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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Diode as a voltage source [on hold]

We have known that diodes cannot be used as a voltage source. Eventhough is has a constant barrier potential depending on material used. Why can't we use an unbiased diode as a voltage source?
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Flattened band in band structure

What does a flattened band in a band structure plot imply? I've been reading this paper https://doi.org/10.1016/j.apsusc.2012.06.092 and one of the primary results is the flattening of bands however ...
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Fermi level and chemical potential in doped and pure semiconductors

Recently I was studying about band theory of semiconductors and I have some questions. I found two definitions of Fermi level $1)$ The quantum state which has a probability of occupancy of $0.5$ (...
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Surface States and Fermi Level

In work Gelmont, B. L., Shur, M., & Stroscio, M. (1995). Polar optical-phonon scattering in three- and two-dimensional electron gases. Journal of Applied Physics, 77(2), 657–660 when author moving ...
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If the current entering a charge preamplifier is a positive pulse, could the output voltage really be a positive pulse?

In this web page: http://physicsopenlab.org/2017/09/27/charge-sensitive-preamplifier/ they show the input voltage to a preamplifier and the output voltage. If I do the quick computation (see below), ...
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19 views

Ions in p or n -type semiconductor

I learned that in a p type semiconductor there are impurities with holes and the holes are majority carriers . What is puzzled me is the reason of appearing diffusion current actually . I've read this ...
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Why should the resolution of photolithography follow the pattern described in moore's law? [closed]

"Moore's law is the observation that the number of transistors in a dense integrated circuit doubles about every two years." The law basically limits the improvement in the resolution of ...
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24 views

At null temperature, why an electric field would not allow an electron from the valence band to go in the conduction band?

With thermic energy (increasing the temperature), the electron can move from the valence band to the conduction band. With another source of energy, as the energy from a static electric field, why ...
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Hall effect experiment- temperature variation

Why does the hall coefficient decrease with the increase in temperature? And becomes -ve for a p-type semiconductor after some significant temperature?
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In N-type sc at room temperature how does phosphorus becomes ion, after donating electron if it still has its octet complete with sillicon atom

We know that once octet is complete, an element becomes stable. So in this case if phosphorus has complete octet by sharing electrons with silicon by covalent bond, then how it becomes positive ion ...
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What is the influence of long excitation pulses on the relationship between luminescence intensity and the excitation intensity (Bimolecular process)?

In the luminescence processes (Bimolecular process), if long excitation pulses were used, and after a transient initial increase in luminescence intensity, i(t), the steady-state value of intensity is ...
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The polarization filter does not work

I am working in Conduction phenomena Photo-conductivity Experiment. Here the experiment guide . The aim is to measure the photocurrent $I_{Ph}$ as a function of the voltage $U$ at a constant ...
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Energy Band diagram in a exponentially $n$-doped Semiconductor and Space charge neutrality

The doping of an $n$-type semiconductor varies as $N_0\cdot e^{(-x/L)}.$ Find the electric field in equilibrium. Plot the band diagram. Comment on space charge neutrality. I got the idea that in ...
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Window comparator [migrated]

What happens if we reverse the configuration of diode in window comparator? will it remain a window comparator?
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79 views

Is it really true that valence band is completely filled at null temperature?

Is it really true that valence band is completely filled at null temperature ? Indeed, I would think that if we apply an electric field, this would give some energy to the electrons from the valence ...
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28 views

Difference between electrical conductivity and optical conductivity

Is there any difference between electrical conductivity and optical conductivity? How to explain it physically and is there any method available to connect them mathematically? If I calculate carrier ...
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Is diffusion of electrons (under Fick law) from N to P side of a PN junction dominated by electrons coming from doped or from non doped atoms ? Why?

Let's consider a PN junction between two semiconductor doped P and N. Let's concentrate on the N side for example. Due to Fick law, the electrons from the N side migrate to the P side. What is the ...
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How to convert $\rm{Mn_2O_3}$ to $\rm Mn_3O_4$? [migrated]

I was preparing $\rm Mn_3O_4$ but it was when characterized by XRD, a $\rm Mn_2O_3$ phase existed. Now how can I convert $\rm Mn_2O_3$ to $\rm Mn_3O_4$?
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Contact potential between metals

Metals Al and Au are connected in series. An ideal voltmeter, with both of its leads made of Cu, is connected across them. Then how come the voltmeter gives zero reading but why can't we measure ...
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22 views

In a PN junction formed from two semiconductors, is the depleted region made of ions only, or also made from neutral atoms?

Is the depleted region made only from ions coming from the doping of the semiconductor, or also from the atoms that have not been doped ? Are there non ionized atoms in the depleted region ? Do all ...
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In a semiconductor, why does the ionization create an electron/hole pair instead of an electron/ion pair?

