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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Can we know the limit of the number of times information can be stored/retrieved in computer chips - hard disks and RAM? [migrated]

I was wondering whether the memory storage of a single memory area in computer semiconducotrs is limited in terms of the number of times we use and if I am at the edge of using it up, will it stop ...
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82 views

Why do we have Indirect bandgap semiconductor?

If the energy of an electron is proportional to square of the momentum k, how come we have a Indirect Bandgap material in which the minimum of the energy in conduction band is not at k not zero. P.S. ...
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8 views

Quasi-fermi levels in a solar cell?

I was wondering, if my fermi levels splits up due to n and p type doping into two fermi levels, one for the p type one for the n type, and now due to light radiation my fermi levels split up into 2 ...
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Bandlike vs. Excitonic Semiconductors

What is the different between 'bandlike' semiconductors and 'excitonic' semiconductors and how does this relate to whether they are organic or inorganic? I also wonder how such bandlike or excitonic ...
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121 views

Question about electron-hole pair generation in depletion layer for a p-n junction photodiode

At the heart of operation of p-n (or p-i-n) junction photodiodes is the absorption of photons leading to generation of electron-hole pairs. If the diode is, e.g., reverse biased, then the motion of ...
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What's the difference between semiconductor and insulator (besides band gap)?

The typical classification of electronic materials is metal-semiconductor-insulator. Is there any actual difference between a semiconductor and an insulator, besides the size of the bandgap?
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105 views

Does Saturation velocity in semiconductors have a relation with the wavelength in which the peak in the absorption spectrum occurs?

Saturation velocity is the maximum velocity a charge carrier in a semiconductor, generally an electron, attains in the presence of very high electric fields. (source) I want to know if the ...
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Books on Hall integrated circuit (IC)? [closed]

Can anyone suggest a good reading on Hall integrated circuit that is used in practicals on magnetism?
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Can I use an IV curve alone to differentiate between metallic, semiconducting and insulating materials?

Assuming the size of the bandgap is expressed as resistance in the IV curve, could I tell between metals, semiconductors an insulators by only doing an IV sweep? For example very high slopes (large ...
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Why do solar cells have a window layer on top of the absorber layer and not below it?

In solar cells there is a p-n junction. P-type semiconductor (for example CdTe) is often absorber layer because of its carrier lifetime and mobilities. In case of CdS/CdTe,* CdS is n-type window layer ...
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What is the difference between Rashba coupling effect and spin orbit coupling effect

We know standard spin-orbit coupling and spin Hall effect. But what is the differences in Rashba coupling effect? What changes in Rashba coupling effect?
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145 views

Is carrier charge density and carrier mobility constant in a given material?

If we assume the semi-conductor is doped by a variable amount, is there some way I can look up carrier charge density for the material in a reference somewhere? What about carrier mobility?
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What is a Fermi arc?

What is meant with a Fermi arc, for example, in the context of Weyl semimetals? Is this the just a one-dimensional Fermi surface? For example, in electron-doped graphene, the Fermi surface consists ...
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What would happen if an N doped semiconductor is connected to voltage?

I've been trying to learn electronics alone, and recently stumbled upon transistors. To my understanding, transistors are like two PN junctions back to back, but with the P region very thin. This ...
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40 views

Exciton in semi-conductor

I don't understand why an exciton describes only the interaction between an electron hole and an electron in the conduction band? How is this interaction different from the interaction between an ...
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211 views

Why is an exciton only observed when we excite to the conduction band and not to other electronic level inside the bandgap?

Excitons can be observed when we excite electrons to the conduction band. I don't know about excitons being observed when we excite the electrons to an electronic level that would eventually be in ...
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Transition Capacitance & Diffusion capacitance of a diode

What are Transition and Diffusion Capacitances of a Diode? Why is Transition capacitance more significant in the reverse bias condition? Why is Diffusion Capacitance more significant in the forward ...
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433 views

Semiconductor problem: how much Boron is required to establish a certain amount of charge carrier density

The problem description is as follows: Boron is used to dope 1 kg of germanium (Ge). How much boron (B) is required to establish a charge carrier density of 3.091 x 10^17 / cm^3. One mole of ...
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50 views

Fermi Level: chemical potential vs. electrochemical potential

In solid-state physics it is understood that the Fermi-Level is the electrochemical potential. The Fermi-Level is defined to: However, in thermodynamics this formula is referred to as the ...
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314 views

If we connect a block of p-type semiconductor only to a positive terminal, will it become positively charged?

Connect the positive terminal of a battery to a piece of p-doped semiconductor, say, silicon doped with boron. Will the terminal pull electrons out of the doped silicon, or equivalently, inject holes ...
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92 views

Internal Resistor in a Diode

When we talk about the resistance of a diode (of the P and N region), is this resistance like the one inside an Electro-Motive Force or it acts like a normal resistor (external electric field exist)? ...
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103 views

Effective masses for different direction

Assume we have an indirect semiconductor where the effective mass becomes anisotropic in different directions. Usually, one talks about a mass in parallel and perpendicular direction referring to ...
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Extremely forward biased pn junction

When a pn-junction (e.g. an LED) is forward biased the height of the potential barrier is reduced... ...unless you apply a huge potential $V$, in which case the barrier gets inverted and the band ...
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103 views

Electric Field inside a diode

When a voltage is applied to a diode (Forward or Reversed bias) the depletion zone is changed due to charges change in this region. My question is in both case (Forward or Reversed bias), how the ...
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Silver vs Aluminum electrodes in silicon solar cells?

