T</math> is the period of oscillation in seconds. In addition, the total conventional current in a semiconductor can be calculated, according to the equation
<math>
I = e n_n A u_n E + e n_p A u_p E
</math>.

===A Conceptual Model===
The following diagram demonstrates how electron excitement in semiconductors works. Semiconductors are materials with small band gaps between the valence band and conduction bands. As you can see, a small amount of thermal energy is needed to promote an electron to the conduction band in a semiconductor.

[[File:conceptual.png|frame|none|left|A Conceptual Model of the Semiconductor]]

==History==
'''1874'''
Ferdinand Braun discovers that current flows freely in only one direction when a metal point and a galena crystal are put together.

'''1901'''
Jagadis Bose takes ownership of the discovery of the semiconductor crystal for detecting radio waves.

'''1940'''
Russell Ohl discovers the p-n junction.

'''1940s'''
Semiconductors were used only as two-terminal devices, such as rectifiers and photodiodes. They were most commonly used as detectors in radios, through devices called "cat's whiskers". During the era of WWII, researchers worked with semiconductors and cat's whiskers to make more effective diodes.

'''1947'''
William Shockley and John Bardeen worked together to create a triode-like semiconductor: the first transistor. They realized that if there were some way to control the flow of the electrons from the emitter to the collector of this newly discovered diode, an amplifier could be built.The first transistor was officially created on the 23rd of December, 1947.

'''1956'''
John Bardeen, William Shockley, and another researcher named Walter Houser Brattain were credited for the invention and awarded a Nobel Prize for physics in 1956 for their work. After this, the utilization of semiconductors soon advanced to even more complicated applications.

'''1960s'''
In the late 1960s, transistors moved from being germanium based to silicon based. Gordon K Teal was most responsible for this advancement, and his company, Texas Instruments, profited greatly. Portable radios are just one popular invention that benefited from silicon based semiconductors. Now, silicon based semiconductors constitute more than 95 percent of all semiconductor hardware sold worldwide.

'''1970s'''
Silicon technology is modernized and the race to fit all semiconductor processor technology into one chip is most active.

[[File:transistorwork.png|frame|none|none|John Bardeen, William Shockley, and Walter Houser Brattain, winners of the Nobel Prize for their invention of the transistor, are pictured above.]]

===Connectedness===

Semiconductors are crucial to modern technology, and are used for memory storage as well as so many other technological innovations. This technology is used every day by millions of people for thousands of different applications. Most people in the world have used semiconductors in one way or another, even if they weren't aware of it. It is specifically connected to the major of Biomedical Engineering through memory storage and the complex computer programs used every day to conduct business and create simulations for the furthering of biomedical research. All industrial applications of semiconductors are very applicable, from amplifiers to transistors to silicon disks. Without semiconductors, much of the technology that the general population relies on today would not be possible.

Semiconductors are used in essentially every part of this technological and electronically-dependent world we live in today. They have both conductor and insulator properties and includes all of the metal we see in wires. Computers, phones, and other electronic devices all use semiconductors to fulfill their functions such as communication and efficiency. The most important aspect of semiconductors is utilization, which is shown through the use of switches. Inside electronic devices, the switches exist in extremely large numbers, which is why electronic devices process information in an incredible speed with surprising efficiency.

Semiconductors are connected to chemical engineering largely through their industrial creation. The process of depositing each layer of material onto the wafer is a chemical process controlled by deposition of gaseous metals onto the wafer. There are an incredible variety of steps from material preparation to packaging which can be optimized by an eager chemical engineer.

==Types of Semiconductors==

===Diodes===

[[File:Diode_current_wiki.png|314px|thumb|right|top|IV Characteristic of a Diode]]

Diodes are really great! In a simple sense, they can give you a "point of no return" in your circuit (but they can actually do much more than that).
Three interesting things should be observed from the IV characteristic shown to the right:

# For small positive voltages and above, the diode does not limit the current (the line is almost vertical)!
# For small to larger negative voltages, the diode resists current (the line is almost flat).
# For a large negative voltage (the breakdown voltage) the diode gives up (no one is perfect).

We can formally define this line with the Shockley Diode Equation, which formalizes this observation:

<math display="block">
I = I_S \left( e^{\frac{V_D}{n V_T}} - 1 \right)
</math> where

<math>I</math> is the diode current,

<math>I_S</math> is the reverse bias saturation current (or scale current),

<math>V_D</math> is the voltage across the diode,

<math>V_T</math> is the thermal voltage, and

<math>n</math> is the ideality factor, (1 if the diode is ideal, greater than 1 if it is imperfect).

A great practical use for diodes is a rectifier:

[[File:Gratz.rectifier.en.svg|frame|border|center|Diodes groups the positive and negative signals together]]

This makes sure that when a positive voltage appears on either line, it is redirected to a single positive line, and the same for the negatives.
BAM! AC to DC, that's pretty easy, you can charge your phone with that.
In reality a capacitor is added in parallel with the load to try to smooth out the ripples.
A voltage regulator after the rectifying step is also a popular choice, depending on the needs of the application.

Another super useful application is that of a back up power supply: simply connect two supplies in parallel with the positive terminals buffered with diodes. The higher of the two voltages is always used and the transition between supplies is seamless.

===Zener Diodes===

Some diodes (Zener) are made to have small breakdown voltages.
Since during breakdown the IV curve is almost vertical (it's really an exponential), the current is independent (almost) from voltage.
You can then wire up a Zener diode in reverse to a point in the circuit, and it will accept as much current as it needs to to reach that
breakdown voltage. Because of this a great practical use for Zener diodes is a voltage regulator since the voltage is set when the diode is
manufactured and does not change greatly with a varying power supply.

===Bipolar Junction Transistors===

[[Image:BJT NPN symbol (case).svg|75px|thumb|NPN BJT]]
[[Image:BJT PNP symbol (case).svg|75px|thumb|PNP BJT]]

Shortly after the invention of the first transistor (which was OK), the BJT landed, which was the first transistor to be prolific in the field.
It was made using two alternating NP junctions as shown below:

[[File:NPN BJT (Planar) Cross-section.svg|frame|border|center|NPN BJT (Planar) Cross-section]]

Really transistors (and by extension all that is needed for a computer to be built) are amplifiers (OK, to build all computers you need an inverting amplifier, but one can be built using the BJT).
If one is used to thinking of them as an electrically-controlled switch, you can simply think of a switch as an amplifier with a gain of <math>\infty</math>.

A simple model of a BJT is a linear current-controlled current source, i.e. the base to emitter (B to E) current <math>I_{BE}</math> is proportional to
the collector to emitter (C to E) current <math>I_{CE}</math>. The proportionality constant <math>\beta</math> can be thought of as the "gain" of the
transistor. This gives a relationship of <math>I_{CE} = \beta I_{BE}</math>.

[[File:Current-Voltage relationship of BJT.png|thumb|right|Current-Voltage relationship of BJT]]

Sadly there is no source of infinite power, so the output to our amplifier tops off when it can't supply any more power.
This can be seen with the graph on the right.
The simple model then only works for the tiny linear part at the start of the graph, even so its not ''that'' linear.
The BJT proved to be power hungry, pretty non-linear and sensitive to the environment (temperature, etc.).
These growing pains lead to a new development, called the MOSFET.

===MOSFETs===

MOSFETs are the coolest, they are less power-hungy and easier to work with when compared to BJTs.
Instead of having a current control, which uses power and gets the control and the output signal coupled together,
a MOSFET's output is controlled by the electric Field (the F in MOSFET) the control signal creates on one of the plates of the MOSFET.
Since the control signal and the output are electrically disconnected (as you would see in a capacitor) there is much less power draw
from this type of transistor.

We can see how linear this thing is with its IV characteristic: <math>I_D= \mu_n C_{ox}\frac{W}{L} \left( (V_{GS}-V_{th})V_{DS}-\frac{V_{DS}^2}{2} \right)</math>

Apart from the control signal <math>V_{DS}</math> and constants, the voltage across the output portion of the MOSFET is linearly related to the current!
This means that the MOSFET behaves like a voltage controlled resistor, and a resistor is something much easier to analyse and work with.

Most circuits with an enormous amount of transistors these days use primarily MOSFETs. BJTs are still useful for temperature and light sensing
applications.

==Industrial Semiconductor Fabrication==

Semiconductors are mass produced in specialized factories called foundries or fabs. The process consists of multiple chemical and photolithographic steps which add layers to a wafer usually made of silicon. The entire process usually takes around 2 months but it can last up to 4.

The semiconductor product is rated by the size of the chip's process gate length, where processes with smaller gate lengths are typically harder to make. There are 10-20 different sized chips being fabricated around the world as of 2018. There is an immense amount of attention and money being dedicated to improving semiconductor fabrication process efficiency.

[[File:feol.png|frame|none|left|Steps to fabricate a semiconductor device]]

==Examples==

===Simple===
[[File:Cat'swhiskerdetector.jpg]]

A simple application of a semiconductor would be the Cat's Whisker detector for radios, invented in the early 1900s.

===Moderate===
[[File:Opticallsensor.jpg]]

Optical sensors are moderately difficult applications of semiconductors. Optical sensors are electronic detectors that convert light into an electronic signal. They are used in many industrial and consumer applications. An example would include lamps that turn on automatically in response to darkness.

===Difficult===

[[File:Complicated_semiconductor.jpg]]

A very complicated application of a semiconductor is its use in modern cellular phone devices, such as its use here in the iPhone 6.

== See also ==

Related Wiki pages:

-Transformers

-Resistors and conductivity

-Superconductors

-Electric Fields

-Transformers from a physics standpoint

===Further reading===

Chabay, Sherwood. (n.d.). Matter and Interactions (4th ed., Vol. 2). Raleigh, North Carolina: Wiley.

Sze, S. (1981). Physics of semiconductor devices (2nd ed.). New York: Wiley.

===External links===

Wikipedia page about semiconductors:

https://en.wikipedia.org/wiki/Semiconductor_device

Encyclopedia entry about semiconductors, including the history of semiconductors:

http://www.britannica.com/technology/semiconductor-device

Information about Diodes:

https://en.wikipedia.org/wiki/Diode

Information about BJTs:

https://en.wikipedia.org/wiki/Bipolar_junction_transistor

Information about MOSFETs:

https://en.wikipedia.org/wiki/MOSFET

Semiconductor Device Fabrication

https://en.wikipedia.org/wiki/Semiconductor_device_fabrication

==References==
Brain, Marshall. "How Semiconductors Work." HowStuffWorks. N.p., 25 Apr. 2001. Web. 27 Nov. 2016.

Chabay, Sherwood. (n.d.). Matter and Interactions (4th ed., Vol. 2). Raleigh, North Carolina: Wiley.

