Semiconductor Devices - Revision history

Hmia22: /* History */

2025-04-13T22:27:04Z

History

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	'''2000'''		'''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."		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."

			'''2010s-2020s'''
			The semiconductor industry experienced rapid innovation driven by the demand for smaller, faster, and more energy-efficient devices. The introduction of FinFET (Fin Field Effect Transistor) technology enabled further miniaturization beyond the limits of traditional planar transistors, significantly improving performance and reducing power consumption. This period also saw the expansion of mobile and IoT devices, which increased global reliance on semiconductor chips. Additionally, Taiwan Semiconductor Manufacturing Company (TSMC) and Samsung emerged as leaders in advanced chip fabrication, pushing technology nodes below 5 nanometers.

			'''2020s-present'''
			Semiconductors have become central to geopolitical strategies, national security, and global supply chains, especially highlighted during the COVID-19 pandemic, which exposed vulnerabilities in semiconductor manufacturing and distribution. In response, governments around the world, including the United States, European Union, and China, launched major initiatives to invest in domestic semiconductor production. Meanwhile, emerging technologies such as AI accelerators, quantum computing, and 3D integrated circuits are reshaping the semiconductor landscape. In 2022, the United States passed the CHIPS and Science Act, a multibillion dollar initiative to revitalize American chip manufacturing and research leadership.

	[[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.]]		[[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.]]

Hmia22: /* A Conceptual Model */

2025-04-13T22:24:39Z

A Conceptual Model

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	===A Conceptual Model===		===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.		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.

			The size of the band gap (𝐸 gap) is a defining feature of semiconductor materials and determines their electrical and optical properties. Materials with smaller band gaps, such as silicon or germanium, require less thermal energy to excite electrons from the valence band to the conduction band, making them effective at room temperature. In contrast, insulators have much larger band gaps, which prevent significant electron excitation under normal conditions. This small energy requirement in semiconductors allows for controlled conduction and is also the basis for their behavior in optoelectronic applications such as photodetectors, LEDs, and solar cells. The ability to engineer the band gap through material choice or nanostructuring is a powerful tool in the design of modern electronic and photonic devices.

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

Hmia22: /* Detecting Doping */

2025-04-13T22:20:57Z

Detecting Doping

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	Secondary ion mass spectroscopy (SIMS) is a very powerful technique for the analysis of impurities in solids. SIMS can be utilized for semiconductor dopant profiling. The technique relies on removal of material from a solid by sputtering and on analysis of the sputtered ionized species; all elements are detected. SIMS can detect dopant densities as low as 10^14 cm^-3. The dopant density profile that is generated is based on the ion signal versus time plot. The time axis is converted to a depth axis by measuring the depth of the crater at the end of the measurement assuming a constant sputtering rate. For example, boron is implanted into silicon at a given energy and dose to create a standard. The secondary ion signal is calibrated by assuming the total amount of boron in the sample to equal to the implanted boron. The unknown sample of B implanted into silicon is then compared to the standard. However, there is limited dynamic range of the SIMS instrument that can contribute to slightly deeper junctions and discrepancies in the lowly doped portions of the profile. When sputtering from a highly doped region to a lowly doped region, the crater walls still contain the entire doping density profile. SIMS also measures total dopant density, regardless of activation. Thus going back to the silicon-boron example, the dopant profile shows dependence of electrical activation of boron implanted into silicon on implant dose and activation temperature.		Secondary ion mass spectroscopy (SIMS) is a very powerful technique for the analysis of impurities in solids. SIMS can be utilized for semiconductor dopant profiling. The technique relies on removal of material from a solid by sputtering and on analysis of the sputtered ionized species; all elements are detected. SIMS can detect dopant densities as low as 10^14 cm^-3. The dopant density profile that is generated is based on the ion signal versus time plot. The time axis is converted to a depth axis by measuring the depth of the crater at the end of the measurement assuming a constant sputtering rate. For example, boron is implanted into silicon at a given energy and dose to create a standard. The secondary ion signal is calibrated by assuming the total amount of boron in the sample to equal to the implanted boron. The unknown sample of B implanted into silicon is then compared to the standard. However, there is limited dynamic range of the SIMS instrument that can contribute to slightly deeper junctions and discrepancies in the lowly doped portions of the profile. When sputtering from a highly doped region to a lowly doped region, the crater walls still contain the entire doping density profile. SIMS also measures total dopant density, regardless of activation. Thus going back to the silicon-boron example, the dopant profile shows dependence of electrical activation of boron implanted into silicon on implant dose and activation temperature.

