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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Materials for use in a solar cell

In a solar cell, photons of the incident sunlight supply energy for excitation of electrons - a process which generates electron-hole pairs which can move under the influence of the electric field of ...
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Valence bands question

I'm currently doing solid state physics and learning about semiconductors. During the course, I have seen a lot of energy/wavevector graphs, like this one (pic from Kittel): I did not have a ...
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Charge Transport Mechanicsm of Organic Semiconductors

I understand the general concept behind inorganic semiconductors. Start with Silicon, dope the material to add an electron or a hole, and now these are free to move about in the material, creating ...
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Electric field due to delta doping in semiconductor

In a lot of textbooks about semiconductors, always seem to skip the following steps. Starting from the 'delta-doped' charge distribution: $N_D (z)= N_{D}^{2D} \delta(z-z_0)$ Where $N_{D}^{2D}$ and ...
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Conductance measurement of InAs/GaSb Quantum Spin Hall Edges

My questions are related to recent article: http://arxiv.org/ftp/arxiv/papers/1507/1507.08362.pdf I can't figure out how their sample (wafers) actually looked like. In particular I can't understand ...
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Depletion region thickness in solar cells

It is well known that typical Si solar cells are rather thick (hundreds of micrometers). Now, Si has an indirect band-gap and therefore weak optical absorption at low energies (needing a ...
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41 views

Why is GaN better than Si as a substrate for ZnO thin film?

in an attempt to grow a thin film using ZnO, I found many researches use silicon as a substrate and others use GaN. by further research I found that GaN is preferred than silicon but I don't know the ...
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98 views

What is the Al'tshuler-Aronov-Spivak effect?

What is the Al'tshuler-Aronov-Spivak effect (AAS)? How does it relate to the Aharonov-Bohm effect (AB)?
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semiconductors extrinsic and intrinsic carriers concentrations equations

I get why $n \cdot p = n_i^2$ in intrinsic semiconductors, but why is that equation also true in the case of extrinsic semiconductor? Here, $n$ is the charge density of the negatively charged ...
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Does diffusion current in semiconductor always exist?

According to what I understand, diffusion current is caused by the change in concentration of charge carriers in semiconductor (free electrons and holes) from higher concentration region to lower ...
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Semiconductor thermal equilibrium

What precisely thermal equilibrium implies in case of a semiconductor. One thing I know is that Fermi Level remains the same. But what other things does this implies, is there net current flow in case ...
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what can be the BG and dielectric constant of monolayer MoS2 in semiconducting state (2H) and in metallic state (1T)

Monolayer MoS2 is a semiconductor that can undergo an MIT (Metal to insulator) or semiconducting state to insulating state transition. The semiconducting state is referred as 2H State and the metallic ...
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376 views

What is a Dirac semimetal?

What is the precise definition of a Dirac semimetal? Is it sufficient for two bands to touch at a single k point with a linear crossing, or are more conditions required for a material to be called a ...
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60 views

Quasi-fermi levels in a solar cell?

I was wondering, if my fermi levels splits up due to n and p type doping into two fermi levels, one for the p type one for the n type, and now due to light radiation my fermi levels split up into 2 ...
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Can I use an IV curve alone to differentiate between metallic, semiconducting and insulating materials?

Assuming the size of the bandgap is expressed as resistance in the IV curve, could I tell between metals, semiconductors an insulators by only doing an IV sweep? For example very high slopes (large ...
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42 views

What's the difference between semiconductor and insulator (besides band gap)?

The typical classification of electronic materials is metal-semiconductor-insulator. Is there any actual difference between a semiconductor and an insulator, besides the size of the bandgap?
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45 views

What is the difference between Rashba coupling effect and spin orbit coupling effect

We know standard spin-orbit coupling and spin Hall effect. But what is the differences in Rashba coupling effect? What changes in Rashba coupling effect?
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What would happen if an N doped semiconductor is connected to voltage?

I've been trying to learn electronics alone, and recently stumbled upon transistors. To my understanding, transistors are like two PN junctions back to back, but with the P region very thin. This ...
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224 views

Fermi Level: chemical potential vs. electrochemical potential

In solid-state physics it is understood that the Fermi-Level is the electrochemical potential. The Fermi-Level is defined to: However, in thermodynamics this formula is referred to as the ...
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Extremely forward biased pn junction

When a pn-junction (e.g. an LED) is forward biased the height of the potential barrier is reduced... ...unless you apply a huge potential $V$, in which case the barrier gets inverted and the band ...
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114 views

What is a Fermi arc?

What is meant with a Fermi arc in the context of Weyl semimetals? Is this the just a one-dimensional Fermi surface? For example, in electron-doped graphene, the Fermi surface consists of 2 disjoint ...
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Silver vs Aluminum electrodes in silicon solar cells?

In a typical high efficiency solar cell, silver is used as a front contact and aluminum as the rear contact. Despite the lower resistivity of silver, the usage of aluminum as a front contact would ...
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31 views

How can a phosphorous ion dope silicon when it is already ionized?

In ion implantation dopant ions are directly bombarded into the semiconductor (silicon for example)? But if say P ions (P+) were implanted then it does not have an extra electron to donate into the ...
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Working principle of CIGS solar cells

can anybody explain me how CIGS solar cells working.when photon hits the window layer is there any EHP created or ,that buffer layer lets pass photon energy to absorber layer.please explain me by ...
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CIGS Photo Voltaic cells

Why n type layer is on top of p type layer in CIGS solar cells? does it do anything with wavelength of photon and thickness of window and absorber layer?
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164 views

Calculation of RMS current in half wave rectifier

While calculating RMS current in half wave rectifier, why we will consider only half wave that means only we consider the limits 0 to pi. But here RMS current is for AC input..so why don't we consider ...
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156 views

Are there measurable quantities which directly depends on the Fermi velocity?

