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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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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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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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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29 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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56 views

Which heat equation should I choose if I want to toggle between conductive and convective heat transfer?

I have a science project where I have an aluminum cylinder, filled with oil, with a diode chain floating inside of it. The diode chain has a bimetallic temperature switch on it that turns off the ...
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45 views

At what pressure do semiconductors break down? [closed]

So let's say you were going to send some electronics to the bottom of the ocean, 3-5km down. This would be about $5km*1000kg=5Mkgf/m^{2}$. So at what pressure do circuit boards, transistors, etc stop ...
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124 views

Mobility of electrons and holes

According to experimental results it has been found that in Silicon holes are one-third as mobile as electrons. But if doping is considerably low such that phonon scattering is dominant over impurity ...
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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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141 views

Why is Zener breakdown of a PN junction reversible but avalanche breakdown irreversible?

I have read in my textbook that if a PN junction is in Zener breakdown and if we now reduce the external voltage, the PN junction is not damaged and returns back to its initial state. However, the ...
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59 views

Fermi-Dirac Function

Why do we assume complete ionization of donor energy level (any doping level) even if we know that when Ef will be closer to it, the probability of electron finding will increase? Context- ...
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Characteristic curve of a solar panel

I have trouble understanding the $I(U)$-plot of a solar panel: So without any light it should probably just be the characteristic curve of a diode, right? Which means that at some point, when the ...
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280 views

What is the difference between a dielectric and a semiconductor?

It would be very nice if you could give an equation to discern the two material classes. Please do not provide an answer which is based on the band gap size, since in the last years also diamond (...
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What is a pump reflector?

I understand the meaning of laser pumping. But i don't understand what is a pump reflector. As a clear definition does not appear online. In the paper,DESIGN AND DEVELOPMENT OF WIDEBAND HYBRID RAMAN/...
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91 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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201 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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Thermo-electric current in the p-type semiconductor

I came across this picture : Source:thermo-electric generators Basically, within the p-type semiconductor, I don't know how holes move from the hot side to the cold one. How does this happen? If ...
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Are there any other bands except for valence band and conduction band in any material?

When atoms or molecules are brought together to form a lattice, outermost orbit electrons gain discrete energy levels and when these energies are classified they group into valence band and conduction ...
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65 views

Can Hall Voltage be used to glow a bulb?

The voltage developed along the semiconductor i.e perpendicular to magnetic field and current flow be used to glow a bulb? When hall voltage develops what happens to potential drop across the ...
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221 views

Why does the depletion layer of a p-n junction diode decrease in width upon forward biasing?

The current in the direction of intrinsic diffusion increases, as the potential barrier decreases. I'm okay with that, but I feel that the dip in potential barrier has nothing to do with the width of ...
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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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Why the product of hole and free electron density is constant in semiconductor?

I have learned from a text book of electronics that the free electron density, n (which is equal to that of hole, p) of intrinsic semiconductor due to thermal excitation is a function of temperature ...
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1answer
114 views

How can I calculate the chemical potential and the effective masses in an intrinsic semiconductor?

I want to calculate the chemical potential and the effective masses of the germanium charge carriers considering that the relaxation time is the same for the two carriers: electrons and holes. ...
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what is the ionization rate?

I'm wondering about the term "ionization rate". Especially in respect to silicon/semi conductors and electrons & holes. I do not understand why there is a difference between electrons & holes. ...
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Why is silicon used for making solar cells?

Silicon has a bandgap of 1.1 eV, whereas germanium has 0.65 eV. Silicon has an indirect bandgap, whereas gallium arsenide has a direct bandgap. Still silicon is mainly used for making solar cells. Why?...
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Gauss's Law about excess charge on conductors, quantum mechanics, and doped semi-conductors [closed]

Does quantum mechanics predict that there is any probability of finding excess charge inside a conductor? I've read an explanation about the distribution of excess charge placed on conductors. 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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How to find the degree of doping in a material?

I find this term a bit mysterious, it appears that everyone is using it intuitively without proper definition (or at least I failed to find one). So the Physics Glossary defines it as In condensed ...
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135 views

How to utilize the Rashba effect in spin field effect transistor?

The conventional nano-electronics are confronting many bottlenecks and spin-based devices have become the candidate for the next-generation nano-electronics (spintronics). A semiconducting channel ...
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54 views

In HPGe detector how electron-hole pair remembers energy information of incident gamma?