In a gaz, the ionisation creates pairs of electron and ion. Why in the semiconductor, during an ionisation, there is no creation of an electron and an ion ? Thank you
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Why isn't nitrogen a n-type dopant?

n-type dopants are ones that have 5 valence electrons, so theoretically any of the electrons that are in that column on the periodic table should be able to increase the electron carriers in a semi-...
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Solar cell short circuit current

In order to obtain a solution to the short circuit current in a solar cell a boundary condition n=p=0 at the junction is imposed. Why only for short circuit current?
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Why carriers are free to move from dopant ions?

I apologise in advance for not finding the answer myself. I spent some time googling, but was only able to find a few related questions but no direct answer to my one. I also have to add that I'm not ...
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Hydraulic analogy for electrical compounds

I want a source (website or a book) where there are hydraulic simulation (or analogy) for all (or at least the most useful) electronic compounds?
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Saturation current in diode

I don't quite get why there should be a saturation current in a PN junction diode in reverse bias. The electrons in the N side should be pulled toward the battery, and the battery allows electrons ...
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Finding the Injection Efficiency and IV Characteristics of an LED

I have taken IV measurements for several LEDs and now need to calculate their injection efficiencies. I understand that the injection efficiency: $\eta_{pn} = I_{D}/I$ Where $I$ is the total ...
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I have calculated Crystalite size and it ranges 4 to 7 Aangstron. is it lying in nanoscale?

I calculated crystalite size using sharer equation and using most intense peak the value comes out in the range 4 to 7 Angstron. is it in nanoscale?
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Basic band structure reading

In band diagrams (e.g. GaAs below), symmetry points are sometimes indicated with a numerical index. I first thought it was the band index in the Bloch function (so two electrons with the same wave ...
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Solar cell: Surprising change in EL for varying PEDOT:PSS-thicknesses

I am currently working on improving a solar cell, which is partly transparent and therefore utilizes two transparent electrodes (TCO on top and PEDOT:PSS on the bottom). As PEDOT:PSS alone is not ...
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What is the effect of dopant on the crystalite size?

Crystal size decreases with doping and then increases with increase in dopant concentration, why? the ionic radii of dopant is greater than the host atoms.
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creating eh-pairs in a semiconductor -> conduction or valence band?

When a beam ray respectively a photon creates an electron-hole pair in a semiconductor, e.g. for silicon the ionization energy is 3.6 eV, is the electron then directly in the conduction band? So does ...
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Why is silicon absorbing visible light?

Here it is shown that silicon absorbs visible light: but the band gap energy for direct transitions is 3.6 eV which does not match to this absorption coefficient. Instead, the band gap energy for an ...
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Why is the necessary energy for a photon to lift an electron higher than the band gap energy?

The band gap energy of silicon is around 1 eV and though the required energy for a photon to lift an electron up into the conduction band is around 3.6 eV. Why is this? Is the Energy of an absorbed ...
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63 views

Why is the Fermi level (energy) shfited in doped semiconductors?

According to the Fermi level is shifted due to doping: Upwards in case of n-type and downwards in case of p-type. Why is this? The Fermi level is the level where the probability that an electron ...
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Why is the carrier distribution / density of states different in doped semiconductors?

How can it be explained that the carrier distribution is different in case of doped semiconductors? I understand it naturally, that the distribution of electrons is higher for n-type semiconductors. ...
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29 views

How many photons will a scintillation crystal emit?

The question is already in the title: How many photons will an excited scintillator emit? It is probably mainly given by the energy of the impinging particle and the bandgap energy. But also probably ...
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Electromagnetic wave and skin depth, skin effect

In EM theory concept of skin depth is induced which is a measure of how much a EM wave can penetrate the medium, from it arises the concept of skin effect which is for EM wave but we use this to ...
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Method for making graphene plausible?

Gallium does not wet quartz or graphite. I’m pretty sure graphite doesn’t stick to quartz (or not well) especially if smooth. So what if on a round flat plate of polished fused quartz you set a small ...
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In semiconductor physics, in context of PN junctions/pixel detectors, what is the difference/meaning of N-in-N and N-in-P technology?

In semiconductor physics, in context of PN junctions/pixel detectors, what is the difference/meaning of N-in-N and N-in-P technology ? How could we have a N-N diode ?
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Combined effects of strain and doping on the electronic structure of semiconductors

I've read papers in DFT studies on band gap tuning in semiconductors and the usually studied methods are either through doping or application of external strain. But its always just one or the other. ...
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Find electron-hole recombination rate? [closed]

In an n-type semiconductor, the thermal equilibrium electron concentration (n0=1015/cm3) and the intrinsic carrier concentration (ni=1010/cm3). The mean life time of minority carriers is 1us. The ...
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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 to 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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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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64 views

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

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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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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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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3answers
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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 ...