The dispersion relation of electrons in, for example, graphene exhibits Dirac cones. The dispersion relation of a Dirac point at $\mathbf{k}=\mathbf{K}$ is linear in the momentum magnitude: $$E=\pm ...
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Does doping and size determine the characteristics of a semi-conductor?

Does the maximum voltage and current that a semiconductor can withstand (without being damaged) depend upon the size and doping of the semiconductor? If so, then please explain, 1.What is the reason ...
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What is the smallest possible electronic transistor?

Computers have increased in processing power mainly due to the miniaturization of transistors. I read recently that IBM, with great difficulty, shrank circuits from 14nm to 7nm but progress seems to ...
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66 views

Why the optical gap is not identical to the charge gap?

The optical gap is the photon energy required to create an exciton (in a solar cell for example). The charge gap (aka electrical gap) is the energy (voltage) required to create a photon (in an LED for ...
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65 views

Why is Fermi-Dirac type of distribution used in semiconductors?

We assume that distribution of electrons follows Fermi-Dirac distribution / statistics in semiconductor model which will help to find the concentrations of electron and holes and the relationship ...
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91 views

What causes this IR emission in UV 365nm LED?

I've just got access to spectrometer and measuring spectrum of everything. But when I took a look at 365nm UV led from chinese UV flashlight I got something really strange - it had some IR at exactly ...
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24 views

Nature of photoluminescence at a semiconductor heterojunction

Do I understand it correctly that photoluminescence at a semiconductor heterojunction occurs because of intralayer recombination? If so, why can't photoluminescence occur because of interlayer ...
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51 views

Why do semiconductors remain neutral outside the depletion region?

Why there is a sharp cut off of the charged region outside the depletion region, like on this image? For example why don't electrons on the conduction band in the n-type side rush towards the ...
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Why does normal incidence eliminate the photocarrier effect radiation in this experiment?

Here's a paper in which they use GaAs crystals at a few orientations to produce THz radiation, by means of Optical Rectification (OR). That's actually not what this question is about, though. They ...
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Adding thin films to a Peltier Device

I am using a peltier device maintaining a constant gradient by applying a voltage/current. My current setup is: Cold Side Peltier Device Hot Side CPU fan Was just wondering forgetting time ...
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26 views

Is the electron-hole pair a 1D quantum oscillator or 3D oscillator

I'm trying to use fluctuation dissipation theorem to describe spontaneous photon emission process by electron-hole recombination in semiconductor material. I notice that all the references using such ...
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59 views

what is the source of nonlinear behaviour of semiconductor transistor?

It is known that semiconductor transistor can be used as a switch as well as amplifier. How does the linear amplifying characteristic and non-linear switching characteristic come in a single system?
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e-e scattering rate in normal fermi liquid and in graphene

In Ashcroft/Mermin's solid state physics, in equation (17.64) they argued that: We expect from lowest-order perturbation theory (Born approximation) that $\tau$ will depend on the ...
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Why are band maxima / minima often (always?) at high-symmetry points?

(inspired by this question.) In every semiconductor that I can think of, the valence band maximum and conduction band minimum are at a high-symmetry point in the Brillouin Zone (BZ). Often the BZ ...
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How does phonon scattering change the distribution function?

For a one-dimensional structure, we know that the modified distribution function has the following energy dependency in equilibrium: \begin{equation} Z(\varepsilon)\,f(\varepsilon) = ...
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Can I catch a single photon with webcam's CMOS or CCD sensors?

I thought it would be nice to capturing single photons using a webcam's sensor due to simplicity. I've read that ccd and cmos sensors have a certain percent of quantum efficiency. What about ...
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Reverse recovery current + diode

The reverse recovery current of a diode is due to accumulated charges in the P and N region during it forward stat. I want to know this current is a diffusion current or a drift current?
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167 views

Relationship between Fermi Energy and Average Energy

Electrons are in a one dimensional box of length 2L. What is the relationship between Ef, the fermi energy and E, the average energy? The answer is Ef/3 I looked up the formula for the relationship: ...
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Interpretation of the diode constant in a LED

For a real diode the current as function of the potential difference between its terminals (for big enough voltage) is given by: $$I=A e^{\frac{eV-E}{\eta k_B T}} \tag{1}$$ So in the case of LEDs ...
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Is $\kappa_e$ caused by charge-carrier transport or electron transport?

$\kappa$ usually symbolises thermal conductivity, a material's ability to conduct heat. $\kappa$ can be expressed with other partial thermal conductivities: $\kappa=\kappa_e+\kappa_{ph}+...$ where ...
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When do optical phonon branches arise?

As far as I understand from what I'm studying, only when you have more than one kind of atom in the lattice structure, will the phonon have an optical branch, or else it should not have an optical ...
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45 views

Can you dope insulators

The question came in my mind because of the definition of doping. For p-type we create holes just above the valence band. This creates holes in the valence band which can contribute to conduction. ...
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Smallest theoretical process node for ASIC

This is just a curiosity question but I remember when 90nm seemed insane so I was wondering what the theoretical limit would be on process size before we couldn't go any smaller. Wiki tells me that ...
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437 views

Barrier potential for germanium, silicon and gallium arsenide

Where did the barrier potentials for Germanium (0.3V), Silicon (0.7V) and Germanium Arsenide (1.2V) come from? How was it derived?