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# 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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### Finding the carrier concentration of semiconductor

Silicon (4 valence electrons) can be doped with arsenic (5 valence electrons) to make an n-type semiconductor. Assuming 1 in every 15 million silicon atoms is replaced with arsenic, calculate the ...
23 views

### Question about built in voltage in p-n junction

If I have two materials, joined together to make a p-n junction, the $V_{bi}$ is found by calculating the difference between the conduction bands or LUMO levels. Should this be the same as the ...
36 views

### Why does diode built-in voltage persist when current begins flowing?

When P and N type semiconductors are connected together, some of the electrons drift from the N type into the P type to recombine with holes. This leaves positive ions on the N type and negative ions ...
327 views

### Why does the depletion region shrink in a forward biased p-n junction diode?

I was studying about semiconductors and I came up with a doubt in my mind . Let us assume a p-n junction diode is in its steady state in unbiased condition that is no charge is flowing through the ...
85 views

In weak field non-equilibrium dynamics, mobility can be calculated by Einstein relation $\mu=\frac{eD}{K_BT}$, where $D$ is diffusion constant. Mobility can also be calculated by the definition $\mu=... 0answers 85 views ### Attempting to calculate the mobility from SCLC measurement (space charge limited current) I performed an SCLC measurement on a p-type material (hole transport layer) for a solar cell. Referring to the wikipedia page:https://en.wikipedia.org/wiki/Space_charge The relationship between$J$... 0answers 32 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? 0answers 42 views ### Further doping p-type material. Why doesn't this increase the hole mobility. etc? I did a project in which I made perovksite nanocrystal solar cells. The hole transport material was doped with another p-type material and performance was compared. It turns out that this didn't ... 1answer 56 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 ... 0answers 26 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 1answer 50 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 ... 1answer 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. ... 2answers 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 ... 1answer 47 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 ... 1answer 143 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 ... 0answers 34 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 ... 1answer 179 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 ... 1answer 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- ... 1answer 39 views ### 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 ... 2answers 327 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 (... 1answer 50 views ### 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/... 1answer 95 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 ... 1answer 216 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 ... 0answers 48 views ### 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 ... 1answer 29 views ### 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 ... 1answer 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 ... 2answers 230 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 ... 1answer 46 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) ... 0answers 28 views ### 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 ... 0answers 129 views ### 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 ... 1answer 120 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. ... 1answer 44 views ### 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. ... 7answers 5k views ### 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?... 0answers 48 views ### 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 ... 1answer 35 views ### 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? 2answers 112 views ### Why diodes can be used to create a current-independent voltage drop? [duplicate] How is current independent of the voltage drop in a diode? 1answer 94 views ### 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 ... 1answer 147 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 ... 1answer 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 ... 1answer 52 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 ... 0answers 93 views ### 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 ... 1answer 193 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 ... 1answer 126 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? 0answers 22 views ### 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$$$J = AT^2e^{-\frac{\phi}{kT}}$$ ... 1answer 63 views ### 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 ... 1answer 63 views ### 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 ... 0answers 30 views ### 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 ... 1answer 65 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 ...
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 ...