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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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JFET (physics - electronics) [on hold]

In the case of dc biasing or self biasing of a JFET, we apply dc inputs. So, what's the definition of Q point in that case??
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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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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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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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What does it mean if the resistance of a semiconductor increases due to light?

I have synthesized an n-type semiconductor material (ZnO). Under light illumination, its resistance keeps increasing. What are the reasons for this?
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Vanishing of Coulomb blockade/charge dispersion in high transparency Josephson junctions

I was recently reading the paper Coulomb Blockade in Superconducting Quantum Point Contacts by Averin from 1999 (see here for the ArXiV, here for the PRL). In here he discusses a peculiar phenomenon:...
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Richardson-Dushman Equation using Momentum Space

How can we derive the Richard Dushman Equation using momentum space? J=B$_0$T$^2$e$^{-(\phi/kT)}$, B$_0$=4$\pi$qmk$^2$/h$^3$ Am$^{-2}$K$^{-2}$, T=Temperature in Kelvin, $\phi$ is work function of ...
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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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27 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 ...
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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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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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Fermi Level and Built -in potential of semicoductor

How can built in potential barrier of semiconductor be determined as the difference between fermi level in p- and n- side region ?
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Can electron/holes be contribute to the photocurrent when absorbed outside depletion region

I am not convinced by the common interpretation that photons can only contribute to the photocurrent when they are absorbed in the depletion region. For the photodiodes I have been studying, the A/W ...
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1answer
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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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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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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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Why is the energy required to create an electron-hole pair in semiconductors higher than their band gap energy?

I am studying semiconductor physics and in more than one book I have found that the energy needed to create an electron-hole pair in Si and Ge is a few times higher than the band gap energy. For ...
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2answers
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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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activation of donors via annealing

I've been reading up on semiconductors and quantum computing in general and have come across "activating donors via annealing" a lot, in papers such as here for example. From what I gathered, they ...
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53 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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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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Substitution of $-E_F-E_g$ for $E_F$ in distribution function and transport integrals for holes

As far as I understand, holes occupancy governed through distribution defined as follows, $h=1−f=1−\frac{1}{e^{\frac{E-E_F}{k_BT}}+1}$ but when I tried to calculate transport coefficient involving ...
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2answers
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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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1answer
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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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What is charge relaxation and spin relaxation in an atom/ artificial atom?

I want to understand the difference between these two terms.
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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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What the difference between pin and pn diodes i-v curve?

For my understanding there should be no big difference in i-v curve between regular p-n junction and p-i-n junction, the only difference i can think about is do to the bigger resistance of the ...
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What is the physical interpretation of energy band graph in semiconductors?

Does this graph represent energy states in a single atom which makes it into the semiconductor or is this a representation of sum total of energy levels occupied by different electrons in the lattice ...
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When Pin diode is no longer junction?

For p-i-n junction with intrinsic region d, I need to answer what happened when d is very large. So from simple logic, I believe that at some point there will be no diffusion of charge carriers from p-...
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21 views

Built In voltage drop across a pnn+ device

Will the net built-in potential of an p+,n,n+ device having two junctions(1.) that of p+ and n and 2.) that of n and n+ simply be the addition of the built in potentials of the junctions?
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Meaning of F(E)Z(E) in semiconductor theory

I really don't understand the following term $$ \int F(E)Z(E)dE$$ where $F(E)$ is the Fermi-Dirac distribution (but it could be any distribution) and $Z(E)$ is the density of states. What I really ...
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Confusion regarding Hall effect in semiconductors

In many places, it's mentioned that in hall effect, the holes move under the influence of magnetic field in the direction as shown in the figure. In this figure itself, the bound electrons move in the ...
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certain bulk structure avalanche photo diode (multiplication stage)

I've a bulk structure from a photodiode from hamamatsu. There are quite a lot explanations and so on available for a typical avalanche photodiode: Above image is from hamamatsu. Nevertheless I also ...
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Charge carrier in avalanche photodiodes

Why is the drift current/avalanche multiplication in avalanche photodiodes mainly build of electrons? And not also on holes since electrons are "always"(?) refered to electron-holes in semiconductors?
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Ballistic FET with channel made of ferromagnetic semiconductor

How do I find the characteristics, features, and differences of a standard ballistic FET (Field Effect Transistor) if the channel is made of a ferromagnetic semiconductor. Any papers/leads on how to ...
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How does a hole do impact ionization?

Impact ionization is said to be generation of electron-hole pairs with help of free electrons and holes. I have the intuition on how a free electron would be able to generate electron hole pair. I can'...
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reverse / dark / leakage current

what is the difference between reverse, dark and leakage current of a (photo-)diode? From my current understanding it all seems to be the same?
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SiO2 layer in diodes

Can somebody please explain the purpose of this SiO2-layer? Thank you!
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Link between tunneling rate and conductivity

Generally speaking, in the theory of single-electron tunneling events (one electron tunneling through a quantum well), the rate under which this event occurs is calculated using Fermi's Golden Rule, ...
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1answer
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Doping in semiconductors - location of new states

A short question relative to doping semiconductors: What defines the location of new energy states? For example, why does doping of n-type add energy states slightly below the conduction band (and not ...
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1answer
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is semiconductor in thermal equilibrium?

If a semiconductor is heated such that there is no temperature gradient, is it under thermal equilibrium? I have studied that if no temperature gradient exists across a semiconductor then it's in ...
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Impurities in HPGe crystals

Is there any way that one can find the impurities existing in an HPGe crystal? This is required for making an accurate simulation of the material of the crystal including the concentrations of Ge and ...
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Reverse barrier potential

I have studied that the reverse barrier voltage of a diode connected to a battery is equal to the barrier voltage of the diode under no bias plus the voltage of the battery. If we apply Kirchhoff's ...
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2answers
268 views

Is Fermi level located above or below donor levels in n-type semiconductor?

I find contradicting information about this. Some resources says it's above donor levels Hyperphysics website: and other say it's below, eg. on this ResearchGate thread: in n-type semiconductor,...
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Change of refractive index using semiconductor

I was wondering, if it is possible to change the refractive index of a semiconductor using an electric field or current? I have heard about injecting charges to tune the refractive index. How/Why does ...
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1answer
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Change Carrier Density Of Semiconductor [closed]

Do you know how you can actively modulate the carrier density in a semiconductor ?
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1answer
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How does base-emitter voltage affect the current gain of a transistor?

I'm doing a Physics project related to transistor operation. My data shows that as the base-emitter voltage drop increases, the current gain of the transistor rises and eventually plateaus at a ...
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1answer
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Photoluminescence Spectroscopy- Two individual spots, different colors, but same emission spectra

my apologies in advance if I'm not posting at the right site, but StackExchange-Physics is the closest one that relates to this question. Method: Photoluminescence spectroscopy Sample being studied: ...