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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Type of energy in energy band diagram of a solid

What type of energy do the energy levels in the bar graph of a solid such as silicon (Si) represent? potential energy? kinetic energy? or total energy? I saw in a book that kinetic energy of an ...
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What is the relationship between Diode Junction Current and the Fermi-Dirac probability function?

The equation for the Fermi-Dirac distribution function is $$f(E)=\frac{1}{e^{(E−E_F)/k_BT}+1},$$ and can predict charge neutralization. How is this applied to a diode's junction current and can this ...
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Besides of photon, what else can excite electron from valence band to conduction band, then to form exciton?

The title is my question. Besides of photon, what else can excite electron from valence band to conduction band, then to form exciton? thank you.
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How to interpret XRD results?

I am given several datapoints of XRD strain information. It comes from XRD measurement of a thin layer (100 nm) of semiconductor deposited on top of another semiconductor. The result I'm given is ...
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What is Electromagnetic Cross Section? (shock section)

What is Electromagnetic Cross Section? (shock section) Hello, I have a question regarding the manufacturing process of electronic components in the case of the silicon deposition and corrosion process....
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Why does total internal reflection (TIR) drastically reduces the efficiency of LED?

Total internal reflection (TIR) is the primary reason of efficiency loss in LED bulbs. LED chips are made of GaN, which has a much higher refractive index than surrounding materials. Because photons ...
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Where is the excess energy going to when a solar inverter is operating a photovoltaic (PV) panel away from the maximum power point (MPP)?

The MPP is the maximum power point of a solar panel and a PV inverter will typically try to find this MPP to yield the maximum energy ouput. But sometimes it might be neccessary to operate the panel ...
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Why doesn't $\rm Cu_2O$ fluoresce when illuminated by light with energy greater than its band gap?

From my understanding of $\rm Cu_2O$, it is a direct band gap semiconductor. I would expect that the dominant recombination mechanism would be radiative recombination. As its band gap is 2.17eV, I ...
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Fraction of electrons that diffuse across pn junction?

Roughly how large fraction of the surplus electrons from the n-type doping will transfer across to the p-type material? Interested in just a rough estimate, is it closer to 1%, 50%, 100%?
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How to find the equation for $m^*_p$ (the effective mass of the hole) in solid state physics?

I'm having trouble finding the $m^*_p$ equation (effective mass of the hole). I know that the equation for $m^*_n$ (effective electron mass): Note, that following the guidance of the book, I managed ...
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Why is generation rate equal to recombination rate in extrinsic semicondcutor?

The mass action law states, that the product of electron concentration and hole concentration is equal to the square of the intrinsic carrier density. That applies to both intrinsic and extrinsic ...
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Is GaAs (100) surface polar?

I have a question on the GaAs surfaces. Depending on the crystal orientation, GaAs could be polar or non-polar. For example (111)B surfaces are terminated by the As atoms, whereas A surface is Ga-...
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Is a dye an indirect semiconductor if it looks black under monochromatic light that is of different colour?

I have noticed that most objects such as the red dye in a plastic stool look black under blue or green light. From what I understand about direct band gap semiconductors, the dominant recombination ...
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How can NO charge carriers exist in the depletion region?

I learned that no charge carriers exist in the depletion region of a PN junction due to the balance between the diffusion current and the drift current due to the electric field created by charged ...
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Unable to derive Grand Canonical Free energy for single electron transistor (SET)

I am try to derive the expression for Grand canonical free energy for single electron transistor (SET) and started with a simpler case as shown below from Physics of Nanoelectronics by Tero Heikkila: ...
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Why do AlAs and GaAs have the same lattice constant?

Is it related to the electron affinity of the AlAs being larger than GaAs?
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Understanding alpha and beta factors in transistors

I am a student and this is first time we are introduced to semiconductors. During studies I learned about the alpha and beta factor in a transistor. Actually I was doing some numericals were I got ...
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What could be the cause of a limit in the voltage supplied to a capacitor?

Recently I built a very basic 2-stage coil gun for a school project. Each coil was powered by an electrolytic capacitor. In order to charge the capacitor, the coil connected to an IGBT (insulated-gate ...
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How does the tuning of fermi energy/level in semiconductors via doping and other factors affect the semiconductor's performance or properties?

I was watching one of my lectures from my material science and engineering degree, and the lecturer mentioned by adjusting the doping and operating temperature of a semiconductor , the fermi level ...
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Why is Fermi energy considered most probable energy that electron posses in solids?

It can be seen in graph that probability of electron occupying a energy level below $E_{f}$ is $>\frac{1}{2}$, then why it is said that Fermi energy is considered as most probable energy that ...
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On current density calculation

Current density in semiconductors is often expressed as $$ \mathbf{\vec j}=\mathbf{\vec j}_n+\mathbf{\vec j}_h $$ where $\mathbf{\vec j}_n$ is the current density due to mobile electrons, and $\mathbf{...
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How does ambipolar transport work?

In my introductory semiconductor physics class, I learned that "excess holes and electrons move together in the presence of an applied electric field because of the development of an internal ...
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Reverse Bias PN-Junction/Diodes

In a revesed bias PN-Junction/Diode, the electrons are attracted to the positive terminal from the external power supply while the holes are attracted to the negative terminal, incrasing the depletion ...
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How the positively charged holes are created inside a p-type semiconductor?

To be more specific, we know that the holes are intentionally created via doping with some trivalent impurities (i.e Boron, indium, aluminum etc.) and We know that the holes are positively charged. ...
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Trouble understanding physics behind MOSFET body effect

I’m struggling to understand why a negative voltage applied to the bulk contact of an n-type MOSFET increases the threshold voltage. I can see why it happens due to the equations, but I can’t wrap my ...
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How to find hydrogen atoms concetration from a doping profile?

