Questions tagged [solid-state-devices]

Refers to solid devices built on silicon wafers or ceramic substrate. Materials used could be silicon, germanium or gallium arsenide with copper conductors and oxide based insulators. Doping is the addition of performance enhancements compounds such as gold or germanium. Includes transistors of all types and logic, analog and special purpose devices such as CCD sensors. When done devices are sealed with plastic or ceramic compounds.

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Potential distribution in MOSFET

Let us assume that an NMOSFET has its source, drain and substrate grounded therefore VDS and VSB=0 V . We apply a gate voltage VGS=2 V and I want to know how this potential is distributed as we move ...
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Trouble with body effect physics

I’m struggling to understand why a negative voltage applied to the bulk contact of an n-type MOSFET increases the threshold voltage. I read other similar questions and I get that the negative voltage ...
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Calculating capacitance in a MOS capacitor

A \$MOS\$ capacitor with \$t_{ox}=10nm\$ has an \$n^{+}\$ polysilicon gate electrode and an \$n\$-type substrate with doping concentration \$ N_D=10^{15}/cm^3\$ . Given: \$V_T=kT/q=26mV\$, \$\...
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-1 votes
2 answers
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Is it possible for an SoC to have a built-in SSD?

Is it possible to have an SoC that includes an SSD on-chip, or are there technical constraints that prevent that? What are those technical constraints, if any?
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MOS Capacitor band diagram question

In a MOS system, is the energy offset between metal/oxide or semiconductor/oxide always the same regardless of the gate voltage applied? In other words, are A and B in the diagram above always the ...
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1 answer
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Energy band diagram of a polar material

For a single piece of a polar material (ex. GaN, AlN, etc), there exists a constant electric field inside the material due to the bound charges at the surface. Above figure shows the resulting band ...
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2 votes
1 answer
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How to power this RF microwave solid state switch

I have the following RF switch: After googling for several hours, I have found that it is a solid state switch, from DC to 26.5GHz. I've also been able to test that between the golden plated female ...
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2 votes
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Why does the majority carrier concentration near the junction not decrease under forward bias? (PN junction)

We see that the current due to the majority carrier decreases near the junction as shown above, which means the majority carrier concentration should also decrease since the diffusion current is given ...
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4 votes
2 answers
649 views

Why are quasi-Fermi levels flat across the depletion region in a pn diode under forward bias?

Why is the quasi-Fermi level flat across the depletion region in a pn diode under forward bias? I get that EFn decreases on the p-type side and EFp decreases on the n-type side due to recombination, ...
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59 views

Secondary Coil Malfunction in an SSTC Circuit

I’ve designed an SSTC circuit which is based on a different topology and I wanted to accomplish it in real life. The circuit is operating at approximately 1.5 MHz during resonance and inherently, the ...
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1 answer
164 views

Derivation of microscopic Ohm's law from macroscopic version?

What I tried was: $$\overrightarrow{E}= - \triangledown V \qquad \qquad\qquad\qquad (1) $$ $$V= IR\qquad \qquad\qquad\qquad\text{(Ohm's law for materials where V}\propto \text{I)}$$ $$\text{...
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Given a energy band diagram, can you always calculate potential, electric field, and charge distribution?

Given a band diagram, where do you start to get the electric field and charge distribution?
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Electric field of Schottky diode

Reference: Device Electronics for Integrated Circuits 3rd Ed. Richard Muller I am trying to understand how to calculate the maximum electric field. The answer given in the book is $$E_{max} = \frac{-q ...
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1 answer
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Why does the value of shunt resistor need to be very high for solar cell's greater efficiency?

In the circuit equivalent of a solar cell, shunt resistor is described as "The irregular polycrystalline lattice grain boundaries that resist to the flow of electrical current in the silicon ...
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1 answer
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Solid state relay

How to connect a solid-state relay to an output MOSFET, which has 2 drain pins without the ground which I am refering to the image in the attachment? https://www.mouser.de/ProductDetail/Toshiba/...
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1 vote
1 answer
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Why does channel length modulation only occur in the saturation region?

As drain voltage is increased, the reverse bias across the drain-body junction also increases and thus the width of the junction should also increase which should deplete the channel length as well. ...
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2 votes
1 answer
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Is saturation region defined for a "given" collector emitter voltage?

