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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Distance $E_F-E_i$ in a compensated semiconductor

Given two energy level diagrams for a compensated conductor: At $0~\text{K}$ At $500~\text{K}$ I want do determine for which diagram is the Fermi level closest/farthest from $E_i$. It's a ...
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applied voltage on n-typed semiconductor changes its carrier lifetime

An apparatus was constructed in the lab to measure charge carrier lifetime. An LED illuminates an n-typed germanium semi-conductor with a square function with a constant frequency (the period of the ...
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Hall coefficient '$R_H$' for intrinsic semiconductor

The Hall coefficient of an intrinsic semiconductor is: A) Positive B) Negative C) Zero D) Infinite ? What will be the best answer for this question? According to me It should be very ...
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MOS Capacitance variation with Voltage [on hold]

Can anyone indicate me about the details of MOS static capacitance variation with applied Vgb (gate to substrate voltage)? what I found in the literature is (afraid not) dynamic capacitance in ...
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1answer
21 views

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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55 views

How is quantum physics translated into the world of electronics? [on hold]

I remember watching a documentary about early works in quantum physics and how it was essential to the microelectronics revolution and the invention of the transistor. What part exactly helped? Is ...
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1answer
27 views

Does semiconductor laser need stimulating photon to produce coherent light?

In regular laser, we need: stimulating photon => this makes the output light coherent ways to make inversion population resonant cavity in the pictures about semiconductor laser, I do not see any ...
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13 views

Fano factor measurements

I am looking for information on the measurements of the Fano factor, in particular in germanium. Does anyone know accessible papers?
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What happens when electron keeps hitting on a metal plate

In SEM, in order to 'focus' the electron beam, an aperture is used (which usually is metal); what happens to the metal after so many electron hits the metal constantly? since metals are usually are ...
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Fermi level in metals and semicoductors

As we read about Fermi energy, it is the energy of the highest occupied electrons. But if we look at the energy level diagram of semiconductor the Fermi level is situated somewhere between the valence ...
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1answer
27 views

The n-type dopant elements on silicon

The n-type dopant elements on silicon are phosphorus, arsenic, and antimony from the group V elements. My question is that what is the difference between doping P, As, or Sb? How do we decide to dope ...
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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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1answer
23 views

How does one obtain a semiconductor's absorption coefficient from first principles?

Is the absorption coefficient of a semiconducting material at a given wavelength obtainable from the material's band structure? If so, how? Are there any pedagogical papers you could recommend to help ...
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Conceptual question regarding transistor biasing

I know that in a transistor, the base-emitter (B-E) junction has to be forward biased while collector-base (C-B) junction needs to be in reverse bias. Question: What would happen if we alter this ...
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Half wave rectifier confusion

I am searching for a good book or link or video that might give some fresh idea about half wave rectifier properties I mean in my book prescribe by my university that has introduced some of the basic ...
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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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47 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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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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Electrical properties of the Wannier exciton

We know that excitons are charge neutral and doesn't show any electrical properties, but is it the same for Wannier exciton too? For example, if a Wannier exciton placed in the electric field, can it ...
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35 views

Why there is no reabsorption in LED crystals?

Can you explain to me please, why there is no reabsorption in crystals which are used as LEDs? Because the energy of emitted light is the same as the band gap of the semiconductor - it should be ...
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1answer
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Question about the purpose of a transistor [closed]

I've been studying about diodes and transistors and something made me wonder about the purpose of transistors. In the examples we were talking about increasing current by using two batteries with a ...
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21 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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Semiconductor and temperature dependence

Does the conductivity of both intrinsic and extrinsic semiconductor increases with temperature or is it that conductivity of extrinsic semiconductor decreases with temperature just like a conductor ?
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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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68 views

How insulators and conductors were discovered?

I know Stephen gray has discovered insulator and conductor. But I want to know that how did he know which one is conductor and which one is insulator ? Please tell me the details how had he done that ...
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Why does the base-emitter voltage in NPN transistor become constant

The setup above shows the experiment that I have been working with. During the experiment, the current $i_c$ and the voltage $V_{be}$ were measured for increasing $V_{in}$. At some point, the current ...
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Resource recommendation for spintronics

What are some good beginner level books to understand spintronics. I am looking for some sources in which basic mathematics of spintronics is properly explained.
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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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1answer
102 views

Is this photodiode-based “energy harvester using the coldness of outer space” just based on established thermoelectric effects?

I've read through the explanation and can not understand what they are saying in terms of the underlying physics. My hunch is that this is a demonstration of a well established thermoelectric effect ...
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16 views

What is the definition of a bipolaron and a dipolaron?

I wondered about the exact definition of a bipolaron? In particular, if I have an oxygen vacancy in a metal oxide and the 2 excess electrons (when forming a neutral oxygen vacancy) localise on the 2 ...
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Upper State Lifetime vs Exited State Lifetime vs Gain Recovery Time

Could any one explain differences between these three terms about semiconductors and semiconductor optical amplifiers.
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Density of states in 1D semiconductor

I'm given the dispersion relation for the energy band of my semiconductor: $E(k)=\alpha+\beta\cos(ka)$ where $a, \alpha, \beta$ are know parameters and I must obtain the density of states from that. ...
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40 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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174 views

Where does the labelling of extrinsic semiconductors as “n” and “p” come from?

The naming of doped semiconductors as "n-type" (for donor-doped) and "p-type" (for acceptor-doped) is ubiquitous. But I am having a hard time digging up where this naming tradition comes from and how ...
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How to calculate energy of conduction band - fermi energy (Ec-Ef) - semiconductor

I am learning shottky diodes and i want to work out the built in potential barrier using: $$V_{bi} = \phi_m - [E_c - E_f] $$ now i come across 2 equations when working out Ec-Ef. the first: $$E_c -...
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51 views

How does the $I$-$V$ curve for bulk metal look like?

For semiconductors, the current (I) vs. voltage (V) relationship is as shown in the picture below. As we increase the applied voltage, the electron-hole pairs generate increases too, so we see an ...
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Reverse bias under 0.7V

Assume we have a diode. Well, I was wondering what is happening if we connect the negative terminal of the battery to the p type region and the positive terminal of the n type region to the positive ...
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1answer
27 views

MOSFET Body terminal

What is the point of the body terminal in a MOSFET. If we assume Vsoure=0, Vdrain>0 then we will have a linearly changing voltage from drain to source. Then if Vgate>0 , depending on the difference ...
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22 views

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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15 views

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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Why does applying a voltage through the gate on a transistor help lower the potential barrier?

At the potential barrier, all that atoms are "satisfied"; they each have the appropriate number of electrons in their valence shell since the free electrons on the n-type side fill the holes on the p-...
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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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23 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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Metal Oxide Semiconductor (MOS) Capacitor strong inversion

Why the electron bands in the Body of the MOS capacitor do not bend much futher after the threshold voltage is applied? What stops them from doing it? For reference Modern Semiconductor Devices for IC ...
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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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264 views

The difference between optical phonons and acoustic phonons in terms of energy absorption

Why can the energy of a photon be directly absorbed by an optical phonon but not by an acoustic phonon?
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How do you calculate the electric field from conduction and/or valence band energy?

I am currently using a program to calculate the band diagram of a semiconductor structure in 3D. I am wondering if its possible to use the finite difference method to calculate the electric field. ...