Semiconductor physics is the branch of solid state physics that focuses on specific properties of semiconductors. It studies dynamics of different perturbations (mainly electrons and holes) in the semiconductor crystal and the ways to harness it in electrical circuits.

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Distance between adjacent planes in a crystal

This question has been asked before, but there doesn't seem to be a decent answer. Many sources state that " For cubic crystals with lattice constant a, the spacing d between adjacent (ℓmn) lattice ...
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Why doped silicon does not undergo electrostatic discharge?

Doped silicon is charge neutral overall, but since the extra added carriers are only weakly bounded (~45meV) they become delocalized. Since the concentration of silicon is 5-9 orders of magnitude ...
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Measuring the barrier potential of a p-n junction

Is it possible to measure the potential difference across the depletion region (barrier potential) of a p-n junction using a voltmeter?
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Widening of depletion region

Why does the width of the depletion region of a p-n junction diode increase when it's reverse biased by connecting it to an external voltage source?
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atomic concentration by lattice constant [closed]

How to determind the atomic concentration by lattice constant? As a example Crystalline germanium has the diamond lattice structure with a lattice constant $5.66*10^{-10}$ at 300K how to find the ...
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Bandgap calculation in MQW structure

In advance I want to apologize for my bad english. My question is about the calculation of a Bandgap of a multiple structure crystal. In this case: AlGaInAs. Lets assume that the distribution is: Al ...
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Effective mass vs. effective charge

In a semiconductor the effective mass multiplying the drift velocity is the result of the scattering of electrons off the ions in the crystal. I know that at least in the lowest order approximation ...
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33 views

Why is there a band gap in semiconductors but no band gap in conductors?

At this point, I understand that at least one fundamental difference between conductors and semiconductors is that in conductors, there is typically no band gap because the valence band and ...
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37 views

Einstein coefficients for emission/absorption and energy density

When dealing with a system of two energy levels $E_1$ and $E_2$ in laser theory, the following rate equations are written: $$\frac{d N_1}{dt} = A_{21}N_2 - B_{12} \rho ( \nu ) N_1 + B_{21} \rho ( \nu ...
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What is it about the “conduction band” of a material that is distinct from the valence band?

I'm taking a course in nanotech and we're discussing nanoelectronics. This has led to a discussion of conductors, semiconductors, and insulators. I have a number of lovely diagrams explaining the fact ...
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Can we increase conductivity of a conductor(like aluminium)by doping?

Silicon is a semi-conductor which converted in a good conductor by doping. So is it possible to increase conductivity of a conductor by doping?
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Any good books on the physics of semiconductor devices?

I know there are many books on semiconductor devices. But, it seems that many of them are catering to the engineers, not physicists. Namely, the books lack the theoretical depth. So, is there any ...
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Number of electrons in conduction band

As mentioned in a previous question, the number of electrons in conduction band in a semiconductor can be computed as follows: $$N = \int_{E_c}^{+\infty} g_c(E)f(E)dE$$ where $g_c(E)$ is the density ...
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A question about character table of the group Td. Group theory

I am trying to get the character table of the group Td using the basis functions already defined. I have a problem with the basis function (2z^2-x^2-y^2, x^2-y^2) because I don´t get the character -1 ...
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Difference between fermi energy level in metals and semiconductors [duplicate]

It is not exactly a question its a kind of confusion ... Here my confusion starts... what is meant by Fermi energy level?? The only definition that i found was the energy level at which the ...
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How do i calculate leakage current in passivation layer of GaN HEMT?

I want to calculate the leakage current between the passivation and encapsulation layers of the GaN HEMT which will give me information about the material
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Which is better conductor silicon or germanium and why and also which has more band gap and why and what affects the band gap in material?

want to know on what factors energy band gap depends upon.as per me it is due to electron-proton attractive forces but according to this germanium should have higher gap than silicon but germanium has ...
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52 views

Total chemical potential of electrons in pn junction

I am reading this page about electron energy concept terminology. I am trying to apply that for the pn junction in equilibrium below. Could anyone help me to see if I get it correctly? C = ...
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Existence of eigenstates in type III staggered semiconductor heterojunctions?