Electronics and Semiconductor. (n.d.). Retrieved December 3, 2015, from http://www.plm.automation.siemens.com/en_us/electronics-semiconductor/devices/

Huculak, M. (2014, September 19). IPhone 6 and iPhone 6 Plus get teardown by iFixit • The Windows Site for Enthusiasts - Pureinfotech. Retrieved December 3, 2015, from http://pureinfotech.com/2014/09/19/iphone-6-iphone-6-plus-get-teardown-ifixit/

John Bardeen, William Shockley and Walter Brattain at Bell Labs, 1948. (n.d.). Retrieved December 3, 2015, from https://en.wikipedia.org/wiki/John_Bardeen#/media/File:Bardeen_Shockley_Brattain_1948.JPG

The Nobel Prize in Physics 1956. NobelPrize.org. Nobel Media AB 2018. Sun. 25 Nov 2018. <https://www.nobelprize.org/prizes/physics/1956/summary/>

The Nobel Prize in Physics 2000. NobelPrize.org. Nobel Media AB 2018. Sun. 25 Nov 2018. <https://www.nobelprize.org/prizes/physics/2000/summary/>

เซ็นเซอร์แสง (Optical Sensor) - Elec-Za.com. (2014, July 28). Retrieved December 3, 2015, from http://www.elec-za.com/เซ็นเซอร์แสง-optical-sensor/

Semiconductor device. (2015, November 30). Retrieved December 3, 2015, from https://en.wikipedia.org/wiki/Semiconductor_device

Semiconductor Fabrication. (25 November 2018). http://www.iue.tuwien.ac.at/phd/rovitto/node10.html

Shah, A. (2013, May 13). Intel loses ground as world's top semiconductor company, survey says. Retrieved December 3, 2015, from http://www.pcworld.com/article/2038645/intel-loses-ground-as-worlds-top-semiconductor-company-survey-says.html

Shaw, R. (2014, November 1). The cat's-whisker detector. Retrieved December 3, 2015, from http://rileyjshaw.com/blog/the-cat's-whisker-detector/

Sze, S. (2015, October 1). Semiconductor device | electronics. Retrieved December 3, 2015, from http://www.britannica.com/technology/semiconductor-device

Sze, S. (1981). Physics of semiconductor devices (2nd ed.). New York: Wiley.

"Timeline." Timeline | The Silicon Engine | Computer History Museum. The Silicon Engine, n.d. Web. 27 Nov. 2016.

[[Category:Simple Circuits]]

Semiconductor Devices

2018-11-26T04:47:31Z

Jbuehler3:

Last Edited by Joey Buehler (Fall 2018)

Allison Youngsman 12/2/15

'''Claimed by Michael Eden (Fall 2016)'''

'''edited by Eric Lee (Fall 2016)'''

===Semiconductor Devices===

Semiconductor devices are electronic components with the electronic properties of semiconductors. Silicon, germanium, gallium arsenide, organic semiconductors are among the most common semiconductors used in these devices. Semiconductors are materials that are neither good conductors or good insulators. Due to low cost, reliability, and compactness, semiconductors are used for a wide range of applications. They also have a wide range of current and voltage handling capabilities, contributing to their suitability for a number of operations. They are commonly found in power devices, optical sensors, and light emitters. Perhaps more importantly, they are readily integrated into microelectronic uses as key elements for the majority of electronic systems, including communications, consumer, data-processing, and industrial-control equipment.

[[File:Intelthing.jpg|frame|border|right|A raw board with many transistors in it!]]
[[File:transistor.png|frame|none|left|An fully built integrated circuit.]]

==The Main Idea==

Semiconductors work by using the electric properties of the p-n junction that makes up a diode. The junction is formed through a process called doping. Doping involves turning silicon into a conductor by changing the behavior of its electrons. In n-type doping, a phosphorus/arsenic impurity is introduced so that the valence will have free electrons to allow a electric current to flow. Since extra electrons are negative in charge, this type of doping is called n-type doping referred to by "n" in the p-n junction. In the p-type doping, a boron/gallium impurity is introduced to the silicon lattice so the valence will have an empty electron orbital. Because the empty area implies the absence of an electron and thus creates a positive charge, "p" was assigned as the name of the doping type.

[[File:n-type.gif|frame|border|right|N-Type Material]]

[[File:p-type.png|frame|none|left|P-Type Material]]

The two most useful forms of semiconductor devices are diodes and transistors. Diodes are the simplest semiconductor device, which conducts current easily in one direction but conducts almost no current in the other direction. These are made by joining two pieces of semiconducting material,a junction called a "p-n" junction. One of the pieces contains a small amount of boron and the other contains a small amount of phosphorus. Transistors are constructed through two semiconducting junctions, or "p-n" junctions. These are the most common elements in digital circuits. The conductivity of these semiconductors can be controlled by introduction of an electric or magnetic field, by exposure to light or heat, or by mechanical deformation of a doped monocrystalline grid. Due to this, semiconductors are extremely useful and can be altered to fit specific purposes.

===A Mathematical Model===

Semiconductors operate based on the concept of thermal energy exciting electrons and causing them to jump to the next higher (unoccupied) energy band.
These electrons can pick up energy (and drift speed) from an applied electric field. The filled energy band is called the “valence” band, and the nearly unoccupied higher energy band is called the “conduction” band. The number of electrons excited into the conduction band is proportional to a value called the Boltzmann constant, equivalent to the value:
<math>
e^{-E_{\text{gap}} / k_B T}
</math>.
Therefore, high conductivity (corrosponding to a favorable Boltzmann factor) can be calculated according to
<math>
T = 2 \pi \sqrt{\frac{m}{k}}
</math>,
where <math>m</math> is the mass of the object in kilograms, <math>k</math> is the spring constant, and <math>T</math> is the period of oscillation in seconds. In addition, the total conventional current in a semiconductor can be calculated, according to the equation
<math>
I = e n_n A u_n E + e n_p A u_p E
</math>.

===A Conceptual Model===
The following diagram demonstrates how electron excitement in semiconductors works. Semiconductors are materials with small band gaps between the valence band and conduction bands. As you can see, a small amount of thermal energy is needed to promote an electron to the conduction band in a semiconductor.

[[File:conceptual.png|frame|none|left|A Conceptual Model of the Semiconductor]]

==History==
'''1874'''
Ferdinand Braun discovers that current flows freely in only one direction when a metal point and a galena crystal are put together.

'''1901'''
Jagadis Bose takes ownership of the discovery of the semiconductor crystal for detecting radio waves.

'''1940'''
Russell Ohl discovers the p-n junction.

'''1940s'''
Semiconductors were used only as two-terminal devices, such as rectifiers and photodiodes. They were most commonly used as detectors in radios, through devices called "cat's whiskers". During the era of WWII, researchers worked with semiconductors and cat's whiskers to make more effective diodes.

'''1947'''
William Shockley and John Bardeen worked together to create a triode-like semiconductor: the first transistor. They realized that if there were some way to control the flow of the electrons from the emitter to the collector of this newly discovered diode, an amplifier could be built.The first transistor was officially created on the 23rd of December, 1947.

'''1956'''
John Bardeen, William Shockley, and another researcher named Walter Houser Brattain were credited for the invention and awarded a Nobel Prize for physics in 1956 for their work. After this, the utilization of semiconductors soon advanced to even more complicated applications.

'''1960s'''
In the late 1960s, transistors moved from being germanium based to silicon based. Gordon K Teal was most responsible for this advancement, and his company, Texas Instruments, profited greatly. Portable radios are just one popular invention that benefited from silicon based semiconductors. Now, silicon based semiconductors constitute more than 95 percent of all semiconductor hardware sold worldwide.

'''1970s'''
Silicon technology is modernized and the race to fit all semiconductor processor technology into one chip is most active.

[[File:transistorwork.png|frame|none|none|John Bardeen, William Shockley, and Walter Houser Brattain, winners of the Nobel Prize for their invention of the transistor, are pictured above.]]

===Connectedness===

Semiconductors are crucial to modern technology, and are used for memory storage as well as so many other technological innovations. This technology is used every day by millions of people for thousands of different applications. Most people in the world have used semiconductors in one way or another, even if they weren't aware of it. It is specifically connected to the major of Biomedical Engineering through memory storage and the complex computer programs used every day to conduct business and create simulations for the furthering of biomedical research. All industrial applications of semiconductors are very applicable, from amplifiers to transistors to silicon disks. Without semiconductors, much of the technology that the general population relies on today would not be possible.

Semiconductors are used in essentially every part of this technological and electronically-dependent world we live in today. They have both conductor and insulator properties and includes all of the metal we see in wires. Computers, phones, and other electronic devices all use semiconductors to fulfill their functions such as communication and efficiency. The most important aspect of semiconductors is utilization, which is shown through the use of switches. Inside electronic devices, the switches exist in extremely large numbers, which is why electronic devices process information in an incredible speed with surprising efficiency.

==Types of Semiconductors==

===Diodes===

[[File:Diode_current_wiki.png|314px|thumb|right|top|IV Characteristic of a Diode]]

Diodes are really great! In a simple sense, they can give you a "point of no return" in your circuit (but they can actually do much more than that).
Three interesting things should be observed from the IV characteristic shown to the right:

# For small positive voltages and above, the diode does not limit the current (the line is almost vertical)!
# For small to larger negative voltages, the diode resists current (the line is almost flat).
# For a large negative voltage (the breakdown voltage) the diode gives up (no one is perfect).

We can formally define this line with the Shockley Diode Equation, which formalizes this observation:

<math display="block">
I = I_S \left( e^{\frac{V_D}{n V_T}} - 1 \right)
</math> where

<math>I</math> is the diode current,

<math>I_S</math> is the reverse bias saturation current (or scale current),

<math>V_D</math> is the voltage across the diode,

<math>V_T</math> is the thermal voltage, and

<math>n</math> is the ideality factor, (1 if the diode is ideal, greater than 1 if it is imperfect).

A great practical use for diodes is a rectifier:

[[File:Gratz.rectifier.en.svg|frame|border|center|Diodes groups the positive and negative signals together]]

This makes sure that when a positive voltage appears on either line, it is redirected to a single positive line, and the same for the negatives.
BAM! AC to DC, that's pretty easy, you can charge your phone with that.
In reality a capacitor is added in parallel with the load to try to smooth out the ripples.
A voltage regulator after the rectifying step is also a popular choice, depending on the needs of the application.

Another super useful application is that of a back up power supply: simply connect two supplies in parallel with the positive terminals buffered with diodes. The higher of the two voltages is always used and the transition between supplies is seamless.

===Zener Diodes===

Some diodes (Zener) are made to have small breakdown voltages.
Since during breakdown the IV curve is almost vertical (it's really an exponential), the current is independent (almost) from voltage.
You can then wire up a Zener diode in reverse to a point in the circuit, and it will accept as much current as it needs to to reach that
breakdown voltage. Because of this a great practical use for Zener diodes is a voltage regulator since the voltage is set when the diode is
manufactured and does not change greatly with a varying power supply.

===Bipolar Junction Transistors===

[[Image:BJT NPN symbol (case).svg|75px|thumb|NPN BJT]]
[[Image:BJT PNP symbol (case).svg|75px|thumb|PNP BJT]]

Shortly after the invention of the first transistor (which was OK), the BJT landed, which was the first transistor to be prolific in the field.
It was made using two alternating NP junctions as shown below:

[[File:NPN BJT (Planar) Cross-section.svg|frame|border|center|NPN BJT (Planar) Cross-section]]

Really transistors (and by extension all that is needed for a computer to be built) are amplifiers (OK, to build all computers you need an inverting amplifier, but one can be built using the BJT).
If one is used to thinking of them as an electrically-controlled switch, you can simply think of a switch as an amplifier with a gain of <math>\infty</math>.

