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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What happens after an electron and hole combine?

OK so I understand that an LED is a pn junction where when a forward bias is placed across the junction, the electric field causes the electrons to combine with the holes and release a photon through ...
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47 views

Electron jump into a transistor to read qubit state

Prof. Andrea Morello, a quantum physicist, in one of its quantum computer models uses the spin of the outermost electron in a phosphorus atom to represent a qubit. This atom is embedded to a ...
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1answer
62 views

Liquid conductors and conservation [closed]

Would gas or liquid conductors cost less than metal and are they more efficient conductor? Is there a material that would contain a magnetic field and would it increase conductivity? If so, This ...
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2answers
85 views

What is the meaning of the zero point of the real part of the dielectric function for a semiconductor?

I basically understand the zero point of the real part of the dielectric function for a metal. It generally corresponds to plasmon. For a metal, if the frequency is lower, the real part is negative ...
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1answer
50 views

P-type semi-conductor: Hole current VS Electron current

In a p-type semiconductor, it is said that the hole current is greater than the electron current, which makes no sense to me.. The hole current is due to the electron current, right? Electrons jump ...
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14 views

Calculating the band profile of a complex semiconductor heterostructure

I am an EE undergraduate with a lot of interest in semiconductors. I took an introductory semiconductors course which was helpful but left me with some holes in my understanding, as the course ...
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15 views

Are diodes (or FETs) electrets?

The explanations I see of diodes and FETs seem to involve various depletion regions, migration of electrons and holes, and the such. My (perhaps naive) interpretation of these explanations implies ...
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16 views

the Fermi level of MOS capacitor

Consider a p type MOS capacitor. As we tune the bias of the device, the fermi level of the body would change. Why do the difference of the fermi level between gate and body is equivalent to gate ...
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1answer
184 views

Density of states for graphene

I have seen a lot of plots for the density of states for graphene: but have been unable to find the calculation explicetely. I know the dispersion relation for graphene is $E_{\pm} (\textbf{k}) ...
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19 views

Conductive n-type material in pn junction

I'm interested in this question from the point of view of a solar cell. In a pn junction (example, p: CIGS, n: CdS), when the n-type material is very conductive, why will the junction not be ...
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29 views

Why for each electron – hole recombination, an electron from the negative terminal of the battery is released

Why for each electron – hole recombination, an electron from the negative terminal of the battery enters the N-region and then drifts towards the junction?
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23 views

Intersection of $\rho_{xx}$ and $\rho_{xy}$ in Drude magnetotransport

Okay, so I've recently been working through the rather elementary derivation of the Hall effect in a 2 dimensional electron gas, using the Drude model. The idea is that with an E field in the x ...
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10 views

Differences between Metal-Bridge-Metal system and Donor-Bridge-Acceptor system

What is the real difference between Metal-Bridge-Metal system and Donor-Bridge-Acceptor system? In MBM there are anchor groups between the molecule and the metal electrode, can’t the groups act as ...
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1answer
46 views

What causes depletion layer to form?

I am trying to understand why and how a depletion layer forms between a P type and N type semiconductor. Before putting into contact a P type and N type semiconductor, both are electrically neutral. ...
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51 views

Van der pauw method for an isolated hole

Van der pauw method is a way to measure the resistivity of a material with arbitrary shape while it meets some specifications ( being homogeneous and ...). One of the conditions is that the sample ...
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33 views

Selection rules in a finite quantum well

I have a finite quantum well made of two different semiconductors with different bandgaps and I want to calculate the different transitions between the energy levels possible that I calculated in that ...
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1answer
606 views

How is a CCD able to collect images in drastically different lighting conditions?

I have read the basics of how a digital camera works. As much as I have understood, the digital cameras have a device called a CCD on which photons coming from the lens are incident. The CCD then ...
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3answers
62 views

Why are holes in p-type semiconductors considered positively charged?

This makes no sense to me and i think it's more of a convention. Even though we prefer talking about holes that are the majority carriers in p-type semiconductors, they have no charge and are not ...
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1answer
99 views

How to use Anderson's rule to construct band discontinuities in heterojunctions

I'm having some trouble in applying Anderson's rule to get a crude approximation for the band diagram of heterostructures. To make it more specific, I'm considering a donor-doped AlGaAs layer on top ...
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2answers
89 views

How do we get a 2DEG in a remote doped heterostructure?

I have a question regarding the way in which one often constructs a two-dimensional electron gas in heterostructures. I have a specific example in mind, although I believe this is quite a common way ...
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1answer
42 views

Where does the lowered effective mass of electrons come from?

It is a known fact that electrons in the conduction band of a semiconductor can (in certain scenario's) be described as having an approximate parabolic dispersion relation of the form $E_c(k) = E_c + ...
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1answer
236 views

Why do we have heavy and light hole bands in semiconductors?

On the topic of the valence band of a semiconductor (in this example GaAS), it is the case that the valence band has some structure to it. As shown in the illustration below, we see that at the ...
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1answer
136 views

Why are holes the majority carrier in P-Type semiconductor?

It is said that P-Type semiconductors' majority carriers are holes. But based on my current understanding, there should be no extra holes except for those generated by heat (i.e. electron-hole pairs ...
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42 views

Diode's volt-ampere characteristics

The Problem is that If the reverse saturation current is $10\ \text{nA}$ ($1\ \text{nA}=10^{-9}\ \text{A}$), Calculate the forward current while the forward voltage is $0.6\ \text{V}$. And explain ...
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115 views

Analogy in combination of batteries in series and pn junction diode circuit to find potential difference

Can I use the analogy of combination of two batteries to get the potential difference between two points(by applying Kirchhoff's law) in case ,if a pn junction diode is used in the place of other ...
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2answers
35 views

Semi conductors (holes and electrons)

The following relation is mentioned in my text book for semiconductors in thermal equilibrium. $$n_e ×n_h = n_i^2$$ $n_e$ stands for the number of electrons. $n_h$ stands for the number of holes. ...
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1answer
26 views

Does drift current eventually stop in a p-n junction?