I have seen the traditonal saturation regions graphs (attached). The graph gives the impression that there is a huge region which is saturation region. Shouln't the saturation region be for a "...
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3 answers
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Does the collector voltage have to be greater than the emitter voltage by few tenths of a volt for an NPN transitor

For an NPN transistor, does the collector voltage have to be greater than the emitter voltage by few tenths of a volt for it to be in active state? If yes what is the reason? Also it says greater by a ...
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0 answers
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How does the stored charge gets decayed when going from forward bias to zero bias?

In a pn junction diode when forward biased, excess electrons and holes get stored in p and n regions respectively. If we short the diode by connecting p,n terminals with a wire, how do these stored ...
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Relation between forward bias and current in a diode

I have seen the VI graph to depict the relationship between forward bias and current. (left graph) and I think I get it. I have also seen another graph (right graph) to depict the relation between ...
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How can a Zener diode maintain a constant voltage?

A Zener diode in reverse bias more than breakdown starts conducting. If you increase the reverse bias: It conducts more i.e current in it increases The voltage across it remains same I think I get ...
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2 votes
1 answer
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What is the exact meaning of 0.7V voltage drop in a forward-biased diode?

this question is partially (but not totally) discussed here: Why do diodes have a voltage drop? Does the power drop on a diode become entirely heat? The conclusion is that, in a forward-biased diode ...
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1 answer
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How to convert spontaneous emission into stimulated?

I have a semiconductor diode that has spontaneous emission (LED). The question is what can I change in the fabrication of the diode to improve its performance such that the diode gains a stimulated ...
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2 votes
0 answers
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Trying to Identify Static or Thermal Transfer Tape

I came accross this solidstate drive which is in a custom plasic and metal enclosure. There is a sheet of material cut out between the metal top and the drive. I'm trying to figure out what it is, it'...
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MOSFET current at very low temperature (4K)

I am trying to model the current at low T. To do so I need to compute the integral between the fermid diract statistic and the conductivity, with respect to energy. My problem is that I cannot ...
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1 answer
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Replacing X-ray or any radiation generating vacuum tubes with solid-state alternatives? [duplicate]

What are the reasons X-ray vacuum tubes could not be replaced by solid state alternatives? I'm thinking if it is possible to make a compact solid-state X-ray or higher energy photons generator just ...
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2 votes
3 answers
248 views

Why most particle accelerators used vacuum diodes instead of transistors?

HERMES III (High Energy Radiaton Megavolt Electron Source) at the Sandia at Sandia National Laboratories is the world's most powerful gamma ray generator. HERMES-III produces a highly energetic beam ...
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6 votes
3 answers
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Amplifiers without vacuum tubes or transistors?

Are there amplifiers that can work without vacuum tubes or transistors? Is it possible to create a working amp with high power without vacuum tubes or transistors?
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1 answer
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Purely Solid-State Circuit Withstanding 1kV, able to source 125mA

I'm looking to design a purely solid-state circuit that can perform the following: Handle an AC Source with Vpk=1kV and act like an open circuit. (Schematic 1) When the source is removed and replaced ...
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What is the structure of GaAs?

Ga has three valence electron, and As has five valence electron. How do they share electrons so that each has 8 valence electrons? Does each Ga atom share 5 electrons with 5 different As atoms?
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1 vote
1 answer
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Does hole concentration fall below the intrinsic concentration, if Si is doped with pentavalent impurities?

If we increase N type doping in a pure Silicon then according to the equation $$P_n=\frac{n_i^2}{N_D}\text.$$ Then mathematically, hole concentration is less than \$n_i\$, if \$N_D>n_i\$. Why does ...
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-1 votes
1 answer
137 views

What protective device can be used to avoid no-load operation in a dc series motor? [closed]

I think there must be some relay or converter which automatically shuts the machine on no load condition. ( Just Guessing ) The following para is a quora answer which I am not sure is correct, please ...
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direction of current densities for electrons and holes?

Let's say we have: \$ J_n = 3 \frac{A}{m^2} \$ and \$ J_p = 2 \frac{A}{m^2} \$ and let's define the direction of positive current (flow of positive charges) to be moving from left to right. Then, ...
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-1 votes
1 answer
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Does solar cell absorb sub-bandgap photons?