			In addition to quantifying dopant concentrations, SIMS provides excellent depth resolution, making it particularly effective for analyzing shallow junctions in modern semiconductor devices. This is important for applications in advanced CMOS technologies, where junction depths are often on the nanometer scale. SIMS can detect both intentional dopants and unintended contaminants, such as metals or residual elements from the fabrication process, which may affect device performance or yield. While SIMS is destructive due to sputtering, its high sensitivity and wide dynamic range make it a go-to method for semiconductor process monitoring and failure analysis. By correlating SIMS profiles with electrical measurements, researchers and engineers can gain a more complete understanding of dopant behavior and diffusion mechanisms in semiconductor materials.

	[[File:Sims-technique-schematic.png\|frame\|none\|left\|Example of SIMS]]		[[File:Sims-technique-schematic.png\|frame\|none\|left\|Example of SIMS]]

Hmia22: /* Semiconductors & Applications in Solid-State Physics */

2025-04-13T22:18:07Z

Semiconductors & Applications in Solid-State Physics

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	===Semiconductors & Applications in Solid-State Physics===		===Semiconductors & Applications in Solid-State Physics===

	~~The~~ key principle ~~that is often used~~ in solid-state physics is the carrier effective mass. This refers to the mass a particle ~~(within the~~ semiconductor~~) seems to have~~ when interacting with other identical particles in a thermal distribution. ~~This constant is simplified version~~ of ~~the~~ band theory and ~~influences~~ measurable properties of ~~a solid, including the efficiency of the devices that semiconductors are used in for example~~, solar cell efficiency and integrated circuit speed. ~~So,~~ how ~~do we actually measure the~~ carrier effective ~~masses in a semiconductor~~?		A key principle in solid-state physics is the carrier effective mass. This refers to the apparent mass that a particle, such as an electron or hole in a semiconductor, exhibits when interacting with other identical particles in a thermal distribution. The concept simplifies aspects of band theory and plays an important role in determining measurable properties of solids, such as solar cell efficiency and integrated circuit speed. But how is carrier effective mass actually measured?

