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 affect it.

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List of experimental band gap

does anyone know where one can find a list, database, book of experimental bandgap values of semiconductors? Is there such a collection? Or do I need to scour papers one at a time to get the values?
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What the heck is negative effective mass?

I am reading this book:Solid State Electronic Devices by Ben G Streetman and Sanjay Kumar Banerjee. I have some doubts in the article 3.2.2 Effective mass. In this the aythors say that ...
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Working of a phototransistor

Can anyone explain how photogenerated current in the base gets amplified in a phototransistor. If you use band energy diagram, then I would understand more quickly and clearly.
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How does temperature affect photovoltaics (PV) efficiency?

I know that photovoltaic panels are more efficient at lower temperatures: As the temperature increases, the output voltage decreases. I am looking for an explanation of the mechanism behind this ...
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How can I simulate a model electronic hole?

Suppose I can solve time-dependent Schrödinger equation for several 1D particles (currently 3). I'd like to see, what an electronic hole is and how it behaves — in a series of numerical experiments. ...
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Silicon atom: How is it replaced by a Phosphorous (or Boron) atom?

My book says: A pure semiconductor at room temperature possesses free electrons and holes but their number is so small that conductivity offered by the pure semiconductor cannot be made of ...
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Why isn't there a potential difference across a disconnected diode?

I know this question sounds silly, as if there was a potential difference a current would be created when the terminals are connected together and this would mean energy has come from somewhere. The ...
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Why is an exciton only observed when we excite to the conduction band and not to other electronic level inside the bandgap?

Excitons can be observed when we excite electrons to the conduction band. I don't know about excitons being observed when we excite the electrons to an electronic level that would eventually be in ...
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Possible to calculate carrier lifetime with doping concentrations?

I'm working on a problem involving a silicon semiconductor. A PN junction is created with $N_a = 5\cdot10^{14}$ throughout the entire semiconductor, and is doped with $N_d = 2\cdot10^{15}$ on the N ...
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The skin effect and the reflectivity of gold

I am simulating a waveguide in COMSOL, a FEM solver. My model looks like this (it is similar to a standard Quantum Cascade Laser geometry): Therefore there is a very thin (30nm) layer of gold ...
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Donors/Acceptors in Metal Oxides

Can anyone explain to me why most articles describe chromium as an acceptor in titanium dioxide? In TiO2, titanium has the charge state Ti$^{4+}$ and oxygen has the charge state O$^{2-}$. When Cr ...
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Is carrier charge density and carrier mobility constant in a given material?

If we assume the semi-conductor is doped by a variable amount, is there some way I can look up carrier charge density for the material in a reference somewhere? What about carrier mobility?
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CCD's and the photoelectric effect

Do charge coupled devices as found in telescopes use the photoelectric effect if not what eles librates the electons. Also what is charge intergration in reation to CCD's.
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Does Saturation velocity in semiconductors have a relation with the wavelength in which the peak in the absorption spectrum occurs?

Saturation velocity is the maximum velocity a charge carrier in a semiconductor, generally an electron, attains in the presence of very high electric fields. (source) I want to know if the ...
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Why does a window layer is on top of the absorber layer in solar cells and not below it?

In solar cells there is a p-n junction. P-type semiconductor (for example CdTe) is often absorber layer because of its carrier lifetime and mobilities. In case of CdS/CdTe, CdS is n-type window layer ...
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Is the valence band neutral?

While studying about band theory of semiconductors, I observed that when the electrons were excited from the valence band to the conduction band, they left behind holes in the valence band. From my ...
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What are the differences between supperlattices and Multiple Quantum Wells Semiconductor Structures?

Semiconductor Optoelectronics: What are the differences between multiple Quantum Wells and supperlattices.
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Why does overclocking a CPU cause it to generate more heat?

It seems odd to me that overclocking a CPU causes it to consume more energy. The amount of energy flowing through the CPU should be related to the average number of 'gates' (or transistors) that ...
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PN Junction. Germanium VS Silicon

As far as I understood, when we connect P and N materials, electrons from N drift to P, thus create negative ions in P and positive ions in N. => electric field (barrier potential) must depend on an ...
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Effective mass of a particle

I was reading about concept of effective mass on Wikipedia and came across the line that effective mass of a particle can be negative and even zero. How is this possible?
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How do the effects of semiconductor doping affect the Hall effect?

For instance, consider number 4 and 5 in the following sample: Using the right hand rule, B points downwards, conventional current points to the right (because of the 5V battery), and therefore, ...
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Fermi level in equilibrium and non-equilibrium situations

Why do the Fermi level for electrons and holes coincide in equilibrium condition and why do they separate as quasi-Fermi levels in non equilibrium situations?
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n-p-n p-n-p and n-n-n heterostructure for LED

I was studying LED Heterostructures and I found out that my book is always giving reference to p-p-n type heterostructure. So I looked up into another book in order to find other type of ...
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48 views

How big was the first transistor?

The first working point-contact transistor made in 1947 by Bell Labs. I'm looking for specific dimensions, all I've been able to find is "Fits in the palm of your hand".
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Semi-conductors

Suppose there is a semiconductor with Fermi energy $E_f$ and that there are $N$ bound electron states. I'd like to know why the mean number of excited electrons takes the form $$\bar n={N\over ...
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Why is titanium dioxide transparent for visible light but not for UV?