In the HPGe detector, any gamma energy (> e-h pair production E) shall excite the electron of the valence band and send it to the conduction band. Due to reverse bias, the conduction band e shall be ...
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48 views

What does ground in low voltage electronic circuits mean?

I have been confused a lot by the word "Ground". The ground that I've usually heard about is connecting a wire of appliances with the rod buried under earth but what does the word Ground mean when it ...
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Conductivity of a heavily doped semiconductor at Absolute zero temperature

As the Fermi level moves toward the conduction band in an n-type semiconductor; when heavily doped, it moves into the conduction band of the semi conductor. So, will the semi conductor behave as a ...
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160 views

How do electron holes have spin, and how do they interact with “real” particles / vice versa?

So, I thought I had an uneasy truce with quantum mechanics but I read something today which made spotted combat flare up in my mind again. In solid state semiconductor free electrons certainly have ...
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122 views

What does it mean if the resistance of a semiconductor increases due to light?

I have synthesized an $n$-type semiconductor material $\text{ZnO}$. Under light illumination, its resistance keeps increasing. What are the reasons for this?
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Velocity normal to surface in thermionic emission

In the derivation of the Richard-Dushman law which relates the current density $J$ from thermionic emission in a filament of temperature $T$ and work function $\phi$ $$J = AT^2e^{-\frac{\phi}{kT}}$$ ...
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Bjt configuration

In common base configuration,we know that alpha is almost 1 which means that the base current is almost zero.But what is the physics behind this base current almost equal to 0?And similarly in common ...
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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 ...
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How relate doping concentration and electron concentration?

Say I have Si with the donar doping concentration $N_D=10^{14} \text{cm}^{-3}$ and a temperature $T$. How can I relate the donar doping concentration to the electron concentration? I know the ...
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61 views

Is diamond able to conduct electricity given 5.5 eV of energy? How do we then identify insulators and semiconductors?

I have learnt that the band gap for diamond, an insulator, is $5.5\:\rm eV$. Does this mean that diamond is able to conduct electricity if we give it this immense amount of energy (let's assume we do ...
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Doubt with another form of Balmer' Series

In the book I'm studying from (Solid state electronic devices - Ben Streetman) it is said that the Balmer series is defined as follows: $$ v = cR \left( \frac{1}{2^2} - \frac{1}{n^2}\right) $$ with c ...
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81 views

LED diode: How are photons produced in the LED diode?

According to "Introductory semiconductor physics" by Greg Parker (1994; Amazon.com), a photon is produced when an electron recombines with a hole across the energy gap of a direct band-gap ...
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330 views

How can depletion region be formed at the center?

Let's consider an electron at the junction in the n-type region. As it moves into the p-type we say it leaves behind a positive ion and hence in this way electrons at the junction in the n-type create ...
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2answers
101 views

Existence of conduction electrons in pure Si at room temperature

Silicon has a bandgap of ~1.1 eV whereas the room temperature thermal energy is ~0.04 eV. But we still find electrons in the conduction band for a pure silicon wafer, away from any radiation. I ...
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1answer
56 views

Who controls completing the circuit in a transistor? [closed]

Consider an npn junction. The p-type semiconductor p has holes which are filled by electrons provided either by the n-type or by phosphorous dopants. The transfer of charge from n to p forms a ...
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57 views

Mental contradiction: Valence electrons do not move at the non-zero wavevector?

I have a mental contradiction. Let's consider the following band structure with the Fermi energy somewhere inside the gap: where $\Gamma$ point represents the zero value of the wavevector $|\vec{k}|$....
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Dark current and thermal excitation in CCDs

In charge-coupled devices (CCDs), doped semiconductors are used to produce an electronic signal from incoming photons - the underlying principle being the photoelectric effect. This simple law tells ...
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395 views

Why is it not possible to dope semiconductors with elements with 6 or 2 valence electrons?

As far as I have learnt, semiconductors are often made using elements from the 4th group, and their properties are often enhanced by doping with either pentavalent or trivalent elements. Take the ...
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By shortening the N-type side to the P-type side of a diode with a wire, how does the electric potential looks like in each point of this circuit?

To avoid misunderstanding I'll first start with the notions. The electrochemical potential (which in semiconductors refers to as the Fermi level) is the sum of the chemical potential and electrical ...
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154 views

Is Fermi Level a property of the material?

I have gotten myself confused about the band structure explanation of semi-conductors vs insulators. The Wikipedia picture and the explanation surrounding it seem to suggest that Fermi Level is a ...