	~~Large parts~~ of the simplicity of the free electron gas model can be ~~saved~~ by assigning effective masses to ~~the~~ carriers. ~~Only~~ electrons and holes at the band edges (characterized by a wave vector ~~kex~~) participate in the generation - recombination ~~process~~ that ~~is the hallmark of semiconductors~~. ~~A particle's~~ effective mass is the mass ~~that it seems~~ to have when responding to forces, or ~~the mass that it seems to have~~ when ~~interacting with other identical particles~~ in ~~a thermal distribution. One of the results from~~ the ~~band theory~~ of ~~solids is that the movement of particles over long distances~~ can ~~be very different~~ from ~~their~~ motion in a vacuum. ~~The effective mass is a~~ quantity ~~that~~ is used to ~~simplify band structures by modeling~~ the behavior of a free ~~particle~~ with ~~that~~ mass. ~~Sometimes the effective mass can be considered to be~~ a ~~simple~~ constant of a material~~, however~~, the ~~value of~~ effective mass ~~depends on the purpose for which it is used, and~~ can vary ~~depending~~ on ~~a number of~~ factors. For electrons or ~~electron~~ holes ~~in a solid~~, ~~the~~ effective mass is ~~usually stated~~ in ~~units~~ of the rest mass ~~of an electron,~~ me (9.~~11×10−31~~ kg)~~. In these units it is usually in the range~~ 0.01 to 10, ~~but~~ can ~~also be lower or higher—for example, reaching~~ 1,000 ~~in exotic heavy fermion materials~~, or ~~anywhere~~ from zero to infinity ~~(depending on definition)~~ in graphene. ~~The~~ effective mass of ~~a semiconductor is obtained by fitting~~ the ~~actual electron diagram around~~ the conduction band minimum or ~~the~~ valence band maximum by a parabola ~~- this is called an E-K diagram (shown below)~~. ~~It shows~~ the ~~relationship between~~ the ~~energy and momentum of available quantum mechanical states for electrons in~~ the ~~material~~. As ~~it simplifies the~~ more ~~general~~ band theory, the electronic effective mass ~~can be seen as an important basic~~ parameter ~~that influences measurable properties of a solid, including everything from the efficiency of a solar cell to the speed of an integrated circuit~~.		Much of the simplicity of the free electron gas model can be retained by assigning effective masses to charge carriers. In semiconductors, only electrons and holes near the band edges, characterized by a specific wave vector (kₑₓ), participate in the generation and recombination processes that are central to semiconductor function. The effective mass is essentially the mass a particle appears to have when responding to external forces or when moving in the periodic potential of a crystal lattice, which can differ significantly from its motion in a vacuum.

			This quantity is used to approximate the complex behavior of electrons in a crystal by modeling them as free particles with an altered mass. While sometimes treated as a constant for a given material, the effective mass can vary based on factors such as direction, temperature, and application. For electrons or holes, effective mass is typically expressed in terms of the electron rest mass (me = 9.11 × 10⁻³¹ kg), with values commonly ranging from 0.01 to 10 me. However, in special materials like heavy fermion systems, it can reach up to 1,000 me, or even vary from zero to infinity in systems like graphene.

			To determine effective mass, scientists fit the curvature of the energy-momentum relationship near the conduction band minimum or valence band maximum with a parabola. This approach allows the extraction of the effective mass from the local band structure. As a simplified interpretation of more complex band theory, the electronic effective mass remains a fundamental parameter influencing key performance characteristics in semiconductor-based devices.

	===Detecting Doping===		===Detecting Doping===

Hmia22: /* Semiconductors & Applications in Solid-State Physics */

2025-04-13T22:16:27Z

Semiconductors & Applications in Solid-State Physics

← Older revision		Revision as of 18:16, 13 April 2025
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	Large parts of the simplicity of the free electron gas model can be saved by assigning effective masses to the carriers. Only electrons and holes at the band edges (characterized by a wave vector kex) participate in the generation - recombination process that is the hallmark of semiconductors. A particle's effective mass is the mass that it seems to have when responding to forces, or the mass that it seems to have when interacting with other identical particles in a thermal distribution. One of the results from the band theory of solids is that the movement of particles over long distances can be very different from their motion in a vacuum. The effective mass is a quantity that is used to simplify band structures by modeling the behavior of a free particle with that mass. Sometimes the effective mass can be considered to be a simple constant of a material, however, the value of effective mass depends on the purpose for which it is used, and can vary depending on a number of factors. For electrons or electron holes in a solid, the effective mass is usually stated in units of the rest mass of an electron, me (9.11×10−31 kg). In these units it is usually in the range 0.01 to 10, but can also be lower or higher—for example, reaching 1,000 in exotic heavy fermion materials, or anywhere from zero to infinity (depending on definition) in graphene. The effective mass of a semiconductor is obtained by fitting the actual electron diagram around the conduction band minimum or the valence band maximum by a parabola - this is called an E-K diagram (shown below). It shows the relationship between the energy and momentum of available quantum mechanical states for electrons in the material. As it simplifies the more general band theory, the electronic effective mass can be seen as an important basic parameter that influences measurable properties of a solid, including everything from the efficiency of a solar cell to the speed of an integrated circuit.		Large parts of the simplicity of the free electron gas model can be saved by assigning effective masses to the carriers. Only electrons and holes at the band edges (characterized by a wave vector kex) participate in the generation - recombination process that is the hallmark of semiconductors. A particle's effective mass is the mass that it seems to have when responding to forces, or the mass that it seems to have when interacting with other identical particles in a thermal distribution. One of the results from the band theory of solids is that the movement of particles over long distances can be very different from their motion in a vacuum. The effective mass is a quantity that is used to simplify band structures by modeling the behavior of a free particle with that mass. Sometimes the effective mass can be considered to be a simple constant of a material, however, the value of effective mass depends on the purpose for which it is used, and can vary depending on a number of factors. For electrons or electron holes in a solid, the effective mass is usually stated in units of the rest mass of an electron, me (9.11×10−31 kg). In these units it is usually in the range 0.01 to 10, but can also be lower or higher—for example, reaching 1,000 in exotic heavy fermion materials, or anywhere from zero to infinity (depending on definition) in graphene. The effective mass of a semiconductor is obtained by fitting the actual electron diagram around the conduction band minimum or the valence band maximum by a parabola - this is called an E-K diagram (shown below). It shows the relationship between the energy and momentum of available quantum mechanical states for electrons in the material. As it simplifies the more general band theory, the electronic effective mass can be seen as an important basic parameter that influences measurable properties of a solid, including everything from the efficiency of a solar cell to the speed of an integrated circuit.

