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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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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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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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?
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Help with the analytical solution for the dispersion relation of an elastic wave with wave vector k

I was studying Phonons and Lattice vibrations and came across the equation. I want the mathematical solution for this. $$M\frac{d^2u_n}{dt^2}=C[u_{n+1}+u_{n-1}-2u_n]$$ from here it is argued that ...
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Why in excitation in indirect bandgap materials photon absorption is always before phonon absorption?

Why is it always photon->phonon? Why can't it be phonon->photon? (source)
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For an intrinsic semiconductor, why is fermi level half-way? [duplicate]

Why is the fermi level half-way between the conduction band and valence band?
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Relation between energy band gap and atomic number

Is there any relation between energy band gap in group4 elements and their atomic numbers? It might be just a trivial observation but I noticed How from Carbon to Germanium the band gap went from ...
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Are there electrons in the electron energy levels that are created due to doping in N type semiconductors?

I was going through this article.There it is mention that The addition of donor impurities contributes electron energy levels high in the semiconductor band gap so that electrons can be easily ...
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Can the Fermi energy lie into the band gap?

Fermi energy $\rightarrow$ highest energy level filled at $T=0K$ Fermi level $\rightarrow$ Energy level where we have a chance of $50\%$ to find an electron. Now in my course text they say that for ...
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How is a semiconductor electrically neutral?

I'm in the process of learning how transistors works, which starts with understanding how doping is used to create n-type and p-type semiconductor materials. All the resources I read sort of explain ...
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When doping a material, why is As called impurity?

Doping is the act of adding impurities to Group-IV elements to e.g. improve their conductivity. Though it is improving the conductivity, why is it called impurities?
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electric potential at the other end of diode

I was brushing my basics about diode & got stuck at a point...my question is Consider a diode let the positive terminal of the diode be connected to +ve of battery Now in the figure let the ...
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Semiconductors light emission

Suppose a pure semiconductor, with a direct gap. If I apply a constant voltage to it the electrons will jump to the conduction band. So when I turn it off will it emite light?, because the electrons ...
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Resistance & temperature of semiconductor

From what I have read about semiconductors, the reason their IV characteristic shows a decrease in resistance is because as voltage is increased, current is increased. However, the reason for the ...
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Do holes have physical existence?

We know that holes are created due to electrons hopping from one covalent bond to another. But does a hole have a physical existence or it's just a fictitious positive charge, an illusion created by ...
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Concentrations of carriers in semiconductor

For a given semiconductor at a given temperature $T$ with doping levels of acceptors $N_A$ and donors $N_D$ and intrinsic carrier concentration $n_i$ without any external biases, how can I calculate ...
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Combining a p and n type semiconductor

According to my textbook, when a p and n type semiconductor combine the following happens: Electrons from the n type semiconductor will migrate into the p-type semiconductor at the junction (so the ...
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How do the Fermi level, HOMO and LUMO change with doping?

I am a bit confused about solid state physics of organic materials because as I know the workfunction changes with the doping of a material but the Fermi level is constant with doping. So depend on ...
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Steady State Solution for Carrier Concentration of Intrinsic Silicon in an Electric Field

I'm trying to model carrier action in intrinsic silicon under an applied electric field in one dimension. Taking $n$ and $p$ to be the concentrations of electrons and holes respectively, I got that ...
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What's an intuitive understanding of diffusion capacitance?

Diffusion capacitance often comes up in transistor design. It is one of the two main capacitances you see, the other being the depletion layer capacitance. The depletion layer capacitance (per unit ...
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Diodes in AC current

If in AC current, the direction of the current is always changing, then if one was to place a diode (for simplicities sake lets say an LED) in an AC current, would it flash to the frequency of the ...
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Understanding electronic band structure diagrams

Currently I'm trying to understand electronic band structures such as depicted below: And following questions were arisen. Why are there multiple lines in valence side and conduction side? Where ...
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What is the connection between Bragg's condition with reduced EK diagram?

In my course notes the professor mentioned that there was some relationship between the Bragg's condition and the first Bernoulli zone of the reduced EK diagram. Specifically, the boundary before ...
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What determines the forward voltage drop for a diode?

I have always had the idea that the forward voltage drop in a semiconductor diode was related in a simple way to the bandgap energies in the semiconductor. However this is apparently not the case: ...
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How does annealing improves the ohmic contact?