A simple model of a BJT is a linear current-controlled current source, i.e. the base to emitter (B to E) current <math>I_{BE}</math> is proportional to
the collector to emitter (C to E) current <math>I_{CE}</math>. The proportionality constant <math>\beta</math> can be thought of as the "gain" of the
transistor. This gives a relationship of <math>I_{CE} = \beta I_{BE}</math>.

[[File:Current-Voltage relationship of BJT.png|thumb|right|Current-Voltage relationship of BJT]]

Sadly there is no source of infinite power, so the output to our amplifier tops off when it can't supply any more power.
This can be seen with the graph on the right.
The simple model then only works for the tiny linear part at the start of the graph, even so its not ''that'' linear.
The BJT proved to be power hungry, pretty non-linear and sensitive to the environment (temperature, etc.).
These growing pains lead to a new development, called the MOSFET.

===MOSFETs===

MOSFETs are the coolest, they are less power-hungy and easier to work with when compared to BJTs.
Instead of having a current control, which uses power and gets the control and the output signal coupled together,
a MOSFET's output is controlled by the electric Field (the F in MOSFET) the control signal creates on one of the plates of the MOSFET.
Since the control signal and the output are electrically disconnected (as you would see in a capacitor) there is much less power draw
from this type of transistor.

We can see how linear this thing is with its IV characteristic: <math>I_D= \mu_n C_{ox}\frac{W}{L} \left( (V_{GS}-V_{th})V_{DS}-\frac{V_{DS}^2}{2} \right)</math>

Apart from the control signal <math>V_{DS}</math> and constants, the voltage across the output portion of the MOSFET is linearly related to the current!
This means that the MOSFET behaves like a voltage controlled resistor, and a resistor is something much easier to analyse and work with.

Most circuits with an enormous amount of transistors these days use primarily MOSFETs. BJTs are still useful for temperature and light sensing
applications.

==Industrial Semiconductor Fabrication==

Semiconductors are mass produced in specialized factories called foundries or fabs. The process consists of multiple chemical and photolithographic steps which add layers to a wafer usually made of silicon. The entire process usually takes around 2 months but it can last up to 4.

The semiconductor product is rated by the size of the chip's process gate length, where processes with smaller gate lengths are typically harder to make. There are 10-20 different sized chips being fabricated around the world as of 2018. There is an immense amount of attention and money being dedicated to improving semiconductor fabrication process efficiency.

[[File:feol.png|frame|none|left|Steps to fabricate a semiconductor device]]

==Examples==

===Simple===
[[File:Cat'swhiskerdetector.jpg]]

A simple application of a semiconductor would be the Cat's Whisker detector for radios, invented in the early 1900s.

===Moderate===
[[File:Opticallsensor.jpg]]

Optical sensors are moderately difficult applications of semiconductors. Optical sensors are electronic detectors that convert light into an electronic signal. They are used in many industrial and consumer applications. An example would include lamps that turn on automatically in response to darkness.

===Difficult===

[[File:Complicated_semiconductor.jpg]]

A very complicated application of a semiconductor is its use in modern cellular phone devices, such as its use here in the iPhone 6.

== See also ==

Related Wiki pages:

-Transformers

-Resistors and conductivity

-Superconductors

-Electric Fields

-Transformers from a physics standpoint

===Further reading===

Chabay, Sherwood. (n.d.). Matter and Interactions (4th ed., Vol. 2). Raleigh, North Carolina: Wiley.

Sze, S. (1981). Physics of semiconductor devices (2nd ed.). New York: Wiley.

===External links===

Wikipedia page about semiconductors:

https://en.wikipedia.org/wiki/Semiconductor_device

Encyclopedia entry about semiconductors, including the history of semiconductors:

http://www.britannica.com/technology/semiconductor-device

Information about Diodes:

https://en.wikipedia.org/wiki/Diode

Information about BJTs:

https://en.wikipedia.org/wiki/Bipolar_junction_transistor

Information about MOSFETs:

https://en.wikipedia.org/wiki/MOSFET

==References==
Brain, Marshall. "How Semiconductors Work." HowStuffWorks. N.p., 25 Apr. 2001. Web. 27 Nov. 2016.

Chabay, Sherwood. (n.d.). Matter and Interactions (4th ed., Vol. 2). Raleigh, North Carolina: Wiley.

Electronics and Semiconductor. (n.d.). Retrieved December 3, 2015, from http://www.plm.automation.siemens.com/en_us/electronics-semiconductor/devices/

Huculak, M. (2014, September 19). IPhone 6 and iPhone 6 Plus get teardown by iFixit • The Windows Site for Enthusiasts - Pureinfotech. Retrieved December 3, 2015, from http://pureinfotech.com/2014/09/19/iphone-6-iphone-6-plus-get-teardown-ifixit/

John Bardeen, William Shockley and Walter Brattain at Bell Labs, 1948. (n.d.). Retrieved December 3, 2015, from https://en.wikipedia.org/wiki/John_Bardeen#/media/File:Bardeen_Shockley_Brattain_1948.JPG

เซ็นเซอร์แสง (Optical Sensor) - Elec-Za.com. (2014, July 28). Retrieved December 3, 2015, from http://www.elec-za.com/เซ็นเซอร์แสง-optical-sensor/

Semiconductor device. (2015, November 30). Retrieved December 3, 2015, from https://en.wikipedia.org/wiki/Semiconductor_device

Shah, A. (2013, May 13). Intel loses ground as world's top semiconductor company, survey says. Retrieved December 3, 2015, from http://www.pcworld.com/article/2038645/intel-loses-ground-as-worlds-top-semiconductor-company-survey-says.html

Shaw, R. (2014, November 1). The cat's-whisker detector. Retrieved December 3, 2015, from http://rileyjshaw.com/blog/the-cat's-whisker-detector/

Sze, S. (2015, October 1). Semiconductor device | electronics. Retrieved December 3, 2015, from http://www.britannica.com/technology/semiconductor-device

Sze, S. (1981). Physics of semiconductor devices (2nd ed.). New York: Wiley.

"Timeline." Timeline | The Silicon Engine | Computer History Museum. The Silicon Engine, n.d. Web. 27 Nov. 2016.

[[Category:Simple Circuits]]

File:Feol Process.png

2018-11-26T04:43:05Z

Jbuehler3: Steps to create semiconductor device

Steps to create semiconductor device

File:Feol.png

2018-11-26T04:39:20Z

Jbuehler3:

Semiconductor Devices

2018-11-26T04:38:50Z

Jbuehler3:

Last Edited by Joey Buehler (Fall 2018)

Allison Youngsman 12/2/15

'''Claimed by Michael Eden (Fall 2016)'''

'''edited by Eric Lee (Fall 2016)'''

===Semiconductor Devices===

Semiconductor devices are electronic components with the electronic properties of semiconductors. Silicon, germanium, gallium arsenide, organic semiconductors are among the most common semiconductors used in these devices. Semiconductors are materials that are neither good conductors or good insulators. Due to low cost, reliability, and compactness, semiconductors are used for a wide range of applications. They also have a wide range of current and voltage handling capabilities, contributing to their suitability for a number of operations. They are commonly found in power devices, optical sensors, and light emitters. Perhaps more importantly, they are readily integrated into microelectronic uses as key elements for the majority of electronic systems, including communications, consumer, data-processing, and industrial-control equipment.

[[File:Intelthing.jpg|frame|border|right|A raw board with many transistors in it!]]
[[File:transistor.png|frame|none|left|An fully built integrated circuit.]]

==The Main Idea==

Semiconductors work by using the electric properties of the p-n junction that makes up a diode. The junction is formed through a process called doping. Doping involves turning silicon into a conductor by changing the behavior of its electrons. In n-type doping, a phosphorus/arsenic impurity is introduced so that the valence will have free electrons to allow a electric current to flow. Since extra electrons are negative in charge, this type of doping is called n-type doping referred to by "n" in the p-n junction. In the p-type doping, a boron/gallium impurity is introduced to the silicon lattice so the valence will have an empty electron orbital. Because the empty area implies the absence of an electron and thus creates a positive charge, "p" was assigned as the name of the doping type.

[[File:n-type.gif|frame|border|right|N-Type Material]]

[[File:p-type.png|frame|none|left|P-Type Material]]

The two most useful forms of semiconductor devices are diodes and transistors. Diodes are the simplest semiconductor device, which conducts current easily in one direction but conducts almost no current in the other direction. These are made by joining two pieces of semiconducting material,a junction called a "p-n" junction. One of the pieces contains a small amount of boron and the other contains a small amount of phosphorus. Transistors are constructed through two semiconducting junctions, or "p-n" junctions. These are the most common elements in digital circuits. The conductivity of these semiconductors can be controlled by introduction of an electric or magnetic field, by exposure to light or heat, or by mechanical deformation of a doped monocrystalline grid. Due to this, semiconductors are extremely useful and can be altered to fit specific purposes.

===A Mathematical Model===

Semiconductors operate based on the concept of thermal energy exciting electrons and causing them to jump to the next higher (unoccupied) energy band.
These electrons can pick up energy (and drift speed) from an applied electric field. The filled energy band is called the “valence” band, and the nearly unoccupied higher energy band is called the “conduction” band. The number of electrons excited into the conduction band is proportional to a value called the Boltzmann constant, equivalent to the value:
<math>
e^{-E_{\text{gap}} / k_B T}
</math>.
Therefore, high conductivity (corrosponding to a favorable Boltzmann factor) can be calculated according to
<math>
T = 2 \pi \sqrt{\frac{m}{k}}
</math>,
where <math>m</math> is the mass of the object in kilograms, <math>k</math> is the spring constant, and <math>T</math> is the period of oscillation in seconds. In addition, the total conventional current in a semiconductor can be calculated, according to the equation
<math>
I = e n_n A u_n E + e n_p A u_p E
</math>.

===A Conceptual Model===
The following diagram demonstrates how electron excitement in semiconductors works. Semiconductors are materials with small band gaps between the valence band and conduction bands. As you can see, a small amount of thermal energy is needed to promote an electron to the conduction band in a semiconductor.

[[File:conceptual.png|frame|none|left|A Conceptual Model of the Semiconductor]]

==History==
'''1874'''
Ferdinand Braun discovers that current flows freely in only one direction when a metal point and a galena crystal are put together.

'''1901'''
Jagadis Bose takes ownership of the discovery of the semiconductor crystal for detecting radio waves.

'''1940'''
Russell Ohl discovers the p-n junction.

'''1940s'''
Semiconductors were used only as two-terminal devices, such as rectifiers and photodiodes. They were most commonly used as detectors in radios, through devices called "cat's whiskers". During the era of WWII, researchers worked with semiconductors and cat's whiskers to make more effective diodes.

