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 affect it.
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Modern and complete references for the $k\cdot p$ method?
I've recently started studying the $k\cdot p$ method for describing electronic bandstructures near the centre of the Brillouin zone and I've been finding it hard to find any pedagogical references on ...
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Ionized Depletion Region, Why aren't those charged being excited?
Ok so I understand the PN junction, and how when 2 Semiconductor materials are placed together the Electrons will jump into the Holes near the junction creating a Negatively Ionized Atoms on the ...
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What are “electron holes” in semiconductors?
I'm tutoring senior high school students. So far I've explained them the concepts of atomic structure (Bohr's model & Quantum mechanical model) very clearly. Now the next topic to be taught is ...
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5answers
528 views
Derivation of Schrodinger equation for a system with position dependent effective mass
How to derive the Schrodinger equation for a system with position dependent effective mass? For example, I encountered this equation when I first studied semiconductor hetero-structures. All the books ...
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2answers
81 views
Is it viable or possible to make your own transistor?
Just wondering if it is possible/viable to construct your own transistor, not small like todays, but the same scale as the one created at Bell Labs.
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983 views
What's a typical electron-hole recombination time of semiconductors?
Have some trouble finding a useful reference to answer the following questions:
What's a typical electron-hole recombination time of semiconductors? And how does it depend on the temperature and the ...
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154 views
how does zener diode maintain potential across its terminals?
My physics book has a topic about zener diodes being used as voltage regulators in the reverse bias.
Well, I'm curious to know how does the zener maintain the potential across its terminals after it ...
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1answer
332 views
Can electrons move through vacuum?
I studied that electronics is the branch of physics which deals with the practical applications of moving electrons through vacuum, semi-conductors and gasses. Can electrons move through vacuum?
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1answer
1k views
What is injection level (semiconductor physics)?
I am currently reading journal articles about semiconductor physics in solar cells. What is injection level?
I'll try to start off with what I understand. Photons hitting the silicon cause its ...
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1answer
116 views
Donors/Acceptors in Metal Oxides
Can anyone explain to me why most articles describe chromium as an acceptor in titanium dioxide? In TiO2, titanium has the charge state Ti$^{4+}$ and oxygen has the charge state O$^{2-}$. When Cr ...
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2answers
308 views
Purchasing semiconductor substrates
I'd like to make a comparison of prices, availability and properties of semiconductor substrate layers like Si, Ge, GaP, AlN etc. I wonder what are the problems related to getting such data, what are ...
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4answers
481 views
(If and) Why does cold temperature affect semiconductors?
I had a college student build an overclocked PC using phase-change technology. (This is essentially an air-conditioning unit with the evaporator attached directly to the motherboard.) He said that ...
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1answer
519 views
Selection rule used in singlet/triplet recombination in LEDs
In organic light emitting diodes, only singlet excitons contribute to the light emission (this is flouresence). Everything I read, say that triplet excitons cannot recombine on the same timescale as ...
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186 views
What limits the maximum attainable Fermi Energy for a material experimentally?
Either through doping or gating. What are some good terms to search for if I'm looking for some experimentally obtained values for particular materials? I'm particularly interested in what the limit ...
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1answer
62 views
Why does the Gallum-Arsenite bandgap narrow for higher temperatures and is this because of unavoidable impurities?
I found this sentence:
GaAs at 300K contains 10^15 acceptor atoms per cubic centimeter.
The bandgaps for Gallium Arsenite are:
0 Kelvin : 1.518 eV
300 Kelvin: 1.424 eV
Now I am wondering:
...
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1answer
105 views
Theory of Space Charge in a Planar Diode
A planar diode in a vacuum bulb can support current in only one direction. To even get current flowing, you have to heat up the cathode filament to excite the electrons. However, once current is ...
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1answer
386 views
Energy levels in disordered organic semiconductors?
Now in disordered organics, the band picture is thrown out the window, from what I can tell (due to lack of symmetry). But don't HOMO/LUMO levels basically take the place of conduction/valence bands ...
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70 views
Semi-conductors
Suppose there is a semiconductor with Fermi energy $E_f$ and that there are $N$ bound electron states.
I'd like to know why the mean number of excited electrons takes the form $$\bar n={N\over ...
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107 views
Estimation of the internal electric field strength in the pn-junction
I would like to compare my result in an order of magnitude. So, How can I estimate the strength of the electric field in a typical Si PN-junction?
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1answer
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Confused about charge seperation in solar cells
I'm a bit confused about how solar cells work.
My understanding is that there is a p-n junction. A photon is absorbed which creates an electron-hole pair, and the idea is to separate the electron ...
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0answers
238 views
Turn-on delay time for Laser diode
Do you know any simple explanation on the reason why the turn-on delay time on a laser diode is reducing while we increase the bias current?
Turn on delay,is the time that the laser needs from the ...
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1answer
307 views
III-V semiconductor compounds - band gap approximations
I'm looking for the most common and accurate approximation functions for III-V semiconductor compounds. So far, I found two (InGaAs as the sample compound):
The simplest one: ...
2
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2answers
451 views
Taylor approximation in physics
In a textbook about semicoductor physics, I came across a passage about deriving the carrier concentration at thermal equilibrium in semiconductors I didn't quite grasp:
The recombination ...
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2answers
136 views
Would HgTe be a topological insulator?
In "Quantum Spin Hall Insulator State in HgTe Quantum Wells", researchers observed a 2D topological insulator by sandwiching HgTe between CdTe. Is the CdTe really necessary? Would Vacuum/HgTe/Vacuum ...
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3answers
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Producing electricity from all wavelengths of electromagnetic spectrum
Is it possible to produce electricity from all wavelengths of electromagnetic spectrum beside visible light ?Like using gamma rays or x-rays .
