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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Why defects don't have an effective charge in metals?
In semiconductors and insulators, crystal defects, e.g., vacancies and interstitials, are treated as having an effective charge. In metals, however, defects are treated as neutral. I can expect that ...
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A question related to shift in the Fermi energy [closed]
If the effective mass of holes in a semiconductor is 5 times that of the electron, at what temperature would the Fermi level shift by 15% from the middle of the forbidden energy band? (given that, eg =...
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How to Properly Discretize Semiconductor Continuity Equations
I am looking to perform numerical modeling of a MOSFET device and am wanting to better understand how to discretize the semiconductor continuity equations. The semiconductor equations consist of the ...
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Using Jacobi Method for Solving Full Semiconductor Equations
I am looking to perform modeling of a MOSFET device and have therefore been researching computational methods for how to do so. Quite often when solving the Poisson equation, the reader is pointed to ...
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Solid state devices, hole current [duplicate]
why do we consider hole movement as well as the electron movement in the total current term, the hole movement is the effect of the cause (electron movement), so how can they both contribute total ...
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Finite Difference Modeling of MOSFET Device
Does anyone know of any references for MOSFET modeling done using the Finite Difference Method that they could point me to? I understand the gist of the operation, namely using Poisson's equation to ...
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Why does an electron hole have a positive charge in semi-conductors?
From the link below, they explain when an electron in the valence band is promoted to the conduction band it leaves behind an electron hole. But in the case of the image below, we can see when Si is ...
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Is spin relaxation asymmetric in magnetic semiconductors?
I am considering photo-excitation in magnetic semiconductors (e.g. metal organic frameworks). The cartoon picture is like this:
where there will be a spin polarization in the conduction band since ...
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How is the number of charge carriers set free in an x-ray detector proportional to the energy of the incoming photon?
I'm a chemistry undergrad student and I've been doing some research into the ways light is generated and detected at different parts of the spectrum (for the purposes of better understanding practical ...
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Difference between the numerical values of the intrinsic carrier concentration $n_i$ in silicon
I've been working on the intrinsic carrier concentration for silicon, and if calculated with the formula
$$n_i = \sqrt{N_vN_c}\exp{\left(\frac{-E_g}{2kT}\right)}$$
taking the accepted values $N_v \...
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Semiconductor-graphene-semiconductor junction
In the literature, I've found Graphene-semiconductor junctions are treated as Schottky junctions. So by reverse-biasing a graphene n-semiconductor junction, we inject carriers into the graphene ...
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Why do dopant levels lie in the energy band gap of semiconductor?
Dopants create impurity levels in the band gap, this is what we were taught in semiconductor classes. And indeed that's what's seen in experiments (for example https://www.globalsino.com/EM/page2777....
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How can red LEDs still give a faint glow at a voltage of only 1.4V? [duplicate]
How can a red LED work at a voltage of only $1.4{\rm V}$? Red photons have an energy of $1.77{\rm V}$ if we use $\lambda = 0.7\mu\text{m}$ in the relation:
$$ E = \hbar \omega = \frac{2\pi\hbar c}{\...
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How does the Fermi level of graphene change if it is placed in a biased pn junction or in a plate capacitor?
I ran into a problem on which I can't really find any solutions in literature. I am looking at a Graphene sheet that is sandwiched in a biased pn junction (current flows orthogonal to the Graphene ...
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Graphene dispersion at Dirac points
After deriving the dispersion relation of graphene:
$$ E(k) = \pm t \sqrt{3+2\cos{(k_y \sqrt{3} a)} + 4\cos{\bigg(\frac{3a}{2} k_x \bigg)} \cos{ \bigg(\frac{\sqrt{3}}{2}a k_y \bigg)} } $$
how do I see ...
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Why would a depletion "layer" form in a PN junction?
I understand that electrons diffuse from the N to the P region due to the concentration difference. This diffusion of electrons creates an electric field opposing further diffusion.
What I don't ...
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Where can I read about excitons?
I'm having a tough time finding a good reference for excitons. I know next to nothing about them, and I'd like to find a good book/paper/notes that would introduce it in a slow, pedagogical way. ...
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How do solar cells really work?
When I read articles on the workings of photovoltaics, the explanation tends to revolve around the idea of PN-junctions, and how an electric field separates charges (electrons and holes). In a Quora ...
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Thermal Smearing in Josephson Junction
I'm basically trying to simulate a josephson junction at a particular temperature. As per some of the plots I could find, the rise in temperature leads to a rounding of the I - V curve. I was ...
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Resistively and Capacitively Shunted Junction (RCSJ) Model of Josephson Junction Numerical Solution
I'm trying to write a program to plot the I-V charateristics the josephson junction using a python program for some given values of resistance $R$, capacitance $C$, and critical current $I_0$, using ...
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Why do we need to consider interaction for doping atom?
In semiconductors, the intrinsic carrier concentration is calculated by Fermi-Dirac distribution, but for the situation of doping, we need to consider the Coulomb interaction for doping atom, and the ...
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Fermi-Dirac integrals of different orders
Which physical quantities are related to the Fermi-Dirac integrals of different orders?
If fermi-dirac integral, write like this:
$$F_\xi(\eta_c) = \frac{1}{\Gamma(\xi+1)} \int_{0}^{\infty} \frac{x^{\...
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Does diffusion current "consume" thermal energy?
My (possibly erroneous) understanding of solid state physic has led me to the belief that diffusion current may "consume" thermal energy.
Here is my (possibly erroneous) understanding. When ...
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Doping density dependence on effective density of states Si pn junction
I would like to know how the doping density influences the effective density of states in a pn junction. For example the classic relations used to determine this is
$$N_c = 2\left(\frac{2\pi m_n^* k_B ...
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Connecting semi-conductors to outside wires
I know about semi-conductors, and https://en.wikipedia.org/wiki/Schottky_diode .
Question is: how is a transistor or a more complex semi-conductor wired to the metal outside without accidentally ...
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C$_{60}$ fullerene electronic structure, C$_{60}$ insulator
I read a post on Chemistry stackexchange, how to explain that C$_{60}$ is an insulator. The common ground seemed to be that -- in contrast to graphene -- a C$_{60}$ solid consists of separate ...
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Intrinsic band gap vs work function of doped semiconductors
I'm confused about this question on doped semiconductors:
Question: Photoelectrons with a maximum energy of $\ 0.5$ eV are observed when light of wavelength
$500$ nm is incident on a heavily n-doped ...
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How exactly does a p-n junction operate when biased by current *not* voltage?
I'm trying to understand on the Fermi-level of the P-N junction, what happens when I bias a diode via an ideal current source ? I understand how the energy levels behave when biased via voltage source,...
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What is the relationship between the applied reverse bias in a p-n junction to the band gap of the semiconductor?
Consider a p-n junction under reverse bias. The difference in the Fermi Energy of the p-side and the n-side is $qV_r$ where $q$ is the elementary charge, and $V_r$ is the applied reverse voltage. What ...
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Electromotive force by PN junction and extraneous role of electrolyte in electrochemical cells
When the two semiconductors N and P are connected, because of higher Fermi energy, electrons migrate from N to P so that an electric filed is formed in the depletion region (attached picture) which ...
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