'''1947'''
William Shockley and John Bardeen worked together to create a triode-like semiconductor: the first transistor. They realized that if there were some way to control the flow of the electrons from the emitter to the collector of this newly discovered diode, an amplifier could be built.The first transistor was officially created on the 23rd of December, 1947.

'''1956'''
John Bardeen, William Shockley, and another researcher named Walter Houser Brattain were credited for the invention and awarded a Nobel Prize for physics in 1956 for their work. After this, the utilization of semiconductors soon advanced to even more complicated applications.

'''1960s'''
In the late 1960s, transistors moved from being germanium based to silicon based. Gordon K Teal was most responsible for this advancement, and his company, Texas Instruments, profited greatly. Portable radios are just one popular invention that benefited from silicon based semiconductors. Now, silicon based semiconductors constitute more than 95 percent of all semiconductor hardware sold worldwide.

'''1970s'''
Silicon technology is modernized and the race to fit all semiconductor processor technology into one chip is most active.

[[File:transistorwork.png|frame|none|none|John Bardeen, William Shockley, and Walter Houser Brattain, winners of the Nobel Prize for their invention of the transistor, are pictured above.]]

===Connectedness===

Semiconductors are crucial to modern technology, and are used for memory storage as well as so many other technological innovations. This technology is used every day by millions of people for thousands of different applications. Most people in the world have used semiconductors in one way or another, even if they weren't aware of it. It is specifically connected to the major of Biomedical Engineering through memory storage and the complex computer programs used every day to conduct business and create simulations for the furthering of biomedical research. All industrial applications of semiconductors are very applicable, from amplifiers to transistors to silicon disks. Without semiconductors, much of the technology that the general population relies on today would not be possible.

Semiconductors are used in essentially every part of this technological and electronically-dependent world we live in today. They have both conductor and insulator properties and includes all of the metal we see in wires. Computers, phones, and other electronic devices all use semiconductors to fulfill their functions such as communication and efficiency. The most important aspect of semiconductors is utilization, which is shown through the use of switches. Inside electronic devices, the switches exist in extremely large numbers, which is why electronic devices process information in an incredible speed with surprising efficiency.

==Types of Semiconductors==

===Diodes===

[[File:Diode_current_wiki.png|314px|thumb|right|top|IV Characteristic of a Diode]]

Diodes are really great! In a simple sense, they can give you a "point of no return" in your circuit (but they can actually do much more than that).
Three interesting things should be observed from the IV characteristic shown to the right:

# For small positive voltages and above, the diode does not limit the current (the line is almost vertical)!
# For small to larger negative voltages, the diode resists current (the line is almost flat).
# For a large negative voltage (the breakdown voltage) the diode gives up (no one is perfect).

We can formally define this line with the Shockley Diode Equation, which formalizes this observation:

<math display="block">
I = I_S \left( e^{\frac{V_D}{n V_T}} - 1 \right)
</math> where

<math>I</math> is the diode current,

<math>I_S</math> is the reverse bias saturation current (or scale current),

<math>V_D</math> is the voltage across the diode,

<math>V_T</math> is the thermal voltage, and

<math>n</math> is the ideality factor, (1 if the diode is ideal, greater than 1 if it is imperfect).

A great practical use for diodes is a rectifier:

[[File:Gratz.rectifier.en.svg|frame|border|center|Diodes groups the positive and negative signals together]]

This makes sure that when a positive voltage appears on either line, it is redirected to a single positive line, and the same for the negatives.
BAM! AC to DC, that's pretty easy, you can charge your phone with that.
In reality a capacitor is added in parallel with the load to try to smooth out the ripples.
A voltage regulator after the rectifying step is also a popular choice, depending on the needs of the application.

Another super useful application is that of a back up power supply: simply connect two supplies in parallel with the positive terminals buffered with diodes. The higher of the two voltages is always used and the transition between supplies is seamless.

===Zener Diodes===

Some diodes (Zener) are made to have small breakdown voltages.
Since during breakdown the IV curve is almost vertical (it's really an exponential), the current is independent (almost) from voltage.
You can then wire up a Zener diode in reverse to a point in the circuit, and it will accept as much current as it needs to to reach that
breakdown voltage. Because of this a great practical use for Zener diodes is a voltage regulator since the voltage is set when the diode is
manufactured and does not change greatly with a varying power supply.

===Bipolar Junction Transistors===

[[Image:BJT NPN symbol (case).svg|75px|thumb|NPN BJT]]
[[Image:BJT PNP symbol (case).svg|75px|thumb|PNP BJT]]

Shortly after the invention of the first transistor (which was OK), the BJT landed, which was the first transistor to be prolific in the field.
It was made using two alternating NP junctions as shown below:

[[File:NPN BJT (Planar) Cross-section.svg|frame|border|center|NPN BJT (Planar) Cross-section]]

Really transistors (and by extension all that is needed for a computer to be built) are amplifiers (OK, to build all computers you need an inverting amplifier, but one can be built using the BJT).
If one is used to thinking of them as an electrically-controlled switch, you can simply think of a switch as an amplifier with a gain of <math>\infty</math>.

A simple model of a BJT is a linear current-controlled current source, i.e. the base to emitter (B to E) current <math>I_{BE}</math> is proportional to
the collector to emitter (C to E) current <math>I_{CE}</math>. The proportionality constant <math>\beta</math> can be thought of as the "gain" of the
transistor. This gives a relationship of <math>I_{CE} = \beta I_{BE}</math>.

[[File:Current-Voltage relationship of BJT.png|thumb|right|Current-Voltage relationship of BJT]]

Sadly there is no source of infinite power, so the output to our amplifier tops off when it can't supply any more power.
This can be seen with the graph on the right.
The simple model then only works for the tiny linear part at the start of the graph, even so its not ''that'' linear.
The BJT proved to be power hungry, pretty non-linear and sensitive to the environment (temperature, etc.).
These growing pains lead to a new development, called the MOSFET.

===MOSFETs===

MOSFETs are the coolest, they are less power-hungy and easier to work with when compared to BJTs.
Instead of having a current control, which uses power and gets the control and the output signal coupled together,
a MOSFET's output is controlled by the electric Field (the F in MOSFET) the control signal creates on one of the plates of the MOSFET.
Since the control signal and the output are electrically disconnected (as you would see in a capacitor) there is much less power draw
from this type of transistor.

We can see how linear this thing is with its IV characteristic: <math>I_D= \mu_n C_{ox}\frac{W}{L} \left( (V_{GS}-V_{th})V_{DS}-\frac{V_{DS}^2}{2} \right)</math>

Apart from the control signal <math>V_{DS}</math> and constants, the voltage across the output portion of the MOSFET is linearly related to the current!
This means that the MOSFET behaves like a voltage controlled resistor, and a resistor is something much easier to analyse and work with.

Most circuits with an enormous amount of transistors these days use primarily MOSFETs. BJTs are still useful for temperature and light sensing
applications.

==Industrial Semiconductor Fabrication==

Semiconductors are mass produced in specialized factories called foundries or fabs. The process consists of multiple chemical and photolithographic steps which add layers to a wafer usually made of silicon. The entire process usually takes around 2 months but it can last up to 4.

The semiconductor product is rated by the size of the chip's process gate length, where processes with smaller gate lengths are typically harder to make. There are 10-20 different sized chips being fabricated around the world as of 2018. There is an immense amount of attention and money being dedicated to improving semiconductor fabrication process efficiency.

[[File:feol.png]]

==Examples==

===Simple===
[[File:Cat'swhiskerdetector.jpg]]

A simple application of a semiconductor would be the Cat's Whisker detector for radios, invented in the early 1900s.

===Moderate===
[[File:Opticallsensor.jpg]]

Optical sensors are moderately difficult applications of semiconductors. Optical sensors are electronic detectors that convert light into an electronic signal. They are used in many industrial and consumer applications. An example would include lamps that turn on automatically in response to darkness.

===Difficult===

[[File:Complicated_semiconductor.jpg]]

A very complicated application of a semiconductor is its use in modern cellular phone devices, such as its use here in the iPhone 6.

== See also ==

Related Wiki pages:

-Transformers

-Resistors and conductivity

-Superconductors

-Electric Fields

-Transformers from a physics standpoint

===Further reading===

Chabay, Sherwood. (n.d.). Matter and Interactions (4th ed., Vol. 2). Raleigh, North Carolina: Wiley.

Sze, S. (1981). Physics of semiconductor devices (2nd ed.). New York: Wiley.

===External links===

Wikipedia page about semiconductors:

https://en.wikipedia.org/wiki/Semiconductor_device

Encyclopedia entry about semiconductors, including the history of semiconductors:

http://www.britannica.com/technology/semiconductor-device

Information about Diodes:

https://en.wikipedia.org/wiki/Diode

Information about BJTs:

https://en.wikipedia.org/wiki/Bipolar_junction_transistor

Information about MOSFETs:

https://en.wikipedia.org/wiki/MOSFET

==References==
Brain, Marshall. "How Semiconductors Work." HowStuffWorks. N.p., 25 Apr. 2001. Web. 27 Nov. 2016.

Chabay, Sherwood. (n.d.). Matter and Interactions (4th ed., Vol. 2). Raleigh, North Carolina: Wiley.

Electronics and Semiconductor. (n.d.). Retrieved December 3, 2015, from http://www.plm.automation.siemens.com/en_us/electronics-semiconductor/devices/

Huculak, M. (2014, September 19). IPhone 6 and iPhone 6 Plus get teardown by iFixit • The Windows Site for Enthusiasts - Pureinfotech. Retrieved December 3, 2015, from http://pureinfotech.com/2014/09/19/iphone-6-iphone-6-plus-get-teardown-ifixit/

John Bardeen, William Shockley and Walter Brattain at Bell Labs, 1948. (n.d.). Retrieved December 3, 2015, from https://en.wikipedia.org/wiki/John_Bardeen#/media/File:Bardeen_Shockley_Brattain_1948.JPG

เซ็นเซอร์แสง (Optical Sensor) - Elec-Za.com. (2014, July 28). Retrieved December 3, 2015, from http://www.elec-za.com/เซ็นเซอร์แสง-optical-sensor/

Semiconductor device. (2015, November 30). Retrieved December 3, 2015, from https://en.wikipedia.org/wiki/Semiconductor_device

Shah, A. (2013, May 13). Intel loses ground as world's top semiconductor company, survey says. Retrieved December 3, 2015, from http://www.pcworld.com/article/2038645/intel-loses-ground-as-worlds-top-semiconductor-company-survey-says.html

Shaw, R. (2014, November 1). The cat's-whisker detector. Retrieved December 3, 2015, from http://rileyjshaw.com/blog/the-cat's-whisker-detector/

Sze, S. (2015, October 1). Semiconductor device | electronics. Retrieved December 3, 2015, from http://www.britannica.com/technology/semiconductor-device

Sze, S. (1981). Physics of semiconductor devices (2nd ed.). New York: Wiley.

"Timeline." Timeline | The Silicon Engine | Computer History Museum. The Silicon Engine, n.d. Web. 27 Nov. 2016.