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1answer
85 views
What is the difference between contact-limited and space-charge-limited charge transport?
I am reading a paper ("Tunable Electrical Conductivity of Individual Graphene Oxide Sheets Reduced at 'Low' Temperatures," Jung, et al. Nano Lett. 2008, 8, 4283-4287) about electrical conductivity in ...
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1answer
832 views
How to determine divergence of a LED source from a single biconvex lens
I'm trying to determine the divergence angle of light from a single lens that is completely illuminated by a high power LED.
Most optics textbooks only deal with imaging optics and I'm having a hard ...
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2answers
189 views
Mobility in semiconductors
Good afternoon everybody.
I am reading on a book about semiconductor mobility. I have fully understood the definition, but I also noticed that often one talks about high or low mobility. My question ...
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1answer
458 views
How is contact resistivity defined for a Schottky contact, or the Schottky barrier height for an ohmic contact?
Based on the transfer length method (TLM), one can accurately calculate the contact resistivity for an ohmic contact, by evaluating the absolute resistance measured through the test structure and ...
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1answer
56 views
In solar cells, do photons break apart electron-hole pairs, or create them?
Some sources say that when a photon hits the PV cell, it breaks apart electron-hole pairs. Other sources say that photons create electron-hole pairs. Can anyone explain which one is right? I've read ...
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2answers
210 views
Working of a p-n junction diode when forward biased
If p-type semiconductor and n-type semiconductor of a diode are equally doped, and if the diode is forward biased, then holes will move toward the n-type semiconductor and electrons will move toward ...
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1answer
340 views
What does the Fermi Energy really signify in a Semiconductor?
In understanding the behavior of semiconductors, I'm coming across a description of the Fermi Energy here and at Wikipedia's page (Fermi Energy, Fermi Level). If I understand correctly, the Fermi ...
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1answer
153 views
Momentum and indirect bandgap
When an electron is excited from valence band to conduction band, it has to have a finite momentum in the case of indirect bandgap. Does that mean that the electron cannot be created at rest ? does it ...
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1answer
291 views
Band offset and strain-induced valence band splitting in semiconductor compounds
My aim is to draw a plot of $GaAs_{1-x}Sb_{x}$/InP (GaAsSb on InP substrate) band offset as a function of As/Sb composition.
The first part is easy if I'm doing this correctly: I found VBO (valence ...
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60 views
How did the Bardeen-Brattain point-contact transistor work?
How did the Bardeen-Brattain point-contact transistor work?
What are the conditions under which a Schottky barrier injects minority carriers?
In a bipolar junction transistor the forward-biased ...
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64 views
Electron Relaxation/Polarization for and n-type Semiconductor
Please help me understand the following (general) statement, referring to electrons in a full valence band of an n-type semiconductor:
"An electron filling up the last empty state in the valence band ...
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Why does silicon have an indirect gap?
Is there an intuitive explanation as to why silicon has an indirect gap? I have heard that this can explained using pseudopotentials.
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Semi-conductors and induced charge
Can a semi-conductor ( germanium or silicon) or a semi-metal ( graphite ) carry an induced charge ?
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Solving a system of PDE equation in mathematica using a steady-state and time-evolution method [closed]
I'm working to solve the steady-state short circuit current of a solar cells, using the coupled continuity equations with a drift-diffusion expression and Poisson's equation:
...
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204 views
What is effective mass approximation
Currently i am studing about quantum confinement in semiconductors and came across effective mass approximation.but i am unable to understand this concept. what is the use of effective mass ...
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0answers
100 views
Problems in the modern semiconductor/electronics technology?
From what I have read, the problem with modern semiconductors/electronics seems to be quantum tunnelling and heat. The root of these problems is the size of the devices. The electrons are leaking out, ...
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732 views
Fermi-Energy Level for Extrinsic Semiconductor
How to change the Fermi-Energy level for extrinsic Semiconductor with the temperature change?
Thanks,
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1answer
112 views
Semiconductors and localization of the electrons
When looking at the band diagram of a semi-conductor, direct conclusion of the invariance under discrete translations, for a filled state with an electron, one does know precisely it's momentum, so my ...
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3answers
468 views
Why does a semiconductor hole have a mass?
I have read that holes in semiconductor are nothing but vacancies created by electrons. But how can this vacancy i.e. hole has a mass?
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1answer
44 views
Why is spectral sensivity of a photodiode expressed in A/W
Can someone explain me the meaning of the A/W unit of the photosensivity when reading a spectral response function of the wavelength characteristic of a photodiode?
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2answers
92 views
How local is the stress tensor?
I am confused by the definition of the stress tensor in a crystal (let's say a semi-conductor), I don't see how it could be "more local" than over an unit cell. I know that in field theory the stress ...
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230 views
Why should the Fermi level of a n-doped semiconductor be below the one of a p-doped?
In a pn-junction, the difference in Fermi level between the p doped and the n doped regions causes the apparition of a built-in electric field at equilibrium. This electric field goes from the n to ...
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2answers
2k views
How to make a single crystal silicon wafer?
How can I make a single crystal silicon wafer? What are the tools needed? What is the most diffcult part? Can I make it at home or at school lab?
I am now interested on Czochralski process where you ...
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2answers
179 views
Tunneling v. Hopping
Can someone explain the difference between hopping and tunneling? The context I'm considering is conduction in semiconductors, specifically between impurity states within the bandgap. It's always ...
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1answer
104 views
Semi-conductor band-gap and deformation potential
Submitting a semi-conductor to stress leads to a deformation in the energy-bands, roughly described by:$$H_{ij} = {\cal{D}}_{ij}^{\alpha\beta}\;\epsilon_{\alpha\beta}$$
$\epsilon$ being the strain ...