	~~[[File:IMG_0585.jpg\|Diagram of an EK diagram\|350 px\|]]~~

	===Detecting Doping===		===Detecting Doping===

Hmia22: /* Semiconductors & Applications in Solid-State Physics */

2025-04-13T22:14:29Z

Semiconductors & Applications in Solid-State Physics

← Older revision		Revision as of 18:14, 13 April 2025
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	Large parts of the simplicity of the free electron gas model can be saved by assigning effective masses to the carriers. Only electrons and holes at the band edges (characterized by a wave vector kex) participate in the generation - recombination process that is the hallmark of semiconductors. A particle's effective mass is the mass that it seems to have when responding to forces, or the mass that it seems to have when interacting with other identical particles in a thermal distribution. One of the results from the band theory of solids is that the movement of particles over long distances can be very different from their motion in a vacuum. The effective mass is a quantity that is used to simplify band structures by modeling the behavior of a free particle with that mass. Sometimes the effective mass can be considered to be a simple constant of a material, however, the value of effective mass depends on the purpose for which it is used, and can vary depending on a number of factors. For electrons or electron holes in a solid, the effective mass is usually stated in units of the rest mass of an electron, me (9.11×10−31 kg). In these units it is usually in the range 0.01 to 10, but can also be lower or higher—for example, reaching 1,000 in exotic heavy fermion materials, or anywhere from zero to infinity (depending on definition) in graphene. The effective mass of a semiconductor is obtained by fitting the actual electron diagram around the conduction band minimum or the valence band maximum by a parabola - this is called an E-K diagram (shown below). It shows the relationship between the energy and momentum of available quantum mechanical states for electrons in the material. As it simplifies the more general band theory, the electronic effective mass can be seen as an important basic parameter that influences measurable properties of a solid, including everything from the efficiency of a solar cell to the speed of an integrated circuit.		Large parts of the simplicity of the free electron gas model can be saved by assigning effective masses to the carriers. Only electrons and holes at the band edges (characterized by a wave vector kex) participate in the generation - recombination process that is the hallmark of semiconductors. A particle's effective mass is the mass that it seems to have when responding to forces, or the mass that it seems to have when interacting with other identical particles in a thermal distribution. One of the results from the band theory of solids is that the movement of particles over long distances can be very different from their motion in a vacuum. The effective mass is a quantity that is used to simplify band structures by modeling the behavior of a free particle with that mass. Sometimes the effective mass can be considered to be a simple constant of a material, however, the value of effective mass depends on the purpose for which it is used, and can vary depending on a number of factors. For electrons or electron holes in a solid, the effective mass is usually stated in units of the rest mass of an electron, me (9.11×10−31 kg). In these units it is usually in the range 0.01 to 10, but can also be lower or higher—for example, reaching 1,000 in exotic heavy fermion materials, or anywhere from zero to infinity (depending on definition) in graphene. The effective mass of a semiconductor is obtained by fitting the actual electron diagram around the conduction band minimum or the valence band maximum by a parabola - this is called an E-K diagram (shown below). It shows the relationship between the energy and momentum of available quantum mechanical states for electrons in the material. As it simplifies the more general band theory, the electronic effective mass can be seen as an important basic parameter that influences measurable properties of a solid, including everything from the efficiency of a solar cell to the speed of an integrated circuit.