Hydrogen atoms passivate dopant atoms. I want to find hydrogen concentration from a calculated dopant profile for a p-type silicon Schottky junction. Does anyone know how to go about this?
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Why no acceptor energy level in pure semiconductor?

Why there is no acceptor energy level in pure semiconductor? (assume some holes are formed due to heat), While the holes created here to effectively conduct electricity , bonded electrons must ...
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What does it mean if the Fermi level crosses into the valence band? How about into the conduction band?

I've been working on this material to get more accustomed to Quantum Espresso, and I've gone on and performed calculations to get their band structures. Here are the band structures that I got for two ...
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EMF being equal through KVL

In the given figure,we connect three cells of different emf which are $V_1,V_2,V_3$ with a resistance $R$ in the first loop. Now suppose we emit current $I$ from $V_1$. $I$ gets divided into $I_1$ and ...
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Why can a non-Metalloid be a Semiconductor?

I was reading that the first description of a semiconductor material was made by Michael Faraday in 1833 and published in Experimental Researches in Electricity.-Fourth Series (https://www....
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Current in primary circuit when diode in secondary circuit is reverse biased

Let's say we have an ideal transformer with a diode in the secondary circuit: If the diode is reverse biased, there would be no current in the secondary circuit, which would mean that there is no ...
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What happens to the Fermi level of a metal/semiconductor under bias?

When a metal/semiconductor junction is placed under bias, the Fermi level of the semiconductor shifts horizontally up or down increasing or decreasing the potential barrier. I was wondering if this is ...
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Activation energy for Semiconductors

I was looking for a clear definition of the activation energy for semiconductors and I found that it is related to the generation of electron-holes pairs, but I didn't fully understand how the two are ...
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I’m trying to charge a capacitor. Would a bridge rectifier charge it like a battery would?

Since a bridge rectifier converts ac to dc. Will this charge my capacitor to max capacity how hooking it up to a battery would? The positive is charging the anode, while the cathode is grounded. Any ...
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Simulating microscopic interactions in semiconductors

My device physics book did not really reference QM and the simulation approach it gave basically amounted to solving a PDE under some assumptions in relation to charge flow, recombination/generation ...
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Can free electrons pass through the holes?

In crystalline silicon, when we say that free electrons can move until they fall into a hole, is it possible for that free electron to pass through the hole and continue to move?
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How do I calculate the standard uncertainty? Task on determination of energy gap width of semiconductors

I am creating a report for my physics class and all I have left to do is calculate the standard uncertainty for this formula. $$ \ln \left( \frac{R_{T}}{R_{\infty}} \right) = \ln \left( R_{T} \right) -...
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Spin conservation in indirect optical transitions in bilayer TMDC

While I was reading this paper (https://arxiv.org/abs/2108.09129), I got confused with the spin conservation in optical transitions in bilayer 2D semiconductors. In figure 3(d), indirect transition ...
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Questions regarding physical electronics [closed]

I ran into some questions while studying physical electronics. My textbook/lecture note says "An electric field applied to a semiconductor will produce a force on electrons and holes so that ...
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Why does the non-radiative lifetime in semiconductors decrease with an increase in temperature?

Came up in a lecture recently but I can't think of a reason why
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Donor and acceptor concentrations on a Si speciment

Suppose that we have a Si speciment and there are Ga atom impurities of $2*10^{16} \text{cm}^{-3} $. I was thinking, if we insert As atom impurities of $4*10^{16} \text{cm}^{-3}$ at the first half of ...
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What is the difference between ambipolar transport and excitons?

I know that ambipolar transport is the coupled motion of nonequilibrium electrons and holes to ensure that internal electric fields remain small. I also know that excitons are due to a bound state of ...
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How PIN (Positive Intrinsic Negative) junctions work? [closed]

Studying the operation of the photodetectors I came across the PIN (Positive Intrinsic Negative) junctions. Honestly, I have not found very clear material on the Internet. Exactly how do these PIN (...
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How does a photodetector work more specifically?

I’m studying how fiber-optic communication works. To transmit a signal, you need a transmitter that converts electrical impulses into luminous and a photodetector that performs the reverse operation. ...
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Is it possible to tune the band gap of silicon by mere doping?

I came to know that only the band gap of direct band gap semiconductors be tuned by doping and the band gap of indirect band gap semiconductor can't be tuned. How is it possible ? How is doping ...
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Electric fields and intrinsic semiconductors

If we apply a electric field to a conductor the charges inside move close or away from the electric field which creates a electric field inside the conductor which cancels out the external electric ...
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Terahertz generation in semiconductors after ultrafast laser excitation

Terahertz can be generated by means of the photo-Dember effect, where a short laser pulse generates electrons and holes. These charge carriers have a different mobility which gives rise to a dipole ...
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Allowed energy levels in an $E$-$k$ diagram

For a particle confined in an infinite potential well in 1D, the $k$ value is quantized as $k=nπ/a$, where $a$ is the length of the region where $V(x)=0$. However, the $E$-$k$ diagram derived from ...
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Why there is no current when diode ia reversed biased?

I try to understand why, really, there is no current (except for leakage) when a diode is reverse-biased. I studied several texts, and noone really explains, like for instance this otherwise very ...
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How can an $n=25$ Rydberg state exist in a solid? What does the wave function look like?

Phys.org's April 15, 2022 Ancient Namibian stone could hold key to future quantum computers begins: A special form of light made using an ancient Namibian gemstone could be the key to new light-based ...
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