Two semiconductors are aligned in the type III staggered fashion and sandwiched in between infinite potentials. Can there be an eigenstate across the valence band of one material and the conduction ...
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Density of states from $k$ to $E$

Speaking about Quantum mechanics, considering the "particle in a box" condition as an approximation of the electrons condition in a semiconductor, let the material be represented by a volume $V$ with ...
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Fermi Dirac distribution and degenerate energy states

In Quantum Mechanics and in semiconductor materials, the number of electrons $N$ in conduction band is usually computed as follows: $$N = \int_{E_c}^{+\infty} g_c(E)f(E)dE$$ where $g_c(E)$ is the ...
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Why a positive voltage raises the potential energy of a positive charge and lowers the energy of a negative charge?

I am reading the relation between energy diagram and V, E (electric filed) in a semiconductor from the site (page 47-48). However, I don't quite understand this sentence below. Could anyone explain ...
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48 views

Do energy levels such as $E_c$, $E_v$ have negative values in semiconductors?

In energy band diagram of a semiconductor, do energy levels such as $E_c$, $E_v$ have negative values? Also, why electrons in semiconductor have energy? What is the formula for energy of an ...
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Energy-band diagram of forward-biased pn junction

When a p-n junction is forward biased then its energy-band diagram looks like this: What would happen if $V_a>V_{bi}$? ($V_{bi}$ is the built-in potential and $V_a$ is the externally applied ...
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Applying a voltage to a homogeneous semiconductor

Imagine that there is a homogeneous semiconductor (either a p-type or an n-type, but just one of them) uniformly doped. There is no diffusion current because of the uniform dopage, and there is no ...
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Bands in semiconductors: $E$ vs. $k$ diagram

I always thought that in a semiconductor there was one gap, one conduction band and one valence band. However, reading a book I came across this picture And now I'm very confused. Apparently there ...
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How SPAD work over Break Down voltage?

SPAD (Single Photon Avalanche Detector) works beyond Breakdown Voltage which is mentioned as Geiger Mode. But how this actually working. When bias voltage aceede breakdown voltage, generally high ...
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Why does Fermi Level change due to change in donor atom concentration?

Suppose I have a n-type semiconductor whose fermi-level lies (say) 0.2 eV below the conduction band. Why would this level change if I changed the doping by making the donor concentration (say) 4 times ...
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Why the direct band gap semiconductor get higher optical absorption coefficient than indirect band gap semiconductor

I can understand that direct band gap semiconductor doesn't need phonon to absorb light. But in the following formula: Optical absorption coefficient is proportional to the square of hv in indirect ...
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Non-constant Bandgap in a semiconductor

For a material made of two different intrinsic semiconductors (SC); $SC_A$ on the left, and $SC_B$ on the right, such that $E_{gap,A}>E_{gap,B}$, the energy band diagram would look like so: Note: ...
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Green LED Forward Voltage

Yesterday in lab, we were asked why all of our green LED had large forward voltage than expected. We expected for the forward voltage to be at around 2.1V as according to hf=Egap=eV. Yet, we ...
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26 views

Is the intrinsic carrier concentration for semiconductors an average value?

I am learning about intrinsic semiconductors, and have just come across the intrinsic carrier concentration equation - $n_{i}=BT^{3/2}e^{\cfrac{-E_{g}}{2kT}}$ Which is supposed to give the number ...
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Measurement of Quantum Hall Effect

I'm somewhat confused about the original measurement of the QHE in a Si-MOSFET, which might stem from my not understanding MOSFETs very well. In their measurement, von Klitzing et al. measure the ...
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Data transmission in optical fibers

Im reading though my Network Architecture lecture notes and it states optical fibers need a repeater every >10km. Repeaters are used to amplify digital signals but the notes do not explain or state ...
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Fermi-Dirac distribution - holes and electrons

The density of probability of an energy state $E$ being occupied by an electron is $$f(E,T)=\frac{1}{1+e^{\frac{E-E_F}{kT}}}$$ and the density of probability of an energy state being occupied by a ...
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How to calculate number of degenerate states?