According to the Wikipedia's graph of electric field in a p-n junction, there is no electric field outside the deletion region and hence no minority charge carriers move into the other side. Also, the ...
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1answer
36 views

What does it mean that an electron-hole pair is the fundamental unit of generation?

I wasn't certain to post this in chemistry or physics section. I was reading the wikipedia article on "Carrier generation and recombination" and in the second paragraph it says something that I ...
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22 views

How do electrons move across depletion region in npn transistor? [duplicate]

Concerning the base-collector barrier, the electrons coming from the emitter move through the barrier using diffusion mainly and drift. Does carrier injection happen as a result of these two ...
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29 views

Cookbook recommendation for finite element semiconductor simulation possibly using Sentaurus

I've started work for my master's thesis using Synopsys Sentaurus for simulation of semiconductors. I'm interested in the device simulation, that is the physics, not the process simulations. The ...
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9 views

Simulate Band Bending and Band Alignment in Semiconductors

Are there softwares (simple ones preferred) where we can simulate the band alignments and band bending of a p-n junction, where we can vary properties of the junction materials such as carrier ...
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15 views

semiconductors-band theory [duplicate]

How conduction happens with the conduction band electrons? I mean does the electrons which are responsible for the conduction of holes(by just moving from one atom to other) are those which are ...
5
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2answers
184 views

Why are only Group III & V elements used for doping?

Only group III & IV are used for doping in elemental semiconductors like Si and Ge, why can't other groups be used instead?
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1answer
54 views

What are the current carriers in a PN junction?

Imagine a PN junction in forward bias mode. The conventional current goes from the p-side to the n-side. However, as mobile holes move to the n-side, aren't there mobile electrons on the n-side which ...
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1answer
110 views

Electron with position-dependent effective mass in magnetic field - non Hermitian Hamiltonian?

In semiconductor heterostructures it is important to treat the case of position-dependent effective mass. The (mostly) accepted form of kinetic energy operator in this case is: $$ \hat{T}=- ...
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1answer
47 views

Bandgaps of Silicon and their application in active optical elements

I know that silion has an indirect bandgap at $E = 1.12 \, eV $ or $ \lambda = 1.107 \, \mu m$ and I have read that active optical processes like absorption and emission have a decreased likelihood to ...
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112 views

what is the theoretical reason behind the new paper, Highly tunable hybrid metamaterials employing split-ring resonators built using graphene?

A few days ago, a group of University of Exeter physicists published a paper titled: Highly tunable hybrid metamaterials employing split-ring resonators strongly coupled to graphene surface ...
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40 views

Two-Band k.p Model is not Hermitian for imaginary wavevectors

In E. O. Kane's original work on Zener Tunneling, he uses a two-band $k\cdot p$ model for the semiconductor bandstructure: ...
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What do you actually mean by DC current gain and a AC current gain in transistors [duplicate]

What do you actually mean by DC current again and AC current gain? I know there for formulas but I did not understand what actually they are , what is the significance. So basically I do not ...
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1answer
60 views

Why does small change in Base current causes a larger change in collector current in case of transistors? [closed]

Why does small change in the base current causes larger change in the collector current. That is say if I increase the base current buy a small amount why the collector current increases by a very ...
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201 views

Exact (quantitative) definition of “knee” and/or “cut-in” voltage?

Sort of a 2-part question: 1) I know they are used interchangeably but are the "knee" and "cut-in" voltages of a diode actually the exact same thing? I had thought that the "cut-in" voltage was ...
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33 views

How to escape freeze-out effects of semiconductors in very low temperature

In very low temperature, semiconductors suffer from freeze-out effects. I did see that degenerately doping eliminates freeze-out, but degenerate semiconductors behave like metals. Is/can there ...
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0answers
18 views

Do equalized Fermi Levels imply zero concentration gradient?

The explanation of a P-N junction says that the Built in Voltage opposes the continual diffusion current leading to a net current of 0. What i don't understand is how there can be continual ...
0
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2answers
55 views

Why do we need Diffusion currents to explain semiconductor current flow?

Why do we need the idea of carrier concentrations to explain current flow? Can we simply not associate the disparity in carrier concentrations between two samples to a disparity in relative charge ...
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1answer
485 views

Why is photodiode made reverse biased?

If only its purpose is to create an additional electron-hole pair,then why would it be made reverse biased.We can good amount of current in forward biased condition.
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105 views

Zero Hall coefficient for semiconductors

Is it possible to dope the semiconductors in a way that their hall coefficient is zero?
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15 views

Hall coefficient for semiconductors

I read somewhere that hall coefficient for intrinsic semiconductors is zero. But how is that possible because the mobiliities of holes and electrons are never the same?
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12 views

Is it possible to select a single carrier type in a photodiode?

I have been reading about avalanche photodiodes and understand that they work via the impact ionization process to produce internal gain in the diode before the signal is read. It appears that ...
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1answer
34 views

Is Zener Breakdown a special case of Avalanche breakdown?

I was wondering if Zener Breakdown is a special case of Avalanche Breakdown which just works at a lower potential due to heavy doping.
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Is it posssible to numerically simulate a metal layer the same way as a semiconductor one

I need to simulate a schottky junction device. Unfortunately, the software for simulation (AFORS-HET) doesn't allow adding metal (I need to simulate aluminum contact) layers (but it allows to add ...