Questions tagged [semiconductor-physics]

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 can one determine the key characteristics of a solar cell from the I-V curve?

I have recently measured the IV characteristics of several Si solar cell samples and am now attempting to extract the series resistance $R_S$; parallel resistance $R_P$; open circuit voltage $V_{OC}$; ...
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220 views

Temperature influence on Hall Effect for semiconductor

Currently, I'm taking a course in modern physics experiments and last week I was asked to study the hall effect in a semiconductor. One of the experiments was with a germanium chip where a steady ...
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Is activation voltage the sum of voltage required to collapse depletion layer and band gap energy?

Is the energy released when an electron moves from the valence to conductance band states the activation voltage or is activation voltage the energy required for electrons to overcome the depletion ...
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61 views

How do electrons exit LEDs? Aren't they in the valence energy state?

If a conducting electron reduces to the valence band in an LED, where does it get the energy to go back to the conductance band upon leaving the diode so current can flow? I'm confused as to how ...
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61 views

Why n and p are not additive in law of mass action? or Why is the sum of electron concentration and hole concentration is not constant?

I was asked this question during a viva examination. I tried to give answer through mathematical derivation but I was told to give the answer from intuition. So why is $n_0 p_0 = n_i^2$, and not $n_0 ...
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Simulation of QW gain

For a student project, I need to compute and plot the gain of a semiconductor quantum-well. In my case, I am interested to reproduce the results from Schwartz et al. (Investigation and comparison of ...
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30 views

Half-wave rectifier output graph

I want to know what will be the output V-t graph when you connect a half-wave rectifier to a battery using an inverter instead of a traditional AC source? Because when I tried it, the output graph ...
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41 views

Electronics and junctions

In a p-n junction, is it only the electrons that move from the n-type part to the p-type part in order to create a depletion region or is it the movement of both electrons and holes from the n-type ...
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21 views

Which statistical distribution could be assumed for the mobility of Silicon substrate material?

Mobility is a key parameter for Hall elements or in transistor models. If we measure the mobility on Si wafers, then we can expect some variation from die to die or sample to sample. Which statistical ...
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65 views

At null temperature (0 Kelvin), is the current going through a diode (PN junction) null?

At null temperature (0 Kelvin), is the current going through a diode (PN junction) is null, for a positive voltage in a direct polarisation, above the built-in voltage of the depleted region ? If ...
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Would a block of doped semiconductor connected to a metal wire gain electric charge?

Consider a block of negatively doped semiconductor connected to a large section of metal wire. (I am assuming a negatively doped semiconductor for specificity, while implying a similar, though ...
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Is the current flowing through a zener diode in forward bias greater than the current flowing through an ordinary pn junction diode in forward bias?

Does current flowing through a zener diode, when forward biased, increase due to heavy doping?
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Reverse bias voltage drop

In reverse bias , when we go up the breakdown voltage why is there a voltage drop across the diode?.I mean the diode does resist to the flow of charges but when the electrons flow inside the diode ...
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Diodes normal polarised with voltage below forward voltage

Assume we have a circuit with a diode and a voltage source . The voltage source has potential 0.4V .If we polarise forward the diode ( p type region connected to cathode and n type region connected to ...
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Reverse breakdown

What happens to a PN junction after the biasing voltage reaches the reverse breakdown voltage ?That is what exactly happens to that immobile majority charge Carriers ?Do they also contribute to the ...
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46 views

Diffusion current and depletion region with doping

I've been told that depletion region width decreases when we increase doping in a P-N junction. But doesn't this contradicts the fact that diffusion current increases with current? I'm probably mixing ...
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25 views

Drude model for diodes

Well I was wondering how we can apply the drude model for diodes.The normal drude model is used on conductors and insulators and since the diode in forward bias is a good conductor(not the best but no ...
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Low energy electrons occupy holes

In Tipler's Physics it is said that for a temperature $T>0$ the only electrons that can gain energy from collisions are the ones with initial energy greater than $E_F-K_BT$. I understand that, ...
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597 views

How can electrons travel from the valence band into the conduction band?

I'm currently studying Introductory Semiconductor Device Physics by Parker. In band-theory, we know that if an electron is at the top of an energy band, then there are no allowed states immediately ...
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23 views

Why don't electrons build up opposite electric field in a semiconductor diode in open switch mode?

I understand that during the closed switch mode the opposite electric field gets wider, but i don't see the reason when in open switch mode when electrons beat the opposite p-n field (0,3-0,8 volts), ...
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Why Li is not added as contact by ion implantation method in p type HPGe detector? [duplicate]

n+ contact of p type Ge is ~700µm thick compared to p+ contact of n type Ge only ~0.3µm. The process of adding the contact is different. n+ contact Li is added by diffusion process but p+ contact B is ...
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Why does the space charge in the depletion region in a pn-junction not create an electric field in the neutral region?

The majority carrier conduction electrons in the n-region of a pn-junction are closer to the the positively charged donor ions than the negatively charged acceptor ions in the p-region. The situation ...
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What is the density of states $SiO_2$?

We build the model by the finite element method. In our model here is silicon dioxide (SiO2). To carry out calculations, it is necessary to know the density of states and the effective mass. Question:...
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Why and how do holes in the valence band of the p-type material of a p-n junction diffuse through to the valence band of the n-type material

tl;dr -- See the question title I quote from this Wikipedia article on the depletion region: By definition, the N-type semiconductor has an excess of free electrons (in the conduction band) ...
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Can I consider electron scattering with grain boundaries in metal as a tunneling process?

