Questions tagged [semiconductors]
Semiconductors are materials with electrical conduction between that of conductors and insulators.
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What is the difference between band gap and band edge in QDs or semiconductors?
I am studying AgInS2 quantum dots which are semiconductor nanoparticles. I obtain the absorbance spectrum using the spectrophotometer. in the spectrum, I observe a shoulder-like feature. It is common ...
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Can alkaline earth chalcogenides be doped with halogens for conductivity?
Which salts, of all the binary alkaline earth chalcogenides with a 'rock-salt' structure, can be doped with halogen anions replacing some of the chalcogen, without destroying the lattice? (That is not ...
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2D semiconductors, and their practical applications
I understand that there are many complications with 2D semiconductors!(1) However, I wanted to know whether there are any practical uses of 2D semiconductors in consumer products.
I tried searching ...
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Can someone help with GAMESS input files for heavy atom calculations (MoS2, WS2, etc.)?
I'm doing computational research on transition metal dichalcogenides for my chemistry class and I want to calculate a transition state optimization for the reaction $\ce{MoS2 +N^- -> MoSN + S^-}$. ...
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Conductive ink on silicon to bridge two isolated regions of the wafer
Can I use a thin layer of conductive ink on silicon to bridge two isolated regions of the wafer (p-type)? I know that using PVD methods would be the best option, but I don't have access to these ...
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Why is the local coupling constant (vibronic coupling) given in eV?
Should the local coupling constant g not be without a unit, as the Holstein Hamiltonian suggests?
$
H=\underbrace{\sum_{P, Q} h_{P Q}^{(0)} a_P^{\dagger} a_Q}_{\text{Fixed geometry}}+\underbrace{\sum_{...
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What is the net gain of charge carriers in a semiconductor if an atom is removed?
In pure germanium, all Ge atoms are bonded with a tetrahedral geometry. It has a band gap and is a semiconductor. If we remove one Ge atom, what type(s) and how many charge carriers will be generated? ...
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Why is the Einstein relation not valid for germanium?
In Elecronic Devices and Circuits, by J Millman and CC Halkias, it is written at one place:
.....coefficient of diffusion $D$ and mobility $\mu$ aren't independent. The relationship between them is ...
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Why Lambert's law does not hold for photoresistors?
Why don't photoresistors made of Si obey Lambert's cosine law? Is it related to the dark current of the photoresistor? I couldn't find any solution while searching the web.
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Advantage of Ir-based vs Alq3 OLED material, is quantum yield more important over the cost?
This Wikipedia page https://en.wikipedia.org/wiki/OLED#Material_technologies mentions a couple of molecules that are used for OLED.
The Ir-based compound has ~ 100% quantum efficiency, while Alq3 may ~...
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Why exactly is the conduction band in semiconductors conducting?
Is it because when the electrons are excited to a higher energy level, they can lose energy and fall back down to lower energy levels? Due to the sheer number of antibonding MOs in the conduction band,...
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Why is cuprous oxide a p-type semiconductor?
Wikipedia — Copper(I) oxide says $\ce{Cu2O}$ has semiconducting properties without any explanation.
Nolan [1] talks about $\ce{Cu^+}$ vacancies making copper(I) oxide an extrinsic p-type semiconductor,...
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Polythiophenes versus Polypyrroles
I've been searching for the differences in semiconductor properties of polythiophene (pth) and polypyrrole (pry).
Most resources just state their ability to form polarons and can be doped. However, I ...
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Bond formations in doping of semiconductors [duplicate]
I was reading about semiconductors and found out that semiconductors are doped with either 13th group or 15th group elements which are named p-type and n-type semiconductors, respectively. In n-type ...
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What makes up the conduction band?
Prologue/Rant about online classes
We have been taught the electron sea model to explain metallic bonding and conduction of electricity by metals. Then out of the blue, the band theory was introduced, ...