Suppose we have a p-type material and metal contacts deposited taking the work function of a metal and semiconductor into account. At room temperature (depending on the doping level) they might now ...
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Tunnel diode/quantum tunneling

How does a tunnel diode work?/How does a tunnel diode use quantum tunneling, and how does quantum tunneling make the diode faster?
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Reverse Recovery Current of a diode

When the diode is in forward bias phase and suddenly we apply a reverse bias voltage, the diode takes time to be fully blocked because of the excess of minority charges that are stored in P and N ...
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Kirchoff's voltage law doesn't seem to hold in an experiment conducted with series resistor, diode and signal generator

I've conducted an experiment to look at the electronic characteristics of a diode. This was done using a series diode, resistor ($R$) and signal generator. The signal generator was made to supply a ...
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Shining light (of a particular frequency) on an insulator to make it into a conductor

Recently I read about band theory of solids. The energy difference between valence band and conduction band determines the conductive property of solids. Suppose I take an insulator and shine it with ...
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Do batteries provide electrons

In chemistry, the reaction at negative electrode produces electrons,which flow to the positive electrode through the circuit. But then, if circuit has a conductor, then wouldn't it also release ...
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Does the Fermi level change under change of temperature, voltage or other conditions?

From a previous post with similar title, (What's the difference between Fermi Energy and Fermi Level?) I think it is safe to assume that In a block of material, Fermi energy is the level, up to ...
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Optics - Photodiodes - minimum photon energy that a photodiode will be sensitive to [closed]

I'm foraying into the world of photodiodes, and I'm trying to calculate the minimum photon energy required for the photodiode to be sensitive to. Symbolic expressions desired. Minimum detectable ...
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Why is a substrate needed in growing GaN?

Is the substrate a layer on which GaN crystal grows on? Is there a way to grow free-standing GaN? Would the resultant crystal be full of defects?
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What is the relationship between Raman peaks and phonon vibration modes?

I've seen Raman spectra, such as here, where peaks at certain wavenumbers were identified with phonon vibration modes (TO, LO, TA, LA). What is the relationship behind this, and how could I make such ...
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When a pn junction is formed, why is a positive region of charge formed on the n side of the junction?

I understand that when electrons diffuse from n-side to p-side, negative charge is developed on the p-side. But the mere absence of electrons on the n-side doesn't make that positively charged. The ...
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Flaw in Einstein's explanation of the photoelectric effect?

The essence of Einstein's idea is like this: if a system is in some bound state with energy $-E_b$ with $E_b> 0$ (the threshold of the continuum band is taken as zero), and we drive the system ...
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The meaning of the temperature in the Shockley Equation

In the Shockley equation, which is the model of the $I$-$V$ curve of a p-n junction, what does the Temperature refer to, carrier temperature or lattice temperature? When a p-n junction subjected on a ...
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Relation between carrier temperature and lattice temperature, under injections

When we are learning the semiconductor physics, we always encounter a key concept, which is the carrier temperature. However, there is not any detailed definition of such carrier temperature. Do we ...
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Do electrons in the conduction band have a quantum number?

Sorry if this is a silly question, but I haven't seen the concept anywhere and was wondering why. If valence electrons can have a quantum number, why can't conduction electrons? Is there something ...
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Numerical Solution of 1D Boltzmann Transport Equation

I need to solve the one-dimensional Boltzmann transport equation in a semiconductor numerically, and I want to take a deterministic approach toward the problem (i.e. not use Monte-Carlo or similar ...
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Why do the free electrons in N-type want to diffuse?

I'm trying to understand how a diode works and for this I've used(among other resources) the book written by Albert Malvino, Electronic Principles. Everywhere I read about this topic, it says that ...
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Activation energy as a function of defects

Electrical conductivity has a form of Arrhenius equation. It is assumed that activation energy decreases with defect density in the insulating state and becomes zero in the conducting state. Can one ...
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Factors on which barrier potential in a p n junction depends

I have a few queries regarding the barrier potential in a p-n junction diode. Is the barrier potential dependent on temperature? Why/why not? Does the barrier potential depend on doping ...
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How holes conduct current?

I had questions about holes in semiconductor, when i checked the net it is said holes are said to be equivalent positive charge and they say because the hole moves from one place to another when it is ...
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What controls the on-off speed in a microprocessor? [closed]

I've been spending some time reading about semiconductors and even about computer architecture in order to understand how computers actually works in lowest levels, but until now nothing what I read ...
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How does the saturation current of a heterojunction depend on on the band gap difference?

In my textbook, they demonstrate that, for a regular n-Si/p-Si pn junction, the electron saturation current density (it's pretty much the same for the holes, but with hole properties instead of ...