[[Category:Simple Circuits]]

Semiconductor Devices

2018-11-25T22:47:52Z

Jbuehler3:

Last Edited by Joey Buehler (Fall 2018)

Allison Youngsman 12/2/15

'''Claimed by Michael Eden (Fall 2016)'''

'''edited by Eric Lee (Fall 2016)'''

===Semiconductor Devices===

Semiconductor devices are electronic components with the electronic properties of semiconductors. Silicon, germanium, gallium arsenide, organic semiconductors are among the most common semiconductors used in these devices. These "semiconductors" are materials that are neither good conductors or good insulators. Due to low cost, reliability, and compactness, semiconductors are used for a wide range of applications. They also have a wide range of current and voltage handling capabilities, contributing to their suitability for a number of operations. They are commonly found in power devices, optical sensors, and light emitters. Perhaps more importantly, they are readily integrated into microelectronic uses as key elements for the majority of electronic systems, including communications, consumer, data-processing, and industrial-control equipment.

[[File:Intelthing.jpg|frame|border|right|A raw board with many transistors in it!]]
[[File:transistor.png|frame|none|left|An fully built integrated circuit.]]

==The Main Idea==

In the p-n junction that makes up a diode, the junction is formed through a process called doping. Doping involves turning silicon into a conductor by changing the behavior of it. In n-type doping, a phosphorus/arsenic impurity is created so that the resulting free electrons allow a electric current to flow through the silicon. Since electrons are negative in charge, this type of doping is called n-type doping and consists of the "n" in the p-n junction. In the p-type doping, a boron/gallium is added to the silicon lattice and when it happens, an empty area from an unbonded silicon electron forms. Because the empty area implies the absence of an electron and thus creates a positive charge, "p" was assigned as the name of the doping type.

[[File:n-type.gif|frame|border|right|N-Type Material]]

[[File:p-type.png|frame|none|left|P-Type Material]]

The two most useful forms of semiconductor devices are diodes and transistors. Diodes are the simplest semiconductor device, which conducts current easily in one direction but conducts almost no current in the other direction. These are made by joining two pieces of semiconducting material,a junction called a "p-n" junction. One of the pieces contains a small amount of boron and the other contains a small amount of phosphorus. Transistors are constructed through two semiconducting junctions, or "p-n" junctions. These are the most common elements in digital circuits. The conductivity of these semiconductors can be controlled by introduction of an electric or magnetic field, by exposure to light or heat, or by mechanical deformation of a doped monocrystalline grid. Due to this, semiconductors are extremely useful and can be altered to fit specific purposes.

===A Mathematical Model===

Semiconductors operate based on the concept of thermal energy exciting electrons and causing them to jump to the next higher (unoccupied) energy band.
These electrons can pick up energy (and drift speed) from an applied electric field. The filled energy band is called the “valence” band, and the nearly unoccupied higher energy band is called the “conduction” band. The number of electrons excited into the conduction band is proportional to a value called the Boltzmann constant, equivalent to the value:
<math>
e^{-E_{\text{gap}} / k_B T}
</math>.
Therefore, high conductivity (corrosponding to a favorable Boltzmann factor) can be calculated according to
<math>
T = 2 \pi \sqrt{\frac{m}{k}}
</math>,
where <math>m</math> is the mass of the object in kilograms, <math>k</math> is the spring constant, and <math>T</math> is the period of oscillation in seconds. In addition, the total conventional current in a semiconductor can be calculated, according to the equation
<math>
I = e n_n A u_n E + e n_p A u_p E
</math>.

===A Conceptual Model===
The following diagram demonstrates how electron excitement in semiconductors works. Semiconductors are materials with small band gaps between the valence band and conduction bands. As you can see, a small amount of thermal energy is needed to promote an electron to the conduction band in a semiconductor.

[[File:conceptual.png|frame|none|left|A Conceptual Model of the Semiconductor]]

==History==
'''1874'''
Ferdinand Braun discovers that current flows freely in only one direction when a metal point and a galena crystal are put together.

'''1901'''
Jagadis Bose takes ownership of the discovery of the semiconductor crystal for detecting radio waves.

'''1940'''
Russell Ohl discovers the p-n junction.

'''1941-late 1960s'''
The studying of semiconductor materials first began around the beginning of the 19th century. Prior to 1947, semiconductors were used only as two-terminal devices, such as rectifiers and photodiodes. They were most commonly used as detectors in radios, through devices called "cat's whiskers". During the era of WWII, researchers worked with semiconductors and cat's whiskers to make more effective diodes. After the war, two researchers named William Shockley and John Bardeen worked together to create a triode-like semiconductor: the first transistor. They realized that if there were some way to control the flow of the electrons from the emitter to the collector of this newly discovered diode, an amplifier could be built.The first transistor was officially created on the 23rd of December, 1947. John Bardeen, William Shockley, and another researcher named Walter Houser Brattain were credited for the invention and awarded a Nobel Prize for physics in 1956 for their work. After this, the utilization of semiconductors soon advanced to even more complicated applications. In the late 1960s, transistors moved from being germanium based to silicon based. Gordon K Teal was most responsible for this advancement, and his company, Texas Instruments, profited greatly. Portable radios are just one popular invention that benefited from silicon based semiconductors. Now, silicon based semiconductors constitute more than 95 percent of all semiconductor hardware sold worldwide.

'''1970s'''
Silicon technology is modernized and the race to fit all semiconductor processor technology into one chip is most active.

[[File:transistorwork.png|frame|none|none|John Bardeen, William Shockley, and Walter Houser Brattain, winners of the Nobel Prize for their invention of the transistor, are pictured above.]]

===Connectedness===

Semiconductors are crucial to modern technology, and are used for memory storage as well as so many other technological innovations. This technology is used every day by millions of people for thousands of different applications. Most people in the world have used semiconductors in one way or another, even if they weren't aware of it. It is specifically connected to the major of Biomedical Engineering through memory storage and the complex computer programs used every day to conduct business and create simulations for the furthering of biomedical research. All industrial applications of semiconductors are very applicable, from amplifiers to transistors to silicon disks. Without semiconductors, much of the technology that the general population relies on today would not be possible.

Semiconductors are used in essentially every part of this technological and electronically-dependent world we live in today. They have both conductor and insulator properties and includes all of the metal we see in wires. Computers, phones, and other electronic devices all use semiconductors to fulfill their functions such as communication and efficiency. The most important aspect of semiconductors is utilization, which is shown through the use of switches. Inside electronic devices, the switches exist in extremely large numbers, which is why electronic devices process information in an incredible speed with surprising efficiency.

==Types of Semiconductors==

===Diodes===

[[File:Diode_current_wiki.png|314px|thumb|right|top|IV Characteristic of a Diode]]

Diodes are really great! In a simple sense, they can give you a "point of no return" in your circuit (but they can actually do much more than that).
Three interesting things should be observed from the IV characteristic shown to the right:

# For small positive voltages and above, the diode does not limit the current (the line is almost vertical)!
# For small to larger negative voltages, the diode resists current (the line is almost flat).
# For a large negative voltage (the breakdown voltage) the diode gives up (no one is perfect).

We can formally define this line with the Shockley Diode Equation, which formalizes this observation:

<math display="block">
I = I_S \left( e^{\frac{V_D}{n V_T}} - 1 \right)
</math> where

<math>I</math> is the diode current,

<math>I_S</math> is the reverse bias saturation current (or scale current),

<math>V_D</math> is the voltage across the diode,

<math>V_T</math> is the thermal voltage, and

<math>n</math> is the ideality factor, (1 if the diode is ideal, greater than 1 if it is imperfect).

A great practical use for diodes is a rectifier:

[[File:Gratz.rectifier.en.svg|frame|border|center|Diodes groups the positive and negative signals together]]

This makes sure that when a positive voltage appears on either line, it is redirected to a single positive line, and the same for the negatives.
BAM! AC to DC, that's pretty easy, you can charge your phone with that.
In reality a capacitor is added in parallel with the load to try to smooth out the ripples.
A voltage regulator after the rectifying step is also a popular choice, depending on the needs of the application.

Another super useful application is that of a back up power supply: simply connect two supplies in parallel with the positive terminals buffered with diodes. The higher of the two voltages is always used and the transition between supplies is seamless.

===Zener Diodes===

Some diodes (Zener) are made to have small breakdown voltages.
Since during breakdown the IV curve is almost vertical (it's really an exponential), the current is independent (almost) from voltage.
You can then wire up a Zener diode in reverse to a point in the circuit, and it will accept as much current as it needs to to reach that
breakdown voltage. Because of this a great practical use for Zener diodes is a voltage regulator since the voltage is set when the diode is
manufactured and does not change greatly with a varying power supply.

===Bipolar Junction Transistors===

[[Image:BJT NPN symbol (case).svg|75px|thumb|NPN BJT]]
[[Image:BJT PNP symbol (case).svg|75px|thumb|PNP BJT]]

Shortly after the invention of the first transistor (which was OK), the BJT landed, which was the first transistor to be prolific in the field.
It was made using two alternating NP junctions as shown below:

[[File:NPN BJT (Planar) Cross-section.svg|frame|border|center|NPN BJT (Planar) Cross-section]]

Really transistors (and by extension all that is needed for a computer to be built) are amplifiers (OK, to build all computers you need an inverting amplifier, but one can be built using the BJT).
If one is used to thinking of them as an electrically-controlled switch, you can simply think of a switch as an amplifier with a gain of <math>\infty</math>.

A simple model of a BJT is a linear current-controlled current source, i.e. the base to emitter (B to E) current <math>I_{BE}</math> is proportional to
the collector to emitter (C to E) current <math>I_{CE}</math>. The proportionality constant <math>\beta</math> can be thought of as the "gain" of the
transistor. This gives a relationship of <math>I_{CE} = \beta I_{BE}</math>.

[[File:Current-Voltage relationship of BJT.png|thumb|right|Current-Voltage relationship of BJT]]

Sadly there is no source of infinite power, so the output to our amplifier tops off when it can't supply any more power.
This can be seen with the graph on the right.
The simple model then only works for the tiny linear part at the start of the graph, even so its not ''that'' linear.
The BJT proved to be power hungry, pretty non-linear and sensitive to the environment (temperature, etc.).
These growing pains lead to a new development, called the MOSFET.

===MOSFETs===

MOSFETs are the coolest, they are less power-hungy and easier to work with when compared to BJTs.
Instead of having a current control, which uses power and gets the control and the output signal coupled together,
a MOSFET's output is controlled by the electric Field (the F in MOSFET) the control signal creates on one of the plates of the MOSFET.
Since the control signal and the output are electrically disconnected (as you would see in a capacitor) there is much less power draw
from this type of transistor.

We can see how linear this thing is with its IV characteristic: <math>I_D= \mu_n C_{ox}\frac{W}{L} \left( (V_{GS}-V_{th})V_{DS}-\frac{V_{DS}^2}{2} \right)</math>

Apart from the control signal <math>V_{DS}</math> and constants, the voltage across the output portion of the MOSFET is linearly related to the current!
This means that the MOSFET behaves like a voltage controlled resistor, and a resistor is something much easier to analyse and work with.