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Is the case of the linear chain of atoms one-dimensional?
I am currently studying Diode Lasers and Photonic Integrated Circuits, second edition, by Coldren, Corzine, and Mashanovitch. In chapter 1.2 ENERGY LEVELS AND BANDS IN SOLIDS, the authors say the ...
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What does "spin degeneracy" mean in this context?
I am currently studying Diode Lasers and Photonic Integrated Circuits, second edition, by Coldren, Corzine, and Masanovic. In chapter 1.2 ENERGY LEVELS AND BANDS IN SOLIDS, the authors say the ...
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Organic Based Photocathode
What organic molecules have a relatively small work function, preferably in the visible spectrum? Polycyclic aromatic hydrocarbons are in the low UV spectrum, making it unsuitable for the photocathode ...
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Quantum Internal Efficiency
I'm reviewing a homework problem where we're given a hypothetical organic semiconductor which has a fluorescence efficiency of $40$% and a phosphorescence efficiency of $60$%.
From theory, I know that,...
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Silicon–Boron Covalent Bond
This is a semiconductor-related question, but in order to understand the acceptor level energy state of boron in bilicon, I figured I'd ask here for hints.
Boron is a p-type material when introduced ...
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“Good” properties of transparent conducting oxides
I'm a computer scientist and I'm trying to figure out which are the key properties that define a “good” acting transparent conducting oxide (TCO) in order to consider several possible features to ...
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Photoluminescence Spectra of Solids
What information can we gain with the photoluminescence spectra of solids? The bandgap can be determined for example, but are there any other useful properties we can learn? I care about this in the ...
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Semiconductor Li-ion batteries
I have recently come across the concept of semiconductor Li-ion batters, for instance carbonised polyacenic semiconductor (PAS) Li-doped materials.
I am not sure how common it is for a battery to be ...
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Why is liquid germanium denser than solid germanium?
Why are some elements like Ge and Si have liquids denser than their solids? In water it is explainable by H bonding, but no H bonds or such are there in Ge and Si.
Well, I want an explanation about ...
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Difference between vapor-phase transport and vapor-phase deposition?
I am currently studying the textbook Physics of Photonics Devices, Second Edition, by Shun Lien Chuang. In a section discussing The Invention of Semiconductor Lasers, the author says the following:
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Importance of zinc blende and wurzite crystal structures for semiconductors?
I am currently studying the textbook Physics of Photonics Devices, Second Edition, by Shun Lien Chuang. In a section discussing the basic concepts of semiconductor band and bonding diagrams, the ...
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Reconciling electron configuration and valence electron distribution over separate energy levels in energy band theory [duplicate]
The electron configuration of a Silicon atom in its ground state is $\ce{1s^2 2s^2 2p^2 3s^2 3p^2}$, or equivalently, $\ce{[Ne] 3s^2 3p^2}$.
When looking at the energy-level scheme of a silicon atom, ...
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Would graphene be a good efficient conductor of electricity in mobile phones [duplicate]
Gold is commonly used in mobile phones as an electrical conductor,as it is apparently better than copper at conducting electricity
Quoting from extremetech.com :
"The materials recovered are reused ...
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Further reading on photoconductivity of hemoglobin
I recently ran into this paper which describe experiments that confirm that hemoglobin is photoconductive. Finding this fact as incredible, I wanted to read up more on photoconductive properties of ...
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Gamma spectrometry
I want to calculate minimum detectable activity (MDA) at 200 and 300 keV energy of a gamma spectrometry by HPGe detector. 662 keV Photopeak is present for 137Cs.
Assume 2 scenarios:
There is a 'peak'...
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What is the definition of a bipolaron and a dipolaron?
I wondered about the exact definition of a bipolaron? In particular, if I have an oxygen vacancy in a metal oxide and the 2 excess electrons (when forming a neutral oxygen vacancy) localise on the 2 ...
