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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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
53 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
79 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
67 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
131 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
108 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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40 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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1answer
102 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
24 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
34 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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0answers
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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0answers
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 ...
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2answers
153 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 ...
4
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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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109 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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0answers
39 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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0answers
13 views

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
55 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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0answers
39 views

Luminous Efficacy problem for LED. Semiconductor Physics [closed]

You have a white light LED with 100 lumens/W luminous efficacy when biased at 100 mA  and 0.8V.  Assume the diode has ideal characteristics and that luminous flux is linear with  diode current (a ...
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165 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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31 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 ...
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2answers
52 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
484 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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80 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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0answers
13 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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11 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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33 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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11 views

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 ...
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0answers
32 views

Resistance of a diode

A diode is represented by an EMF equal to the electric field in depletion zone plus a resistance. This resistance is obtained from the I/U characteristic of a diode. My question is, this resistance is ...
2
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1answer
54 views

Doped semiconductor: “what if all donated electrons are gone?”

I have trouble understanding conductivity of a n-doped semiconductor in the band theory. I know that donator atoms carry one excess electron that can enter the conduction band easily. If this ...
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2answers
99 views

White Laser Light

I have heard that recently researchers have developed white laser light by combining semiconductor laser sources of different colors. However, I have heard that before these lasers become a practical ...
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1answer
48 views

Why dopant energy levels differ from one material to another?

Dopant levels in Si, Ge and GaAs are very different from each other. Even "similar" materials such as Si and Ge exhibit different dopant energy levels. (source: Pierret, Advanced Semiconductor ...
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1answer
51 views

Depletion region (PN Junction) question

So I understand P and N type semiconductors and the depletion region makes sense. http://hyperphysics.phy-astr.gsu.edu/hbase/solids/pnjun.html (using this as reference for my question). So the ...
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0answers
15 views

What is the use of diode? [closed]

I am confused about the use of diode. As I am look into the use of diode in Wiki, it mentioned one of its use is to be a component of rectification circuit. But will it cause damages to the diodes if ...
0
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1answer
65 views

p-n diode, Power as a function of the logarithm of the circuit resistance

in a circuit comprised of p-n diode and with characteristic Ohmic resistance making the diode's resistance negligible , we have for the current passing through the diode $I=I_s(exp(Ve/kT)-1)$ where ...
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1answer
42 views

Why Solid Insulators have highest breakdown voltage?

Why does solid insulating materials have a higher breakdown voltage when compared to that of liquids and gases? Can anyone explain this in simple words?
2
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0answers
80 views

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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0answers
58 views

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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23 views

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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1answer
30 views

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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0answers
46 views

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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73 views

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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1answer
54 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 ...