Most circuits with an enormous amount of transistors these days use primarily MOSFETs. BJTs are still useful for temperature and light sensing
applications.

==Examples==

===Simple===
[[File:Cat'swhiskerdetector.jpg]]

A simple application of a semiconductor would be the Cat's Whisker detector for radios, invented in the early 1900s.

===Moderate===
[[File:Opticallsensor.jpg]]

Optical sensors are moderately difficult applications of semiconductors. Optical sensors are electronic detectors that convert light into an electronic signal. They are used in many industrial and consumer applications. An example would include lamps that turn on automatically in response to darkness.

===Difficult===

[[File:Complicated_semiconductor.jpg]]

A very complicated application of a semiconductor is its use in modern cellular phone devices, such as its use here in the iPhone 6.

== See also ==

Related Wiki pages:

-Transformers

-Resistors and conductivity

-Superconductors

-Electric Fields

-Transformers from a physics standpoint

===Further reading===

Chabay, Sherwood. (n.d.). Matter and Interactions (4th ed., Vol. 2). Raleigh, North Carolina: Wiley.

Sze, S. (1981). Physics of semiconductor devices (2nd ed.). New York: Wiley.

===External links===

Wikipedia page about semiconductors:

https://en.wikipedia.org/wiki/Semiconductor_device

Encyclopedia entry about semiconductors, including the history of semiconductors:

http://www.britannica.com/technology/semiconductor-device

Information about Diodes:

https://en.wikipedia.org/wiki/Diode

Information about BJTs:

https://en.wikipedia.org/wiki/Bipolar_junction_transistor

Information about MOSFETs:

https://en.wikipedia.org/wiki/MOSFET

==References==
Brain, Marshall. "How Semiconductors Work." HowStuffWorks. N.p., 25 Apr. 2001. Web. 27 Nov. 2016.

Chabay, Sherwood. (n.d.). Matter and Interactions (4th ed., Vol. 2). Raleigh, North Carolina: Wiley.

Electronics and Semiconductor. (n.d.). Retrieved December 3, 2015, from http://www.plm.automation.siemens.com/en_us/electronics-semiconductor/devices/

Huculak, M. (2014, September 19). IPhone 6 and iPhone 6 Plus get teardown by iFixit • The Windows Site for Enthusiasts - Pureinfotech. Retrieved December 3, 2015, from http://pureinfotech.com/2014/09/19/iphone-6-iphone-6-plus-get-teardown-ifixit/

John Bardeen, William Shockley and Walter Brattain at Bell Labs, 1948. (n.d.). Retrieved December 3, 2015, from https://en.wikipedia.org/wiki/John_Bardeen#/media/File:Bardeen_Shockley_Brattain_1948.JPG

เซ็นเซอร์แสง (Optical Sensor) - Elec-Za.com. (2014, July 28). Retrieved December 3, 2015, from http://www.elec-za.com/เซ็นเซอร์แสง-optical-sensor/

Semiconductor device. (2015, November 30). Retrieved December 3, 2015, from https://en.wikipedia.org/wiki/Semiconductor_device

Shah, A. (2013, May 13). Intel loses ground as world's top semiconductor company, survey says. Retrieved December 3, 2015, from http://www.pcworld.com/article/2038645/intel-loses-ground-as-worlds-top-semiconductor-company-survey-says.html

Shaw, R. (2014, November 1). The cat's-whisker detector. Retrieved December 3, 2015, from http://rileyjshaw.com/blog/the-cat's-whisker-detector/

Sze, S. (2015, October 1). Semiconductor device | electronics. Retrieved December 3, 2015, from http://www.britannica.com/technology/semiconductor-device

Sze, S. (1981). Physics of semiconductor devices (2nd ed.). New York: Wiley.

"Timeline." Timeline | The Silicon Engine | Computer History Museum. The Silicon Engine, n.d. Web. 27 Nov. 2016.

[[Category:Simple Circuits]]

Paul Dirac

2015-12-06T03:04:57Z

Jbuehler3:

jbuehler3

Born in August 1902, Paul Adrien Maurice Dirac was an influential theoretical physicist. Throughout his life he worked on quantum mechanics and even invented a new subfield of quantum electrodynamics. He won a Nobel Prize in 1933. He had a family with a wife, two of his own children, and two adopted children. He died in 1984.

[[File:330px_Dirac_4.jpg]]

==The Main Idea==

Dirac's work in theoretical physics was monumental in the creation and modernization of quantum physics. He derived equations that are critical in in applying the relativistic model of space time into quantum mechanics. While working alongside many famous and influential physicists of his time including Einstien, Shrodinger, and Feynman, he helped to tie many other equations and natural phenomenon together into mathmatics. He was once quoted saying that the laws of nature should be described by beautiful equations.

===A Mathematical Model===

The Dirac equation is a combination many discoveries and innovations that were occurring at the beginning of the 20th century. The equation helps to relate the wave function of an electron to the curvature of spacetime. In order to do this, both the Planck constant(h) and the Shrodinger equation are referenced.

[[File:diracequation.png]]

The second form of the equation helps to make the math fit with Pauli matrices. This added dimension allows the algebra to work for a pseudo orthoganal 4D space, which is necessary to consider the application of momentum on a curved spacetime.

[[File:2.png]]

In order to continue simplification, the equation becomes

[[File:3.png]]

which replaced the Planck constant and the speed of light with 1 which is often called natural units. This form of the equation still creates the same model of space.

These equations were monumental in the discovery of antimatter and the positron. They are unique in the fact that they reconcile general relativity with quantum mechanics.

==History==

Dirac was from Bristol, England and he was born on 8 August, 1902. He was a Swiss national until he was naturalized. He attended the University of Bristol and the University of Cambridge, both on scholarship. He did research in the field of quantum electrodynamics and quantum physics for the years to come. Some said that he was obsessed and weird. In 1933 he shared a Nobel Prize with Erwin Schrodinger for the development of new models and equations for atoms. When he was 35 he married Margit Wigner, and adopted both of her children. The couple later went on to have two more children of their own. He continued to write papers, do research, and teach for the rest of his life. He moved to America to be closer to his daughter. He died at the age of 82 in Tallahassee, Florida.

==Connectedness==
Although we did not go into much depth on any kind of quantum physics, these equations are still fundamental to understanding the current relativistic and quantum models of the universe. Physics one concentrates much more on the macro side of molecules and systems.

These models do not really have any practical industrial use because they are mainly theoretical. While Dirac was trying to explain how the universe worked, he was not as much focused on how to apply that to industry.

Chemical and Biomolecular Engineering does not focus on the deep math that makes up much of quantum physics because it is not very applicable to the job field.

== See also ==

http://www.physicsbook.gatech.edu/Erwin_Schrodinger
http://www.physicsbook.gatech.edu/Albert_Einstein
http://www.physicsbook.gatech.edu/Max_Planck
http://www.physicsbook.gatech.edu/Electromagnetic_Propagation

===Further reading===

http://www-history.mcs.st-and.ac.uk/Biographies/Dirac.html
http://www.nobelprize.org/nobel_prizes/physics/laureates/1933/dirac-bio.html
https://en.wikipedia.org/wiki/Paul_Dirac
https://en.wikipedia.org/wiki/Dirac_equation

==References==

http://www.nyu.edu/classes/tuckerman/quant.mech/lectures/lecture_6/node5.html
http://www.britannica.com/biography/Paul-Dirac
http://www.famousscientists.org/paul-dirac/

[[Category:Notable Figures]]

Paul Dirac

2015-12-06T02:58:24Z

2015-12-05T22:21:35Z

Jbuehler3: Created page with "jbuehler3 Short Description of Topic ==The Main Idea== State, in your own words, the main idea for this topic ===A Mathematical Model=== What are the mathematical equati..."

jbuehler3

Short Description of Topic

==The Main Idea==

State, in your own words, the main idea for this topic

===A Mathematical Model===

What are the mathematical equations that allow us to model this topic. For example <math>{\frac{d\vec{p}}{dt}}_{system} = \vec{F}_{net}</math> where '''p''' is the momentum of the system and '''F''' is the net force from the surroundings.

===A Computational Model===

How do we visualize or predict using this topic. Consider embedding some vpython code here [https://trinket.io/glowscript/31d0f9ad9e Teach hands-on with GlowScript]

==Examples==

Be sure to show all steps in your solution and include diagrams whenever possible

===Simple===
===Middling===
===Difficult===

==Connectedness==
#How is this topic connected to something that you are interested in?
#How is it connected to your major?
#Is there an interesting industrial application?

==History==

Put this idea in historical context. Give the reader the Who, What, When, Where, and Why.

== See also ==

Are there related topics or categories in this wiki resource for the curious reader to explore? How does this topic fit into that context?

===Further reading===

Books, Articles or other print media on this topic

===External links===
[http://www.scientificamerican.com/article/bring-science-home-reaction-time/]

==References==

This section contains the the references you used while writing this page

[[Category:Which Category did you place this in?]]

Main Page

2015-12-05T22:20:05Z

Jbuehler3:

__NOTOC__
Welcome to the Georgia Tech Wiki for Intro Physics. This resources was created so that students can contribute and curate content to help those with limited or no access to a textbook. When reading this website, please correct any errors you may come across. If you read something that isn't clear, please consider revising it!

Looking to make a contribution?
#Pick a specific topic from intro physics
#Add that topic, as a link to a new page, under the appropriate category listed below by editing this page.
#Copy and paste the default [[Template]] into your new page and start editing.

Please remember that this is not a textbook and you are not limited to expressing your ideas with only text and equations. Whenever possible embed: pictures, videos, diagrams, simulations, computational models (e.g. Glowscript), and whatever content you think makes learning physics easier for other students.

== Source Material ==
All of the content added to this resource must be in the public domain or similar free resource. If you are unsure about a source, contact the original author for permission. That said, there is a surprisingly large amount of introductory physics content scattered across the web. Here is an incomplete list of intro physics resources (please update as needed).
* A physics resource written by experts for an expert audience [https://en.wikipedia.org/wiki/Portal:Physics Physics Portal]
* A wiki book on modern physics [https://en.wikibooks.org/wiki/Modern_Physics Modern Physics Wiki]
* The MIT open courseware for intro physics [http://ocw.mit.edu/resources/res-8-002-a-wikitextbook-for-introductory-mechanics-fall-2009/index.htm MITOCW Wiki]
* An online concept map of intro physics [http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html HyperPhysics]
* Interactive physics simulations [https://phet.colorado.edu/en/simulations/category/physics PhET]
* OpenStax algebra based intro physics textbook [https://openstaxcollege.org/textbooks/college-physics College Physics]
* The Open Source Physics project is a collection of online physics resources [http://www.opensourcephysics.org/ OSP]
* A resource guide compiled by the [http://www.aapt.org/ AAPT] for educators [http://www.compadre.org/ ComPADRE]

== Organizing Categories ==
These are the broad, overarching categories, that we cover in two semester of introductory physics. You can add subcategories or make a new category as needed. A single topic should direct readers to a page in one of these catagories.