	[[File:~~IMG 2424~~.jpg\|Diagram of an EK diagram\|350 px\|]]		[[File:IMG_0585.jpg\|Diagram of an EK diagram\|350 px\|]]

	===Detecting Doping===		===Detecting Doping===

Hmia22 at 22:10, 13 April 2025

2025-04-13T22:10:18Z

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	Semiconductor devices are electronic components that exploit the electrical properties of semiconducting materials. Common semiconductors include silicon, germanium, gallium arsenide, and certain organic compounds. These materials have electrical conductivity levels between those of conductors such as metals and insulators such as ceramics, making them ideal for controlled current flow. While semiconductors are often pure elements, impurities are intentionally introduced through a process called doping to modify their conductivity. Pure, undoped semiconductors are referred to as intrinsic, whereas doped semiconductors are known as extrinsic. Intrinsic semiconductors generally have fewer charge carriers—free electrons or holes—and are therefore less conductive. Extrinsic semiconductors can be engineered for higher or lower conductivity depending on the type and level of doping.		Semiconductor devices are electronic components that exploit the electrical properties of semiconducting materials. Common semiconductors include silicon, germanium, gallium arsenide, and certain organic compounds. These materials have electrical conductivity levels between those of conductors such as metals and insulators such as ceramics, making them ideal for controlled current flow. While semiconductors are often pure elements, impurities are intentionally introduced through a process called doping to modify their conductivity. Pure, undoped semiconductors are referred to as intrinsic, whereas doped semiconductors are known as extrinsic. Intrinsic semiconductors generally have fewer charge carriers—free electrons or holes—and are therefore less conductive. Extrinsic semiconductors can be engineered for higher or lower conductivity depending on the type and level of doping.

	The conductivity of semiconductors is also influenced by environmental factors such as temperature. Electrical conductivity depends on two key factors: charge-carrier mobility and the concentration of mobile charge carriers. Charge carriers, which are free electrons or holes, move through a material under an applied voltage, and their mobility refers to the speed of this movement. While metals exhibit consistent charge-carrier concentrations, semiconductors show strong temperature dependence, especially intrinsic ones. As temperature increases, electrons gain enough energy to jump from the valence band to the conduction ~~band—overcoming~~ the band ~~gap—which~~ increases conductivity. In extrinsic semiconductors, doping can either enhance or reduce this effect.		The conductivity of semiconductors is also influenced by environmental factors such as temperature. Electrical conductivity depends on two key factors: charge-carrier mobility and the concentration of mobile charge carriers. Charge carriers, which are free electrons or holes, move through a material under an applied voltage, and their mobility refers to the speed of this movement. While metals exhibit consistent charge-carrier concentrations, semiconductors show strong temperature dependence, especially intrinsic ones. As temperature increases, electrons gain enough energy to jump from the valence band to the conduction band, overcoming the band gap, which increases conductivity. In extrinsic semiconductors, doping can either enhance or reduce this effect.

