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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How does photovoltaic effect work?

If I understand it correctly, due to diffusion and something like a concentration gradient, a gate layer is formed at the PN junction (at P there is more space=holes, at N there are a lot of packed ...
John's user avatar
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Collector-base biasing in pnp transitor as amplifier [closed]

For a pnp transistor in common emmiter configuration used as an amplifier, what is the collector-base junction biasing? I found out on internet that it is forward biased thus both the junctions are ...
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Exciton Brillouin Zone

In an excitonic calculation, one can have an eigenvalue equation which leads to the expectation value expression as follows: $$\langle E_{ex}(\vec{Q})\rangle=\int_{FBZ} \phi^*(\vec{k})[E_c(\vec{k})-...
L_J's user avatar
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What is the effect of temperature on the Fermi level of an extrinsic semiconductor

It is written that on increasing the temperature the Fermi level of an extrinsic semiconductor moves towards the centre of the energy gap. But while solving on numerical, given as in an in an n type ...
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For intrinsic semiconductors, is the gap Energy equals $E_c-E_v$ or $E_c+E_v$?

So I have a problem with the intrinsic Fermi Level because by definition it is in the middle of the gap energy, and knowing that Eg=(Ec-Ev), we should have Ei=(Ec-Ev)/2. But when we follow the ...
anass bakour's user avatar
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Definition of Hall's current

Dear fellow physicists! I come to you with a question regarding the definiton of the Hall current. The only sentence close to definition of this concept, I have found after extensive search on the ...
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Can a DC voltage excite a pure semiconductor (or insulator) from the valence band to the conduction band?

I have a question I am sticking around and can't find a satisfying answer. Say I have an intrinsic semidonductor at zero Kelvin (no electrons in conduction band). I apply a DC voltage across it. Can ...
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How is the energy per electron in Sommerfeld Theory interpreted?

I'm having a hard time understanding the way the energy per electron is calculated in Sommerfeld Theory. From the N.W.Ashcroft book on solid state physics it is done by first calculating the ground-...
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How a switching mixer works in this example circuit?

I am reading about lock-in amplifiers and came across this example circuit of a mixer: You have one sinusoidal input signal $e_1$ with a phase $\phi_1$ and the local oscillator has a square-wave ...
NeonGabu's user avatar
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Temperature dependence of chemical potential in a semiconductor

My professor just uploaded the following two foils: and Now I understand that if temperature increases we have some electrons in the conduction band and some holes in valence band, which would (I ...
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Interpretation of velocity in the de Broglie wavelength of an electron in a crystal

The de Broglie wavelength of a free electron is $\lambda = h/mv$ whre m is the free electron mass, and v is the velocity. Often in introductory solid state physics literature (review articles, lower-...
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Vacuum Tube Furnace Sealing Flange Design

I know this is not the best place to post this question, but in an effort to get the most prompt and direct response I chose this forum. Can anyone suggest a good reference to the design parameters ...
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How would surface dipoles change the internal potential in a conducting sphere?

In the nanoscience literature, there is a model of semiconductor nanoparticle doping which ascribes the effect to surface dipoles shifting the absolute state energies relative to the environmental ...
intraband's user avatar
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$\rm InP$ Mach-Zender modulator

I know how a Mach-Zender electro-optical modulator (MZM) works when based on non-linear crystals like LN. On-chip realization of MZMs is often done with $\rm InP$ that is a semiconductor. What is the ...
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Saturation region of common emitter BJT

About the saturation region of common emitter Bjt it's written that In saturation mode both of the "diodes" in the transistor are forward biased. That means V(BE) must be greater than 0, and ...
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Why doesn't the voltage across this diode follow the voltage from the power supply?

Why the voltage across the Load resistor $R_L$ remains constant at 0.7 volts as long as the diode is forward biased? Both diode and load resistor are parallel so the voltage across them should be ...
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The electric Field inside PN junction in reverse bias

In the unbiased PN junction the electric Field inside the depletion region is just due to the fixed charges inside it But what happens in case of reverse basing ? In case of reverse bias the reverse ...
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When forming an n channel in an N mosfet, do the pn junctions of the drain-substrate and source-substrate parts disappear?

