All Questions
Tagged with semiconductors solid-state-devices
62
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27
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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, ...
- 447
-1
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1
answer
87
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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 ...
- 447
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266
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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 ...
- 447
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158
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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 ...
- 925
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246
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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 ...
- 447
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47
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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 ...
- 2,519
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43
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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 ...
- 3,550
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215
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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 ...
- 35
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135
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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 ...
- 171
1
vote
2
answers
449
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Why conductivity increases in semiconductor when doped?
I know it depends upon the concentration of electrons and holes . So if we add donor atoms, even though electron concentration in conduction band increases , hole concentration decreases due to more ...
- 469
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136
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Why in semiconductor studies, we are only concerned with reduced zone representation of e-k diagram?
Does electron transition from conduction band to valence band takes place only in first Brillouin zone? Or can it happen in any other Brillouin zone?
- 469
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215
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Why carriers move when Electric field is applied on Haynes-Shockley experiment
I would like to know why excess carriers/minority move when an electric field is applied at the Haynes-Shockley expirement
2
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1
answer
605
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Confusing regarding measuring barrier potential of a pn junction using a voltmeter
I have been trying to understand why we can't measure the Barrier potential existing in an unbiased pn diode but on seeing the answers I am quite confused.
There seems to be two answers to this ...
- 469
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votes
1
answer
115
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on-state voltage
I am trying to study an ever-on IGBT. in other words, IGBT is tried to be on in a long time. To this purpose, a +15V constant dc voltage is applied to the gate-emitter. But, when connecting a +2V ...
- 49
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345
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MOS Capacitor Band Edges
I am trying to understand the MOS-Capacitor band edge shapes. When negative voltage is applied for gate, why does the band edge across the insulator shift upward (and linear decreasing band edge)? ...