	Because of their low cost, reliability, controllable conductivity, and compact size, semiconductors are used in a wide variety of applications. They are found in power devices, optical sensors, light emitters, and, most importantly, microelectronic systems. Their ability to handle a broad range of current and voltage makes them essential in communication devices, consumer electronics, data processing, and industrial control systems		Because of their low cost, reliability, controllable conductivity, and compact size, semiconductors are used in a wide variety of applications. They are found in power devices, optical sensors, light emitters, and, most importantly, microelectronic systems. Their ability to handle a broad range of current and voltage makes them essential in communication devices, consumer electronics, data processing, and industrial control systems

Hmia22 at 22:09, 13 April 2025

2025-04-13T22:09:21Z

← Older revision		Revision as of 18:09, 13 April 2025
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	===What are Semiconductors?===		===What are Semiconductors?===

			Semiconductor devices are electronic components that exploit the electrical properties of semiconducting materials. Common semiconductors include silicon, germanium, gallium arsenide, and certain organic compounds. These materials have electrical conductivity levels between those of conductors such as metals and insulators such as ceramics, making them ideal for controlled current flow. While semiconductors are often pure elements, impurities are intentionally introduced through a process called doping to modify their conductivity. Pure, undoped semiconductors are referred to as intrinsic, whereas doped semiconductors are known as extrinsic. Intrinsic semiconductors generally have fewer charge carriers—free electrons or holes—and are therefore less conductive. Extrinsic semiconductors can be engineered for higher or lower conductivity depending on the type and level of doping.

			The conductivity of semiconductors is also influenced by environmental factors such as temperature. Electrical conductivity depends on two key factors: charge-carrier mobility and the concentration of mobile charge carriers. Charge carriers, which are free electrons or holes, move through a material under an applied voltage, and their mobility refers to the speed of this movement. While metals exhibit consistent charge-carrier concentrations, semiconductors show strong temperature dependence, especially intrinsic ones. As temperature increases, electrons gain enough energy to jump from the valence band to the conduction band—overcoming the band gap—which increases conductivity. In extrinsic semiconductors, doping can either enhance or reduce this effect.

	~~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. They have a good conductivity between conductors (these tend to be metals) and nonconductors (these insulators tend to be ceramics). Semiconductors do not have to originate organically - the most common semiconductor material are pure elements such as silicon and germanium, but impurities are often added to control the conductivity levels. This process is called doping. The doped semiconductors are called extrinsic semiconductors while pure, impurity-free semiconductors are called intrinsic semiconductors. Intrinsic semiconductors are less conductive than metals as they have a lower amount of charge carriers, or electrons or holes, that can move across the band gap. Extrinsic semiconductors can have higher or lower conductivity depending on the doping.		Because of their low cost, reliability, controllable conductivity, and compact size, semiconductors are used in a wide variety of applications. They are found in power devices, optical sensors, light emitters, and, most importantly, microelectronic systems. Their ability to handle a broad range of current and voltage makes them essential in communication devices, consumer electronics, data processing, and industrial control systems


	The conductivity of these semiconductors can also be impacted by environmental changes such as temperature changes. Electrical conductivity depends on two factors: charge-carrier mobility and the concentration of mobile charge carriers. Charge carriers are free electrons or holes that are able to move freely throughout a material, and their mobility is the speed at which these electrons move in a certain direction under the application of a voltage. The free electrons are responsible for determining a current as a current is defined as the rate of electrons flowing through a material in a unit of time. In semiconductors, the charge carrier mobility is negligible as the temperature directly impacts mainly the charge carrier concentration. The band gap theory helps explain how charge carriers move in semiconductors. Unlike metals, semiconductors have a gap between the conduction band and the valence band where the electrons sit without excitation. As temperature increases, these electrons gain energy until they have enough energy to cross the band gap and into the conduction band, decreasing resistivity and increasing conductivity. This behavior is observed mainly in intrinsic semiconductors. In extrinsic semiconductors, the type of doping can affect the conductivity negatively or positively.