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===Interactions===
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*[[Kinds of Matter]]
**[[Ball and Spring Model of Matter]]
*[[Detecting Interactions]]
*[[Escape Velocity]]
*[[Fundamental Interactions]]
*[[Determinism]]
*[[System & Surroundings]]
*[[Free Body Diagram]]
*[[Newton's First Law of Motion]]
*[[Newton's Second Law of Motion]]
*[[Newton's Third Law of Motion]]
*[[Gravitational Force]]
*[[Electric Force]]
*[[Conservation of Energy]]
*[[Conservation of Charge]]
*[[Terminal Speed]]
*[[Simple Harmonic Motion]]
*[[Speed and Velocity]]
*[[Electric Polarization]]
*[[Perpetual Freefall (Orbit)]]
*[[2-Dimensional Motion]]
*[[Center of Mass]]
*[[Reaction Time]]
*[[Time Dilation]]
*[[Pauli exclusion principle]]
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===Modeling with VPython===
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*[[VPython]]
*[[VPython basics]]
*[[VPython Common Errors and Troubleshooting]]
*[[VPython Functions]]
*[[VPython Lists]]
*[[VPython Multithreading]]
*[[VPython Animation]]
*[[VPython 3D Objects]]
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===Theory===
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*[[Einstein's Theory of Special Relativity]]
*[[Einstein's Theory of General Relativity]]
*[[Quantum Theory]]
*[[Maxwell's Electromagnetic Theory]]
*[[Atomic Theory]]
*[[String Theory]]
*[[Elementary Particles and Particle Physics Theory]]
*[[Law of Gravitation]]
*[[Newton's Laws]]
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===Notable Scientists===
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*[[Alexei Alexeyevich Abrikosov]]
*[[Christian Doppler]]
*[[Albert Einstein]]
*[[Ernest Rutherford]]
*[[Joseph Henry]]
*[[Michael Faraday]]
*[[J.J. Thomson]]
*[[James Maxwell]]
*[[Robert Hooke]]
*[[Carl Friedrich Gauss]]
*[[Nikola Tesla]]
*[[Andre Marie Ampere]]
*[[Sir Isaac Newton]]
*[[J. Robert Oppenheimer]]
*[[Oliver Heaviside]]
*[[Rosalind Franklin]]
*[[Enrico Fermi]]
*[[Robert J. Van de Graaff]]
*[[Charles de Coulomb]]
*[[Hans Christian Ørsted]]
*[[Philo Farnsworth]]
*[[Niels Bohr]]
*[[Georg Ohm]]
*[[Galileo Galilei]]
*[[Gustav Kirchhoff]]
*[[Max Planck]]
*[[Heinrich Hertz]]
*[[Edwin Hall]]
*[[James Watt]]
*[[Count Alessandro Volta]]
*[[Josiah Willard Gibbs]]
*[[Richard Phillips Feynman]]
*[[Sir David Brewster]]
*[[Daniel Bernoulli]]
*[[William Thomson]]
*[[Leonhard Euler]]
*[[Robert Fox Bacher]]
*[[Stephen Hawking]]
*[[Amedeo Avogadro]]
*[[Wilhelm Conrad Roentgen]]
*[[Pierre Laplace]]
*[[Thomas Edison]]
*[[Hendrik Lorentz]]
*[[Jean-Baptiste Biot]]
*[[Lise Meitner]]
*[[Lisa Randall]]
*[[Felix Savart]]
*[[Heinrich Lenz]]
*[[Max Born]]
*[[Archimedes]]
*[[Jean Baptiste Biot]]
*[[Carl Sagan]]
*[[Eugene Wigner]]
*[[Marie Curie]]
*[[Pierre Curie]]
*[[Werner Heisenberg]]
*[[Johannes Diderik van der Waals]]
*[[Louis de Broglie]]
*[[Aristotle]]
*[[Émilie du Châtelet]]
*[[Blaise Pascal]]
*[[Siméon Denis Poisson]]
*[[Benjamin Franklin]]
*[[James Chadwick]]
*[[Henry Cavendish]]
*[[Thomas Young]]
*[[James Prescott Joule]]
*[[John Bardeen]]
*[[Leo Baekeland]]
*[[Alhazen]]
*[[Willebrord Snell]]
*[[Fritz Walther Meissner]]
*[[Johannes Kepler]]
*[[Johann Wilhelm Ritter]]
*[[Philipp Lenard]]
*[[Robert A. Millikan]]
*[[Joseph Louis Gay-Lussac]]
*[[Guglielmo Marconi]]
*[[William Lawrence Bragg]]
*[[Robert Goddard]]
*[[Léon Foucault]]
*[[Henri Poincaré]]
*[[Steven Weinberg]]
*[[Arthur Compton]]
*[[Pythagoras of Samos]]
*[[Subrahmanyan Chandrasekhar]]
*[[Wilhelm Eduard Weber]]
*[[Edmond Becquerel]]
*[[Joseph Rotblat]]
*[[Carl David Anderson]]
*[[Hermann von Helmholtz]]
*[[Nicolas Leonard Sadi Carnot]]
*[[Wallace Carothers]]
*[[David J. Wineland]]
*[[Rudolf Clausius]]
*[[Edward L. Norton]]
*[[Shuji Nakamura]]
*[[Pierre Laplace Pt. 2]]
*[[William B. Shockley]]
*[[Osborne Reynolds]]
*[[Alexander Graham Bell]]
*[[Hans Bethe]]
*[[Erwin Schrodinger]]
*[[Wolfgang Pauli]]
*[[Paul Dirac]]

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</div>

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===Properties of Matter===
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*[[Mass]]
*[[Velocity]]
*[[Relative Velocity]]
*[[Density]]
*[[Charge]]
*[[Spin]]
*[[SI Units]]
*[[Heat Capacity]]
*[[Specific Heat]]
*[[Wavelength]]
*[[Conductivity]]
*[[Malleability]]
*[[Weight]]
*[[Boiling Point]]
*[[Melting Point]]
*[[Inertia]]
*[[Non-Newtonian Fluids]]
*[[Ferrofluids]]
*[[Color]]
*[[Temperature]]
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===Contact Interactions===
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* [[Young's Modulus]]
* [[Friction]]
* [[Tension]]
* [[Hooke's Law]]
*[[Centripetal Force and Curving Motion]]
*[[Compression or Normal Force]]
* [[Length and Stiffness of an Interatomic Bond]]
* [[Speed of Sound in Solids]]
* [[Iterative Prediction of Spring-Mass System]]
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===Momentum===
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* [[Vectors]]
* [[Kinematics]]
* [[Conservation of Momentum]]
* [[Predicting Change in multiple dimensions]]
* [[Derivation of the Momentum Principle]]
* [[Momentum Principle]]
* [[Impulse Momentum]]
* [[Curving Motion]]
* [[Projectile Motion]]
* [[Multi-particle Analysis of Momentum]]
* [[Iterative Prediction]]
* [[Analytical Prediction]]
* [[Newton's Laws and Linear Momentum]]
* [[Net Force]]
* [[Center of Mass]]
* [[Momentum at High Speeds]]
* [[Change in Momentum in Time for Curving Motion]]
* [[Momentum with respect to external Forces]]
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===Angular Momentum===
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* [[The Moments of Inertia]]
* [[Moment of Inertia for a cylinder]]
* [[Rotation]]
* [[Torque]]
* [[Systems with Zero Torque]]
* [[Systems with Nonzero Torque]]
* [[Torque vs Work]]
* [[Angular Impulse]]
* [[Right Hand Rule]]
* [[Angular Velocity]]
* [[Predicting the Position of a Rotating System]]
* [[Translational Angular Momentum]]
* [[The Angular Momentum Principle]]
* [[Angular Momentum of Multiparticle Systems]]
* [[Rotational Angular Momentum]]
* [[Total Angular Momentum]]
* [[Gyroscopes]]
* [[Angular Momentum Compared to Linear Momentum]]

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===Energy===
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*[[The Photoelectric Effect]]
*[[Photons]]
*[[The Energy Principle]]
*[[Predicting Change]]
*[[Rest Mass Energy]]
*[[Kinetic Energy]]
*[[Potential Energy]]
**[[Potential Energy for a Magnetic Dipole]]
**[[Potential Energy of a Multiparticle System]]
*[[Work]]
**[[Work Done By A Nonconstant Force]]
*[[Work and Energy for an Extended System]]
*[[Thermal Energy]]
*[[Conservation of Energy]]
*[[Electric Potential]]
*[[Energy Transfer due to a Temperature Difference]]
*[[Gravitational Potential Energy]]
*[[Point Particle Systems]]
*[[Real Systems]]
*[[Spring Potential Energy]]
**[[Ball and Spring Model]]
*[[Internal Energy]]
**[[Potential Energy of a Pair of Neutral Atoms]]
*[[Translational, Rotational and Vibrational Energy]]
*[[Franck-Hertz Experiment]]
*[[Power (Mechanical)]]
*[[Transformation of Energy]]

*[[Energy Graphs]]
**[[Energy graphs and the Bohr model]]
*[[Air Resistance]]
*[[Electronic Energy Levels]]
*[[Second Law of Thermodynamics and Entropy]]
*[[Specific Heat Capacity]]
*[[The Maxwell-Boltzmann Distribution]]
*[[Electronic Energy Levels and Photons]]
*[[Energy Density]]
*[[Bohr Model]]
*[[Quantized energy levels]]
**[[Spontaneous Photon Emission]]
*[[Path Independence of Electric Potential]]
*[[Energy in a Circuit]]
*[[The Photovoltaic Effect]]
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===Collisions===
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[[File:opener.png]]

*[[Collisions]]
Collisions are events that happen very frequently in our day-to-day world. In the realm of Physics, a collision is defined as any sort of process in which before and after a short time interval there is little interaction, but during that short time interval there are large interactions. When looking at collisions, it is first important to understand two very important principles: the Momentum Principle and the Energy Principle. Both principles serve use when talking of collisions because they provide a way in which to analyze these collisions. Collisions themselves can be categorized into 3 main different types: elastic collisions, inelastic collisions, maximally inelastic collisions. All 3 collisions will get touched on in more detail further on.
[[File:pe.png]]

*[[Elastic Collisions]]
A collision is deemed "elastic" when the internal energy of the objects in the system does not change (in other words, change in internal energy equals 0). Because in an elastic collision no kinetic energy is converted over to internal energy, in any elastic collision Kfinal always equals Kinitial.
[[File:Elco.png]]

*[[Inelastic Collisions]]
A collision is said to be "inelastic" when it is not elastic; therefore, an inelastic collision is an interaction in which some change in internal energy occurs between the colliding objects (in other words, change in internal energy does not equal 0). Examples of such changes that occur between colliding objects include, but are not limited to, things like they get hot, or they vibrate/rotate, or they deform. Because some of the kinetic energy is converted to internal energy during an inelastic collision, Kfinal does not equal Kinitial.
There are a few characteristics that one can search for when identifying inelasticity. These indications include things such as:
*Objects stick together after the collision
*An object is in an excited state after the collision
*An object becomes deformed after the collision
*The objects become hotter after the collision
*There exists more vibration or rotation after the collision
[[File:inve.gif]]