I wonder the reason for TiO2 thin films to be transparent for visible light but not for UV. I made a quick search and I found that it is due to the band gap of TiO2. It absorbs UV light but not ...
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If we connect a block of p-type semiconductor only to a positive terminal, will it become positively charged?

Connect the positive terminal of a battery to a piece of p-doped semiconductor, say, silicon doped with boron. Will the terminal pull electrons out of the doped silicon, or equivalently, inject holes ...
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Semiconductor problem: how much Boron is required to establish a certain amount of charge carrier density

The problem description is as follows: Boron is used to dope 1 kg of germanium (Ge). How much boron (B) is required to establish a charge carrier density of 3.091 x 10^17 / cm^3. One mole of ...
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Model for a thin metal/semiconductor junction?

Are there any books or articles that describe models for transport in a metal/semiconductor junction where the thickness of the semiconductor is less than the thickness of the depletion/accumulation ...
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Rms value of rectified output from a half wave rectifier

The rms value of an alternating quantity which is the input to a half wave rectifier is $\frac{I_{max}}{\sqrt2}$. Then the rms value of output should be $\frac{I_{max}}{2} \sqrt 2$. But it is given ...
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When recombination in PN junction occurs, which atom becomes an ion?

In an unbiased PN junction, when the carriers recombine to form a depletion layer , it is said that immobile ions are formed. We know that the conduction band electrons in N type are not associated ...
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72 views

Band gaps: are they at the centre or at the edge of the Brillouin zone?

Reading about electronic band structures, I came across the following: Band gaps open at the edges of the Brillouin zone (BZ), since that is where the Bragg scattering occurs. I am slightly ...
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65 views

How depletion region is developed in a Schottky diode?

In a P-N junction depletion region is developed when electrons from N-region diffuse to P-region and hole from P-region diffuse to N-region. Here diffusion thereby development of depletion is caused ...
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Light intensity (affected by semiconductor's absorption)

An experiment recently was done in order to measure the band gap of certain semiconductor. In order to gather the transmission coefficient for a spectrum of light, a light intensity of the system ...
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Conductivity of a crystalline solid

In a crystalline solid each atomic level 'splits' into n levels (n = number of atoms in the system). When the number of atoms is large each level becomes replaced by a band of closely spaced levels. ...
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Difference between steady state and equilibrium?

In semiconductor physics, what is the difference between steady state and equilibrium. How analysis of devices varies in these processes?
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How does band narrowing (heavily doping the emitter) affect the alpha F and alpha R in the Ebers-Moll model of a BJT?

I think that when the emitter is heavily doped, the bandgap is reduced which increases the reference forward current(current flowing through the E-B junction ) but the alphas themselves do not change. ...
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How do Zener diodes maintain the potential across their terminals?

My physics book has a topic about Zener diodes being used as voltage regulators in the reverse bias. Well, I'm curious to know how does a Zener diode maintain the potential across its terminals after ...
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What is the derivation of the formula for the probability of transmission through a barrier?

This site has a formula for the transmission probability over a barrier (in transistors): $$ T \propto \exp [-2(2m^*/\hbar ^2)^{1/2}(q\phi)^{1/2} d ]. $$ Where $T$ is the transmission probability ...
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Derivation of existence of energy band gap in semiconductor (solid State)

I am looking for both a mathematical and a physical reason for energy band gap in metals. For Physical reason, I was told that at each reciprocal lattice, you could have Bragg scattering, that would ...
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What can justify the decrease of the electrical conductivity with the increase of light intensity?

I have currently been working with a sample that "appears to" decrease its resistance when I cover it and protect it from light. Basically it presents the opposite behaviour of a photoresistor. What ...
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Basic concepts in quantum theory to start learning semiconductor physics [closed]

What basic concepts in quantum theory one must known to start learning semiconductor physics?
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Types of semiconductor relaxation

Ok, so you've basically got tensile and compression strain in a lattice mismatched material right? So as you're epitaxially layering the material, the strained material is deforming more and more ...
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What do I get when measuring on top of metal/insulator/metal by kelvin probe?

I am using a macroscopic Kelvin Probe for work function measurement. There's one confusing condition. If I measure a trilayer thin film stack with a structure of ITO(bottom)/PMMA(100-200nm)/Al(top), ...
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In solar cells, do photons break apart electron-hole pairs, or create them?

Some sources say that when a photon hits the PV cell, it breaks apart electron-hole pairs. Other sources say that photons create electron-hole pairs. Can anyone explain which one is right? I've read ...
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450 views

Turn-on delay time for Laser diode

Do you know any simple explanation on the reason why the turn-on delay time on a laser diode is reducing while we increase the bias current? Turn on delay,is the time that the laser needs from the ...
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Vacancy Generation / Annihilation Time (Relaxation Time)

Vacancy Generation/Annihilation Time, Recombination Time and Relaxation Time ($\tau$) are all synonymously used in atomic physics literatures. They're defined as the time that it takes for vacancies ...
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46 views

What is the speed of electrons in a transistor?

What is the average speed of an electron in a MOSFET transistor, and how can you calculate this? I've heard people throw terms such as "drift velocity" and "Fermi velocity" around, but I've never ...
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Why absence of electron is called hole?

I am having hard time in understanding the concept of holes: If there is no electron than how can it be a hole? For a moment lets assume absence of electron is termed as hole but how can this absent ...
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Why is more intrinsic carriers bad for high temperature semiconductors?

I'm taking a solid state course, and is currently on the subject of dielectrics. In one of the sections, concerning "Impurities in Dielectrics" the books says: "Impurities can also be used to make ...