For example if we need to get number of degenerate states for a particle confined in a 3D box that have energy $$E=41\frac{\pi ^2 \bar{h}^2}{2m_e L^2}$$ I know that $$E=\frac{n^2 \pi ^2 \bar{h}^2}{2 ...
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Mixed Neumann/Dirichlet BCs in Poisson-Schrodinger self-consistent solver

I'm currently in the process of writing a self-consistent Schrodinger-Poisson solver for a device heterstructure (High Mobility Electron Transistor). I am having a few difficulties however. It seems ...
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Simple calculation example of Fermi level pinning at metal-semiconductor interface

I'm having trouble calculating the following example (taken from Jasprit Singh: Semiconductor Devices, Basic Principles; John Wiley and Sons, Inc., 2001; p. 255). "Assume that at the surface of GaAs, ...
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P-n junction diode under forward bias configuration

Why there is exponential growth in current with respect to voltage in p-n junction diode under forward bias configuration?
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How long is the surface migration length of adatoms deposited by thermal evaporation in vacuum?

The deposition of metals through thermal evaporation involves the process of adatoms migrating on the substrate before its kinetic energy decreases to a certain point or before encountering a cluster. ...
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In semiconductor devices, why is quantum tunneling “fast”?

I'm reading up on semiconductor devices that rely on quantum tunneling, such as the tunnel diode and the TFET. The big advantage of these devices is apparently that "quantum tunneling is extremely ...
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What is space charge Capacitance of diode?

Most of the books say that $p$-type and $n$-type materials of diode act as parallel plates of space charge capacitance were as the depletion charges (uncovered) act as dielectric. Then why do these ...
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Electronics book for physics undergraduates

I am going through very hard time studying electronics, I studied little electronics at high school (what is diode, transistor, etc). Now in clg now I need electronics to study, I don't understand ...
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How to estimate the heat generation and the power per square cm provided the resistance and the current of a laser diode?

Laser Diodes are very tiny. So, it is making me confused in its calculation. In laboratory, the resistance of a laser diode is 10-15 ohm and the current is 80-100 mA. How could I estimate the heat ...
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How to make a monocrystalline silicon seed

I do understand that you can grow monocrystalline silicon from an initial seed but I'm lost in a chicken versus egg situation where I don't understand how you can get the seed if the only way to make ...
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How does one go about designing a substrate heater for PVD? I need to design one that can go till 1000 C in Oxygen.

Can I just use a Kanthal wire and make a pattern on a ceramic base? Wouldn't such an exposed element get shorted when I use substrates like Silicon? But wouldn't a layer of ceramic on top of the ...
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How can excite a semiconductor to make a photon just by heat in room temperature?

I want to know if a semiconductor in room temperature can excite by heat, producing photon, without any other source of energy?
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How is it guaranteed that electrical connections could be made without destroying a diode laser?

A diode laser is a tiny diode and requires a microscope to see it. Since a laser generates a good amount of heat, the diode should be destroyed with the produced heat. But it does not happen. but why ...
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Relation between interlayer tunneling amplitude and external potential in Bilayer graphene

What is the relation between interlayer tunneling amplitude ($\gamma_1$) and external potential applied ($U_{ext}$)? Is there any mathematical relation?
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Why the bandgap of inorganic semiconductors decreases with temperature?

The temperature dependence of the energy bandgap in inorganic semiconductors is given by $$E_g (T) = E_{g,0} - \frac{\alpha T^2}{T+\beta}$$ where $\alpha, \beta$ are both positive, and the (somewhat ...