*[[Maximally Inelastic Collision]]
Maximally inelastic collisions, also known as "sticking collisions", are the most extreme kinds of inelastic collisions. Just as its secondary name implies, a maximally inelastic collision is one in which the colliding objects stick together creating maximum dissipation. This does not automatically mean that the colliding objects stop dead because the law of conservation of momentum. In a maximally inelastic collision, the remaining kinetic energy is present only because total momentum can't change and must be conserved.
[[File:inel.gif]]

*[[Head-on Collision of Equal Masses]]
The easiest way to understand this phenomenon is to look at it through an example. In this case, we can analyze it through the common game of billiards. Taking the two, equally massed billiard balls as the system, we can neglect the small frictional force exerted on the balls by the billiard table. The Momentum Principle states that in this head-on collision of billiard balls the total final momentum in the x direction must equal the total initial momentum. However, this alone does not give us the knowledge to know how the momentum will be divided up between the two balls. Considering the law of conservation of energy, we can more accurately depict what will happen. This will also allow for one to identify what kind of collision occurs (elastic, inelastic, or maximally inelastic). It is important to know that head-on collisions of equal masses do not have a definite type of collision associated with it.
[[File:momentum-real-life-applications-2895.jpg]] [[File:8ball.gif]]

*[[Head-on Collision of Unequal Masses]]
Just as with head-on collisions of equal masses, it is easy to understand head-on collisions of unequal masses by viewing it through an example. Let's take for example two balls of unequal masses like a ping-pong ball and a bowling ball. For the purpose of this example (so as to allow for no friction and no other significant external forces), let's imagine these objects collide in outer space inside an orbiting spacecraft. If there were to be a collision between the two, what would one expect to happen? One could expect to see the ping-pong ball collide with the bowling ball and bounce straight back with a very small change of speed. What one might not expect as much is that the bowling ball also moves, just very slowly. Again, this can all be explained through the conservation of momentum and the conservation of energy.
[[File:mi3e.jpg]]

*[[Frame of Reference]]
In the world of Physics, a frame of reference is the perspective from which a system is observed. It can be stationary or sometimes it can even be moving at a constant velocity. In some rare cases, the frame of reference moves at an nonconstant velocity and is deemed "noninertial" meaning the basic laws of physics do not apply. Continuing with the trend of examples, pretend you are at a train station observing trains as they pass by. From your stationary frame of reference, you observe that the passenger on the train is moving at the same velocity as the train. However, from a moving frame of reference, say from the eyes of the train conductor, he would view the train passengers as "anchored" to the train.
[[File:train.png]]

*[[Scattering: Collisions in 2D and 3D]]
Experiments that involve scattering are often used to study the structure and behavior of atoms, nuclei, as well as of other small particles. In an experiment like such, a beam of particles collides with other particles. If it is an atomic or nuclear collision, we are unable to observe the curving trajectories inside the tiny region of interaction. Instead, we can only truly observe the trajectories before and after the collision. This is only possible because the particles are at a farther distance apart and have a very weak mutual interaction; this essentially means that the particles are moving almost in a straight line. A good example which demonstrates scattering is the collision between an alpha particle (the nucleus of a helium atom) and the nucleus of a gold atom. One will understand this phenomenon more in depth after first understanding the Rutherford Experiment which will get touched on later.

*[[Rutherford Experiment and Atomic Collisions]]
In England in 1911, a famous experiment was performed by a group of scientists led by Mr. Ernest Rutherford. This experiment, later known as "The Rutherford Experiment", was a tremendous breakthrough for its time because it led to the discovery of the nucleus inside the atom. Rutherford's experiment involved the scattering of a high-speed alpha particle (now known as a helium nuclei - 2 protons and 2 neutrons) as it was shot at a thin gold foil (consisting of a nuclei with 79 protons and 118 neutrons). In the experiment, Rutherford and his team discovered that the velocity of the alpha particles was not high enough to allow the particles to make actual contact with the gold nucleus. Although they never actually made contact, it is still deemed a collision because there exists a sizable force between the alpha particle and the gold nucleus over a very short period of time. In conclusion, we say the alpha particle is "scattered" by its interaction with the nucleus of a gold atom and experiments like such are called "scattering" experiments.
[[File:ruthef.jpg]]

*[[Coefficient of Restitution]]
The coefficient of restitution is a measure of the elasticity in a collision. It is the ratio of the differences in velocities before and after the collision. The coefficient is evaluated by taking the difference in the velocities of the colliding objects after the collision and dividing by the difference in the velocities of the colliding objects before the collision.

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===Fields===
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* [[Electric Field]] of a
** [[Point Charge]]
** [[Electric Dipole]]
** [[Capacitor]]
** [[Charged Rod]]
** [[Charged Ring]]
** [[Charged Disk]]
** [[Charged Spherical Shell]]
** [[Charged Cylinder]]
**[[A Solid Sphere Charged Throughout Its Volume]]
*[[Charge Density]]
*[[Superposition Principle]]
*[[Electric Potential]]
**[[Potential Difference Path Independence]]
**[[Potential Difference in a Uniform Field]]
**[[Potential Difference of point charge in a non-Uniform Field]]
**[[Potential Difference at One Location]]
**[[Sign of Potential Difference]]
**[[Potential Difference in an Insulator]]
**[[Energy Density and Electric Field]]
** [[Systems of Charged Objects]]
*[[Electric Force]]
*[[Polarization]]
**[[Polarization of an Atom]]
**[[Polarization of a conductor]]
*[[Charge Motion in Metals]]
*[[Charge Transfer]]
*[[Magnetic Field]]
**[[Right-Hand Rule]]
**[[Direction of Magnetic Field]]
**[[Magnetic Field of a Long Straight Wire]]
**[[Magnetic Field of a Loop]]
**[[Magnetic Field of a Solenoid]]
**[[Bar Magnet]]
**[[Magnetic Dipole Moment]]
***[[Stern-Gerlach Experiment]]
**[[Magnetic Torque]]
**[[Magnetic Force]]
**[[Earth's Magnetic Field]]
**[[Atomic Structure of Magnets]]
*[[Combining Electric and Magnetic Forces]]
**[[Hall Effect]]
**[[Lorentz Force]]
**[[Biot-Savart Law]]
**[[Biot-Savart Law for Currents]]
**[[Integration Techniques for Magnetic Field]]
**[[Sparks in Air]]
**[[Motional Emf]]
**[[Detecting a Magnetic Field]]
**[[Moving Point Charge]]
**[[Non-Coulomb Electric Field]]
**[[Electric Motors]]
**[[Solenoid Applications]]
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===Simple Circuits===
<div class="mw-collapsible-content">
*[[Components]]
*[[Steady State]]
*[[Non Steady State]]
*[[Charging and Discharging a Capacitor]]
*[[Work and Power In A Circuit]]
*[[Thin and Thick Wires]]
*[[Node Rule]]
*[[Loop Rule]]
*[[Resistivity]]
*[[Power in a circuit]]
*[[Ammeters,Voltmeters,Ohmmeters]]
*[[Current]]
**[[AC]]
*[[Ohm's Law]]
*[[Series Circuits]]
*[[Parallel Circuits]]
*[[RC]]
*[[AC vs DC]]
*[[Charge in a RC Circuit]]
*[[Current in a RC circuit]]
*[[Circular Loop of Wire]]
*[[Current in a RL Circuit]]
*[[RL Circuit]]
*[[Feedback]]
*[[Transformers (Circuits)]]
*[[Resistors and Conductivity]]
*[[Semiconductor Devices]]
*[[Insulators]]
*[[Voltage]]
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===Maxwell's Equations===
<div class="mw-collapsible-content">
*[[Gauss's Flux Theorem]]
**[[Electric Fields]]
***[[Examples of Flux Through Surfaces and Objects]]
**[[Magnetic Fields]]
**[[Proof of Gauss's Law]]
*[[Ampere's Law]]
**[[Magnetic Field of Coaxial Cable Using Ampere's Law]]
**[[Magnetic Field of a Long Thick Wire Using Ampere's Law]]
**[[Magnetic Field of a Toroid Using Ampere's Law]]
*[[Faraday's Law]]
**[[Curly Electric Fields]]
**[[Inductance]]
***[[Transformers (Physics)]]
***[[Energy Density]]
**[[Lenz's Law]]
***[[Lenz Effect and the Jumping Ring]]
**[[Lenz's Rule]]
**[[Motional Emf using Faraday's Law]]
*[[Ampere-Maxwell Law]]
*[[Superconductors]]
**[[Meissner effect]]
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===Radiation===
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*[[Producing a Radiative Electric Field]]
*[[Sinusoidal Electromagnetic Radiaton]]
*[[Lenses]]
*[[Energy and Momentum Analysis in Radiation]]
**[[Poynting Vector]]
*[[Electromagnetic Propagation]]
**[[Wavelength and Frequency]]
*[[Snell's Law]]
*[[Effects of Radiation on Matter]]
*[[Light Propagation Through a Medium]]
*[[Light Scaterring: Why is the Sky Blue]]
*[[Light Refraction: Bending of light]]
*[[Cherenkov Radiation]]
*[[Rayleigh Effect]]
*[[Image Formation]]
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===Sound===
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*[[Doppler Effect]]
*[[Nature, Behavior, and Properties of Sound]]
*[[Speed of Sound]]
*[[Resonance]]
*[[Sound Barrier]]
*[[Sound Rarefaction]]
</div>
</div>
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===Waves===
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*[[Bragg's Law]]
*[[Multisource Interference: Diffraction]]
*[[Standing waves]]
*[[Gravitational waves]]
*[[Plasma waves]]
*[[Wave-Particle Duality]]
*[[Electromagnetic Spectrum]]
*[[Color Light Wave]]
*[[The Wave Equation]]
*[[Pendulum Motion]]
*[[Transverse and Longitudinal Waves]]
*[[Planck's Relation]]
*[[interference]]
*[[Polarization of Waves]]
</div>
</div>
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===Real Life Applications of Electromagnetic Principles===
<div class="mw-collapsible-content">
*[[Electromagnetic Junkyard Cranes]]
*[[Maglev Trains]]
*[[Spark Plugs]]
*[[Metal Detectors]]
*[[Speakers]]
*[[Radios]]
*[[Ampullae of Lorenzini]]
*[[Electrocytes]]
*[[Generator]]
*[[Measuring Water Level]]
*[[Cyclotron]]
*[[Railgun]]
*[[Magnetic Resonance Imaging]]
*[[Electric Eels]]
*[[Windshield Wipers]]
*[[Galvanic Cells]]

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===Optics===
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*[[Mirrors]]
*[[Refraction]]
*[[Quantum Properties of Light]]
*[[Lasers]]

</div>
</div>

== Resources ==
* Commonly used wiki commands [https://en.wikipedia.org/wiki/Help:Cheatsheet Wiki Cheatsheet]
* A guide to representing equations in math mode [https://en.wikipedia.org/wiki/Help:Displaying_a_formula Wiki Math Mode]
* A page to keep track of all the physics [[Constants]]
* A page for review of [[Vectors]] and vector operations