When forming an n channel in an N mosfet, do the pn junctions of the drain-substrate and source-substrate parts disappear? Here's what I expected: When gate voltage (higher than threshold voltage) ...
KHJ's user avatar
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How can an electric current flow between the end of the channel and drain?

In my book, it explains why current can flow even if the channel ends: The device still conducts: as illustrated in figure, once the electrons reach the end of the channel, they experience the high ...
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$\mathbf k\cdot\mathbf p$ Hamiltonian

I am looking into the $k\cdot p$ Hamiltonian approach to describe a semiconductor system. The simplest system appears to be the 2x2 system which can be visualised as: \begin{pmatrix} \epsilon(k) &&...
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Bloch functions and covalent bonds in some semiconductors

In a Group IV semiconductor (like Si, Ge), one atom makes 4 covalent bonds with its neighboring atoms. They create in this way the so-called a tetrahedral bond (that of the diamond structure). Each 2 ...
Anky Physics's user avatar
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Is the direction of base current always constant in a BJT transistor?

Is the direction of base current always constant in a BJT transistor? Excluding the transistor breakdown state, is the direction of the base current always the same in the four modes: active mode, cut-...
KHJ's user avatar
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Voltage across the diode?

Why the voltage across an ideal pn junction diode remains 0.7 volts, even when the applied voltage exceeds 0.7 volts? Shouldn't it be the applied voltage minus the 0.7 V?
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Asymmetric-Bipolar Pulsed-DC Magnetron Sputtering - Strontium Target

Can a Strontium target be deposited on a substrate utilizing asymmetric-bipolar pulsed-dc magnetron sputtering?
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How to separate electron and hole mobilities in a intrinsic semiconductor?

I read in textbooks that the electric conductivity of a semiconductor is $\sigma=q(n\mu_n+p\mu_p)$, where $q$ is an electron's charge, $n$ and $p$ are the concentrations of electrons and holes, $\mu_n$...
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How to read these 0-1 diagrams? I dont know whether the circles mean 0 or 1 [closed]

This is a diagram for the input signal through a logic gate circuit, but im not sure whether the points where jt goes up/down signify a 0 or 1.
iCarry's user avatar
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Definition Of Saturation current

In [wikipedia] article about Saturation current(https://en.wikipedia.org/wiki/Saturation_current), they define this as The saturation current (or scale current), more accurately the reverse ...
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If an atom loses electron, it becomes a cation; it does not form a hole. However, when electron is lost from a bond, it forms a hole and not a cation

If an atom loses an electron, it becomes a cation, and when an electron is lost from a bond, it forms a hole. This is what the professor told the class, but I am not able to find the reason for that ...
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Is the current of a SPAD a digital signal? (Question about Avalanche process)

I understand that when a Single Photon Avalanche Diode (SPAD) is biased and a photon hits it, an avalanche process is activated that cause a current. What happens if two photons hit it? Will the ...
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Definition of Fermi level

In wikipedia article, there is following sentence. The Fermi level of a solid-state body is the thermodynamic work required to add one electron to the body. It is a thermodynamic quantity usually ...
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Pn junction and the structure of diodes

I've read the part about pn-junction from Manfred Albach's "Elektrotechnik" book and I've seen some resources online as well. However, there are a few questions that bother me and prevent me ...
Electricity's user avatar
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Extension from Excitons to Trions

I am curious about the fundamentals of how a trion state is defined. An exciton state is considered a bound electron-hole pair. This can be formed by is we have a ground state which consists of a full ...
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Zener breakdown and Zener diodes

While studying reverse biased P-N junctions, I came across the phenomenon of Zener breakdown and its implementation in Zener diodes. I have the following queries- (A) What exactly is the reason behind ...
XXXMATHEMATICION's user avatar
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Where can I read about Valleytronics?