I am reading about the Mayadas-Shatzkes model (MS model). when electrons are scattered with the grain boundary, there is a probability that it will be transmitted to the other side of the grain ...
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Electric fields and electric potentials in semiconductors

The zener diode is heavilier doped than a normal diode , that is why its depletion region is smaller than the delpetion region of a normal diode and that is why the electric field is very strong.Zener ...
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Why does the p-region have a higher energy level than the n-region in a diode?

Looking at the image below, I'm curious as to why the p-type region is at a higher energy level than the n-type region when no external voltage is applied. How is that? The E-field, if I'm not ...
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Zener diode electric field working principle

Well I recently saw a video from khan academy about zener diodes.This video was suggested by another member of Stack Exchange Physics who I thank him very much . But I didnt understand some things:...
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111 views

Semiconductor and Fermi level in semiconductor

According to band theory, at $T=0\ \text{K}$ the Fermi level of an intrinsic semiconductor lies in between the valence band and the conduction band, while in the case of an insulator it lies near the ...
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100 views

Types of effective masses

I understand the existence of effective mass for electrons, light hole, heavy hole, and split-off. But how can they be different from the density of states effective mass of conduction and valence ...
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Gamma spectrometry: effect on one peak when adding another source

Suppose I have a sample containing only 137Cs. Now assume it shows 1000 cps counts for 137Cs, 662keV energy. Now I added 60Co (1173, 1332 keV) source in the same sample. Compton scattering ...
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Questions regarding germanium detector

Why n+ contact in n type Ge is not several hundred microns? . Why we require both additional p or n type contact? in p type Ge, why we require additional p type junction also? crystal itself should ...
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NPN transistors reverse biased

How is a pn reverse bias junction is formed in a NPN transistor? In a normal pn diode during a reverse bias junction an 'internal battery ' is formed which counteracts the movement of electrons . But ...
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What is a “space-charge”, in the context of photodetector non-linearities?

I'm going back and reading all these papers from a few decades ago regarding detector nonlinearities, and they talk a lot about space-charges and the space-charge field, but not one paper I've found ...
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Diffusion stopping current?

In the forward bias when electrons enter the p-type region of the semiconductor, the charge concentration is increased, and since the movement of electrons is faster than the movement of holes, it ...
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99 views

Relation between intrinsic Fermi level and electric field

If I consider a semiconductor in equilibrium (type P or N, non uniformly doped, 1D situation), how can I express the electric field in terms of the intrinsic Fermi level? I am trying to approach this ...
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79 views

Working of a photodiode

I am reading photo diode and I have couple of questions in. So my understanding of a photodiode is that these are devices which consume electricity and produce light So if that being the case, I am ...
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34 views

Is it possible for the charge carrier concentration to go down when doping?

Not sure if this makes sense, but if a p-type material is doped with another p-type material, is it possible for the hole concentration to go down, or will it always increase?
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129 views

Is there a simple rule connecting all indirect semiconductors band gaps to their electron-hole pair generation average energy?

The band gap of Diamond, Silicon and Germanium is 5.5, 1.12, 0.66 eV while the average energy to produce an electron-hole pair for the same semiconductor is namely 13, 3.6 and 2.9 eV. This ratios are ...
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29 views

Width of depletion region in P-N junction [duplicate]

Hello I wanted to ask how the width of the depletion region in reverse biased condition changes with the external voltage source
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101 views

Reversed biased condition np junction

Well there are a few posts about the reverse biased condition but I have a problem understanding one thing. Why doesn't current flow in reverse biased diode? It the picture there are positive ...
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35 views

Is metallic hydrogen an example of exciton?

I know that in exciton an electron is excited and goes from valence band to conducting band leaving an electron hole which is positively charged, soon Jupiter came into my mind and then this question. ...
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58 views

leakage current as a function of the depletion width

How does the leakage current behave with an increasing reverse voltage applied to a semiconductor? Will it increase too or is it independent from the depletion with respectively voltage? I can argue ...
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184 views

What is the binding energy between conduction band and valence band of metals and insulators?

As far as my understanding of solid state physics goes, I can't see a clear connection between binding energy and band gap. But our teacher asked us the question as an assignment but i really can't ...
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476 views

Can a semiconductor become more conductive than a conductor with heat?

I am looking for a good idea for a science fair project for PA Junior Academy of Science (PJAS). An interesting idea that I have stumbled across is making semiconductors more conductive with heat. I ...
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54 views

Is the band theory valid for an electron with energy greater than the potential?

Consider Kroenig Penney model. Here there is a derivation that uses the following potential: One of the assumption is that the energy of the electron is $E<U_0$. Under this assumption (and others) ...
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Why are the electrodes in thermodynamic equilibrium for a working solar cell?

I was reading a paper that performed simulation of a solar cell under illuminated conditions. Obviously, in these conditions, the device is out of thermodynamic equilibrium. For example the ...
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Change the depletion width in the presence of light in a photodiode

In my simulations, in the presence of light, the depletion width of the layer decreases. Can light change the depletion width of the photodiode?
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Semiconductor Quantum Dots

Can someone recommend some good books on semiconductor quantum dots(InGaAs, GaAs etc..) from the perspective of a beginner student. I mostly want to learn about the optical states(the ...