In a typical high efficiency solar cell, silver is used as a front contact and aluminum as the rear contact. Despite the lower resistivity of silver, the usage of aluminum as a front contact would ...
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136 views

How can I simulate a model electronic hole?

Suppose I can solve time-dependent Schrödinger equation for several 1D particles (currently 3). I'd like to see, what an electronic hole is and how it behaves — in a series of numerical experiments. ...
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PMOS Gate Oxide Capacitance Equation? [migrated]

I'm having a hard time finding the correct equation for the question shown below. Any ideas on which one I'd need? I've seen this equation: I understand that $\varepsilon_{ox} = \varepsilon_r ...
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Doped PNP Bipolar Transistor [migrated]

When doping a PNP bipolar transistor, does it matter which parts are doped by what amount? The picture below will show my question. Am I right in saying that the Emitter is connected to one P region, ...
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114 views

Semiconductor band diagram with a doping gradient

What does the Energy band diagram in a semiconductor look like if we introduced a doping gradient? What would it look like if after we added the doping gradient we introduced an electric field? I ...
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314 views

Why is the law of the p-n junction valid under forward bias?

I'm currently studying the physics of the PN junction. I went though the derivation of the built-in potential in the PN junction under equilibrium: $$ {Diffusion\ current\ density} = {Drift\ current\ ...
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130 views

Are there measurable quantities which directly depends on the Fermi velocity?

The dispersion relation of electrons in, for example, graphene exhibits Dirac cones. The dispersion relation of a Dirac point at $\mathbf{k}=\mathbf{K}$ is linear in the momentum magnitude: $$E=\pm ...
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20 views

How can a phosphorous ion dope silicon when it is already ionized?

In ion implantation dopant ions are directly bombarded into the semiconductor (silicon for example)? But if say P ions (P+) were implanted then it does not have an extra electron to donate into the ...
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Working principle of CIGS solar cells

can anybody explain me how CIGS solar cells working.when photon hits the window layer is there any EHP created or ,that buffer layer lets pass photon energy to absorber layer.please explain me by ...
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CIGS Photo Voltaic cells

Why n type layer is on top of p type layer in CIGS solar cells? does it do anything with wavelength of photon and thickness of window and absorber layer?
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209 views

What factors cause the velocity saturation to occur at different electric fields for different materials?

In semiconductors the velocity of carriers gets saturated after a certain value of electric field. In silicon it occurs at around $10^4 kV/cm$ and in GaAs at some other value. What factors are ...
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24 views

Calculation of RMS current in half wave rectifier

While calculating RMS current in half wave rectifier, why we will consider only half wave that means only we consider the limits 0 to pi. But here RMS current is for AC input..so why don't we consider ...
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52 views

Tunnel diode/quantum tunneling

How does a tunnel diode work?/How does a tunnel diode use quantum tunneling, and how does quantum tunneling make the diode faster?
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Does doping and size determine the characteristics of a semi-conductor?

Does the maximum voltage and current that a semiconductor can withstand (without being damaged) depend upon the size and doping of the semiconductor? If so, then please explain, 1.What is the reason ...
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115 views

Why do silicon solar cells only produce ~0.6V when the band gap of silicon is ~1.1V?

I've been researching into this and can't quite figure out where that lost voltage is going. When silicon is excited by a photon within its absorption spectrum, it will always have an internal ...
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124 views

Why can solar cells be made of indirect and direct semiconductors? (Comparison between some pn-junction devices)

Various textbooks mention, but not go into detail, how semiconductor devices are optimized for their particular function. E-k space is trascendental to understand this, given that it depends on the ...
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What is the smallest possible electronic transistor?

Computers have increased in processing power mainly due to the miniaturization of transistors. I read recently that IBM, with great difficulty, shrank circuits from 14nm to 7nm but progress seems to ...
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Why the optical gap is not identical to the charge gap?

The optical gap is the photon energy required to create an exciton (in a solar cell for example). The charge gap (aka electrical gap) is the energy (voltage) required to create a photon (in an LED for ...
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98 views

How does a minority carrier diffuse?

I have gone through a lot of questions but none of them ask how do the minority carriers approach the depletion layer in the first place. When a p-n junction is formed, negative space charge ...
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229 views

In a positively biased PN junction, where do the injection carriers come from?

I am not quite understand i-v character of PN-junction diode. Here is the model in textbook. The PN junction diode can be divided into three regions. They are One depletion region near the PN ...
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43 views

What causes this IR emission in UV 365nm LED?

I've just got access to spectrometer and measuring spectrum of everything. But when I took a look at 365nm UV led from chinese UV flashlight I got something really strange - it had some IR at exactly ...
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Why is Fermi-Dirac type of distribution used in semiconductors?

We assume that distribution of electrons follows Fermi-Dirac distribution / statistics in semiconductor model which will help to find the concentrations of electron and holes and the relationship ...
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346 views

What are the differences between supperlattices and Multiple Quantum Wells Semiconductor Structures?

Semiconductor Optoelectronics: What are the differences between multiple Quantum Wells and supperlattices.
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Nature of photoluminescence at a semiconductor heterojunction

Do I understand it correctly that photoluminescence at a semiconductor heterojunction occurs because of intralayer recombination? If so, why can't photoluminescence occur because of interlayer ...
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Why do semiconductors remain neutral outside the depletion region?

Why there is a sharp cut off of the charged region outside the depletion region, like on this image? For example why don't electrons on the conduction band in the n-type side rush towards the ...
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Why does normal incidence eliminate the photocarrier effect radiation in this experiment?

Here's a paper in which they use GaAs crystals at a few orientations to produce THz radiation, by means of Optical Rectification (OR). That's actually not what this question is about, though. They ...