	~~Due to~~ low cost, reliability, ~~ability to control~~ conductivity, 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:Intelthing.jpg\|frame\|border\|right\|A raw board with many transistors in it!]]
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	[[File:p-type.png\|frame\|none\|left\|P-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.		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.
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	[[File:conceptual.png\|frame\|none\|left\|A Conceptual Model of the Semiconductor]]		[[File:conceptual.png\|frame\|none\|left\|A Conceptual Model of the Semiconductor]]


	===A Computational Model===		===A Computational Model===
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	[[Image:BJT NPN symbol (case).svg\|75px\|thumb\|NPN BJT]]		[[Image:BJT NPN symbol (case).svg\|75px\|thumb\|NPN BJT]]
	[[Image:BJT PNP symbol (case).svg\|75px\|thumb\|PNP 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.		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.

Hmia22 at 21:42, 10 April 2025

2025-04-10T21:42:03Z

← Older revision		Revision as of 17:42, 10 April 2025
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	~~Last edited by~~ Irene Dumitriu (Spring 2024)		Irene Dumitriu (Spring 2024), Mia Harrell (Spring 2025)

Idumitriu3: /* Determining Semiconductor Resistivity and Conductivity */

2024-04-15T03:30:21Z

Determining Semiconductor Resistivity and Conductivity

← Older revision		Revision as of 23:30, 14 April 2024
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	===Determining Semiconductor Resistivity and Conductivity===		===Determining Semiconductor Resistivity and Conductivity===

	Methods for determining the resistivity and conductivity of material involve galvanostatic or potentiostatic tests. In a galvanostatic test, a constant current is applied and the voltage is measured. In a potentiostatic test, a constant voltage is applied and the current is measured. An electrochemical analyzer can be used with either a 2-point or 4-point method. With the 2-point method, there can be contact resistance between the material and the wires, falsely increasing the resistivity. The 4-point technique overcomes this issue by using four wires. A current is conducted and measured through the endpoints of the bar while two wires are connected to the inner points of the bar so that they can measure voltage produced across the inner bar. Once the data is collected, Ohm’s law can be used to calculate the ~~resistivity with the voltage and~~ resistance where the resistance is ~~the~~ 1/slope of the current vs. voltage graph.		Methods for determining the resistivity and conductivity of material involve galvanostatic or potentiostatic tests. In a galvanostatic test, a constant current is applied and the voltage is measured. In a potentiostatic test, a constant voltage is applied and the current is measured. An electrochemical analyzer can be used with either a 2-point or 4-point method. With the 2-point method, there can be contact resistance between the material and the wires, falsely increasing the resistivity. The 4-point technique overcomes this issue by using four wires. A current is conducted and measured through the endpoints of the bar while two wires are connected to the inner points of the bar so that they can measure the voltage produced across the inner bar. Once the data is collected, Ohm’s law can be used to calculate the resistance where the resistance is 1/slope of the current vs. voltage graph. Resistivity is
			<math>
			𝜌 = R \ {\frac{A}{L}}
			</math>, where R is the resistance, A is the cross-sectional area, and L is the length. Conductivity is
			<math>
			𝜎 = 𝜌^{-1}
			</math>.

	[[File:2pp_vs_4pp_resistivity.png\|frame\|border\|center\|The 2-point method vs. the 4-point method in determining the resistivity of sample.]]		[[File:2pp_vs_4pp_resistivity.png\|frame\|border\|center\|The 2-point method vs. the 4-point method in determining the resistivity of sample.]]

			However, this method only works for bulk materials. If the semiconductor is in the form of a thin film, then a 4-point colinear probe can be used instead. The method works by measuring the resistance of the material by applying a current through the two outer probes and measuring the voltage of the two inner probes. The resistivity and conductivity calculations are more complicated for thin films as correction factors need to be applied in order to adjust the data for the film thickness, the probe's placement, and other factors. For example, a correction factor needs to be used when the thickness is less than or equal to half the probe spacing. If this is true, then the resistivity is
			<math>
			𝜌 = (R)\ (2𝜋)\ (s)\ (F1)
			</math> where s is the spacing and F1 is the correction factor.

	===A Mathematical Model===		===A Mathematical Model===