Where can I read about Valleytronics? Are there any good books or review papers on this topic? And which are the most influential papers? The question was also posted at the Matter Modeling site.
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Thermal Properties of the Free Electron Gas: Explanation of the $N$-particle systems and averaging over all $N$-particle stationary states

I have a master's degree in engineering and am trying to study more detailed topics in solid-state physics on my own. I have difficulties to understand the (2.38) $$P_{N}(E)=\cfrac{e^{-E/K_{B}T}}{\sum ...
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Understanding mixed trigger avalanche breakdown in pn junctions

I am reading a device physics text (Sze Physics of Semiconductor Devices, 3e, Chapter 2.4.3) and I am trying to make sense of the discussion of avalanche breakdown. The discussion is (over?)simplified ...
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Anisotropy of the effective masses in semiconductors

Recently, I have received a referee report on my paper in which reviewer states the following: "... in all known direct band gap semiconductors the electron effective mass is isotropic or has a ...
reterty's user avatar
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2 answers
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Why do logic ICs only have one transistor layer?

When looking at today's logic ICs, for example CPUs, those seem to consist of a very thin and dense layer of transistors, wired by a large amount of "metal" layers on top to complete the ...
dronus's user avatar
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Why we are using coupling capacitor in AC amplifier? [closed]

Why we are using coupling capacitor in AC amplifier?
Akshai PS's user avatar
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Depletion regime in MOS capacitor

(I originally asked this in Electronics SE, I was redirected here as this was a better place to post my question) I was watching a video lecture recorded by my Uni prof, where while dealing with the ...
insipidintegrator's user avatar
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Diode confusion

Consider the following diagram Here, the diode is in forward bias, and allows current to flow. However, I am slightly confused why this is the case. A diode is defined to only allow current to flow ...
Quin Gardiner Bax's user avatar
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Soliton in non-degenerate polymer

I just started reading about the conduction mechanism in polymer. From what i read, polarons are used as method of charge transportation in non-degenerate polymer. While for degenerate polymer, both ...
taqiuddin yusri's user avatar
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Basics regarding $k$-space axis and Energy graph in direct semiconductor

We can see from the graphic axes, that energy increases along the y-axis, and k space increases along the y-axis. Considering a direct or indirect semiconductor whichever it doesn't matter, but why ...
Fredrick's user avatar
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$\vec{k}\cdot\vec{p}$ Hamiltonian approach

I am new to reading into the $\vec{k}\cdot\vec{p}$ approach. Where for a periodic function $u_{\vec{k}}$, which satisfies the Schrodinger equation: $$ H_\vec{k}u_{\vec{k}}=E_{\vec{k}}u_{\vec{k}} $$ ...
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Why are no industrial diode lasers deep cooled?

Endurance lasers showed that a 633nm laser diode could lase as low as 621nm when cooled to almost -80C. The wavelength shift for diode lasers can surpass 0.3nm/‘C. From my limited experience ...
selene flemming's user avatar
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What is Ambipolar Diffusion in semiconductors?

I am following Neamen's book "Semiconductor Physics and Devices". I just could not come to imagine what Ambipolar Diffusion is and feeling very dumb. This concept of both carriers moving ...
Kartik Pandey's user avatar
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Calculating the ideality factor of a diode

I am carying out a semiconductor related experiment to calculate the ideality factor of a diode via I-V curves, here is the formula: Shockley Diode Formula I am trying to find n which is the ideality ...
DiodeEnthusiast's user avatar
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What determines the energy spacing of individual orbitals within an energy band in a material?

Within a material, electrons exist within energy bands, often referred to as the "conduction" band and the "valence" band (and I imagine there can be other named bands as well). I ...
Schoppe's user avatar
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Questions about CCD sensors and low temperatures?

The dynamic range of a CCD sensor increases at low temp, they say. What does this mean, and why does it happen? Near saturation a CCD sensor begins to exhibit non-linear characteristics. Is this in ...
Sven _Andersson's user avatar
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Wavefunctions of quantum point contacts

I have a question about the potential and wave functions of discrete energy levels of quantum point contacts. Assuming one has a rectengular potential well: Can the potential of the QPC be assumed to ...
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