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What are the oxidation states of galium and arsenic in GaAs semiconductor?
According to the book I'm referring to ("S.M. Sze Semiconductor Devices"), gallium has an oxidation state of +1 and arsenic has that of -1. This should not be possible as each of these elements forms ...
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Why are silicon and germanium used as semiconductors but not other metalloids?
The semiconductor materials are either elementary such as silicon and germanium or compound such as gallium arsenide. Silicon is the most used semiconductor for discrete devices and integrated ...
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How to find out which organic molecules would be good electron acceptors/donors on a GaAs semiconductor surface [closed]
I'm a physicist in way over my head.
I have a list of organic molecules to investigate, all common aldehydes and amines. My supervisor wishes to know which of these molecules would be good electron ...
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NiO and ZnO electrical conductivity with oxygen pressure
NiO is a Mott-Hubbard insulator and increasing oxygen concentration leads to anion excess and oxidation of Nickel so electron hopping is more favourable so electron repulsion is reduced and it becomes ...
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How to tell the needed doping element for semiconductors?
I was reading about a crystal that is a semiconductor, galena. I am confused on how to tell what elements are needed to dope it to make a p or n type semiconductor, as well as how to know which ...
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Conductivity of a semiconductor at high temperatures
I understand that increasing the temperature of a semiconductor excites electrons in the valence band into the conduction band. Hence, the resistivity of a semiconductor decreases with temperature.
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How to determine mobility when two mechanisms exist simultaneously
Two scattering mechanisms exist in a semiconductor. If only the first
mechanism is present, the mobility will be $\pu{250 cm2/V s}$. If only the
second mechanism is present, the mobility will be $\...
user30545
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Conductivity of Wüstite
"Wüstite is often represented as $\ce{Fe_{1-x}O}$, where $x$ is some small fraction less than unity. In this nonstoichiometric $\ce{Fe_{1-x}O}$ material
conduction is electronic and the material ...
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Band alignment of heterojunctions
I have seen several band bending diagrams in journals and the web. However, I am not sure as to how they align them. Some diagram appear to align the vacuum level and some align them by Fermi Level. I ...
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Why is it important to minimize impurities when doping a semiconductor?
I was reading "Electronic Devices and Circuits" by Boylestad, and in there the author talks about how the semiconductor industry seeks to add as little impurities as possible when manufacturing ...
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Why does Ga improve conductivity of Ge?
This is for my AP Chemistry course and the question is:
Which of the following elements is important in the semiconductor industry to improve the conductivity of Ge?
K
Ga
Al
Mg
It seems like any of ...
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What is the limiting value of band gap that makes a material semiconductor?
What is the limiting value of band gap (in eV) that makes a material semiconductor? Or what is the value of band gap that separates insulator and semiconductor?
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Why does phosphorus give a free electron in silicon doping?
Extrinsic semiconductors are created by doping an intrinsic semiconductor; typically silicon is doped with phosphorus to create free electrons or boron to create "holes".
In the case of phosphorus ...
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What is a covalent semiconductor?
Aren't all semiconductors' atoms bond in a covalent bond? How is a "covalent semiconductor" different from other semiconductors?
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Is the photoelectric effect possible for semiconductors?
Is the photoelectric effect possible for semiconductors?
I imagine that this might be, if possible, a two-photon process: excitation of an electron from a filled to conductance band, and then on to ...
user7232
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Why is silicon used in computer chips?
Most computer chips contain or are made of silicon. Why silicon? Why not copper or tellurium or some such?
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What sort of molecules or polymers are used in OLED displays?
OLED displays have been emerging as competitors for LCD displays for some time and are now common in mobile phones (see comparison of a Google Nexus 1 and an iPhone here)
The displays use small ...
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Choice of doping elements in semiconductors
In a typical semiconducting material, we start with silicon (group IV) and introduce atoms of group V or group III depending on whether we are constructing an n- or p-type semiconductor respectively.
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