My understanding is that although we are taught that solar cells only absorb photons of energy higher than the bandgap of the material, some of the sub-bandgap photons still gets absorbed, which is ...
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0 votes
1 answer
119 views

Dielectric constant (relative permittivity)

I recently learned that the dielectric constant (or relative permitivity) is not actually a constant, but it depends on wavelength or frequency (dielectric function). If that is the case, why are we ...
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1 vote
1 answer
100 views

Does the Shockley Ideal diode equation involve drift current?

I've encountered a contradiction in semiconductors. The ideal diode equation considers saturation current (the current when applied voltage is reverse biased to the diode). I thought that saturation ...
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1 vote
0 answers
148 views

Semiconductor mass action law question

I was told that the mass action law $$np = n_i^2$$ only applies to compensated semiconductors and intrinsic semiconductors, and it does not apply to n-type or p-type semiconductors. Is this true? I ...
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1 vote
2 answers
73 views

IC Supply Current vs Temperature at low temperature

Background I am designing a low power device where every uA counts. It has a temperature range from -25C - 35C. In the datasheet for the 74AHC1G66; 74AHCT1G66, an analog switch I'm looking at, on ...
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Can anyone properly explain me the characteristic curve of the p-type JFET?

I know how a MOSFET works. But recently I wanted to know details about JFET. When V(GS) = 0 volts there will obviously a current flowing through the p-type channel. What confuses me is how the ...
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Forward Converter Snubbing Optimization/Alternative

I'm working on a single-switch forward converter with a reset winding and synchronous operation. The basic specifications are as follows: 12.0 +- 5% V output voltage 22-36 V input voltage 96 W / 8 A ...
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Short Channel MOSFET model

I was reading on a book (Thomas Lee, The Design of CMOS Radio Frequency Integrated Circuits) that in a short channel model, since the phenomenon of drift speed saturation is very relevant, it is a ...
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Why is the absorption coefficient (α) not zero for energy of incident photon less than the band gap of the semiconductor?

α ( Absorption Coefficient) tells us about the absorption of a photon by a semiconductor for the creation of electron-hole pairs. The absorption coefficient increases abnormally as the energy of ...
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-3 votes
1 answer
96 views

What is the scope of semiconductor device fabrication compared to other fields? [closed]

I am planning on applying to colleges for pursuing an MS degree. I would like to know the scope of semiconductor device modelling, both in terms of jobs as well as research. I also wish to know about ...
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1 vote
0 answers
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How does a FinFET reduce subthreshold swing comparing to a regular MOSFET?

I get that a lower subthreshold swing means there is a smaller current when the transistor is off and that's one of the reasons that finFET is preffered to MOSFET. But I don't understand how it does ...
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7 votes
4 answers
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Why datecode is SO IMPORTANT to chip manufacturers?

With the miniaturization of the devices, chip marking has shrunk, not only in size, but also in content. And while the part number got compressed to as little as two letters (or in some cases ...
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1 vote
1 answer
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Thermal generation of electron-hole couples and reverse biasing

I'm studying the PN junction and I have some problems figuring out thermal generation of couples electron-hole in reverse biasing. The analysis is the standard one (for example, one can find it in the ...
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2 votes
2 answers
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BJT: why does Ic increase when temperature increases? [closed]

When the temperature of an BJT increases, the thermal voltage $$ V_T = \frac{k_BT}{q} $$ where \$k_B\$ is the Boltzmann constant, \$T\$ is the absolute temperature of the junction, \$q\$ is the ...
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1 vote
2 answers
88 views

On what inherent parameters does the speed of mosfet depend in a SRAM cell circuit?

I want to design 3D IC with 2 stages for a simple SRAM cell. Some of the MOSFETs will be on the top stage while some on the bottom stage. The MOSFETs on the top stage are supposed to be degraded in ...
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0 votes
1 answer
175 views

So why do SSD disks have a reputation for power efficiency?

Why do SSD disks have a reputation for power efficiency? I've just looked at some the spec sheets for SSD and mechanical hard disks. In a lot of cases, the even during idle state, SSDs use slightly ...
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3 votes
0 answers
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High frequency switching applications

I was reading that for high frequency switching applications with semiconductors, the ratio of the electron to hole mobility should be high. Why is it so? Is it a necessary condition always? Or ...
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