# All Questions

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1answer
29 views

### Question about the purpose of a transistor [closed]

I've been studying about diodes and transistors and something made me wonder about the purpose of transistors. In the examples we were talking about increasing current by using two batteries with a ...
0answers
40 views

### At null temperature (0 Kelvin), is the current going through a diode (PN junction) null?

At null temperature (0 Kelvin), is the current going through a diode (PN junction) is null, for a positive voltage in a direct polarisation, above the built-in voltage of the depleted region ? If ...
1answer
51 views

### How does the $I$-$V$ curve for bulk metal look like?

For semiconductors, the current (I) vs. voltage (V) relationship is as shown in the picture below. As we increase the applied voltage, the electron-hole pairs generate increases too, so we see an ...
1answer
45 views

### Under which condition the drift velocity stops increasing proportionally with respect to the electric field

Our professor asked us a question the other day but i wasn't able to figure it out. If we increasing Electric field then drift velocity will increase, Because of this Equation: Vd = μ * E But at ...
1answer
269 views

### How does base-emitter voltage affect the current gain of a transistor?

I'm doing a Physics project related to transistor operation. My data shows that as the base-emitter voltage drop increases, the current gain of the transistor rises and eventually plateaus at a ...
1answer
52 views

### Specifics of the current flow in a tunnel diode

Those are two diagrams depicting current flow along with equivalent band diagrams form two different textbooks. I believe one first one is resonant diode and second is tunnel diode only. From the ...
1answer
31 views

### Is there twice the amount of current in semiconductors than that in conductors (at same temp.)?

In semiconductors unlike conductors where $e^-$ move from lower quantum states to higher quantum states in conduction band, electrons move from Valence Band to CB and create 'holes'. These holes add ...
2answers
60 views

### Current in semidconductors

I'm confused as to why when we measure current in an intrinsic semiconductor we calculate the summation of the current due to holes and that due to electrons as opposed to what's done in conductors. ...
0answers
46 views

### Resistance and Voltage [closed]

I understand that superconductors have zero resistance, but with zero resistance there should be no voltage right? because V=IR Also, why do diodes have such high resistance but no voltage in the ...
1answer
94 views

### Why is the emitter current of a common emitter slightly greater than the collector current?

I'm trying understand where electricians came to agreement that Ie = Ib + Ic. I know that the base of a NPN transistor is very thin, allowing electrons to flow through to the collector which explains ...
2answers
1k views

### Why does current have to flow in the same direction?

If current is just the movement of charged particles, why do the all have to move in the same direction? For example, if you reverse-bias a diode (connect the positive terminal to the n-type side ...
2answers
363 views

### Can diffusion current occur in conductors?

The question is quite simple. Can diffusion current occur in conductors like they're found PN-junction semiconductors due to concentration gradient? I need to see a rigorous description. Is there any ...
1answer
244 views

### Electrons Boiled Off At Cathode In Vacuum-Tube Diodes

This is my first time asking a question on this forum so I hope my question wouldn't violate any policies. Thank you in advanced for your help. I have been trying to learn about the vacuum-tube ...
1answer
5k views

### What is recombination current?

This term is used frequently to describe the mechanism of current flow in a forward biased PN junction. It is called "recombination current", where recombination is the process of conduction electrons ...
1answer
635 views

### Does ambipolar transport when an electric field is applied to the semiconductor imply zero drift current?

I am reading Neaman's book on semiconductor physics and devices and one of the more important conclusions are that excess holes and electrons drift and diffuse together due to internal electric fields....
3answers
238 views

### Do molten semiconductors conduct electricity better than solid semiconductors?

I read that electrical conductivity goes up as semiconductors rise in temperature as opposed to metals that lose electrical conductivity as temperature rises. Would semiconductors continue to conduct ...
7answers
2k views

### Why the electrons below the Fermi level do not conduct electricity?

Physically, why is it that the electrons need to excited above the Fermi level to conduct electricity? In other words, why is the current zero when the electrons lie below the Fermi level? Does Pauli ...
2answers
465 views

### Diffusion current in semiconductor while applying an electric field

In case of intrinsic semiconductor, while applying an electric field, only drift current should exist, right? As diffusion current is due to concentration gradient. So the electron flow will be ...
2answers
1k views

### Electron holes in metals

For semiconductors, conductivity is given by $$\sigma=n|e|\mu_e+p|e|\mu_h$$ where $\sigma$ is conductivity, $n$ is the concentration of electrons, $e$ is the elementary charge, $p$ is the ...
1answer
113 views

### What is a Shockley-Read current?

What is a Shockley-Read current? Googling it brings up nothing. Is it possible this is some obscure name for a type of diode current? I know what the Shockley-Read-Hall process is, is it related to ...
4answers
573 views

### Applying a voltage to a homogeneous semiconductor

Imagine that there is a homogeneous semiconductor (either a p-type or an n-type, but just one of them) uniformly doped. There is no diffusion current because of the uniform dopage, and there is no ...
1answer
362 views

### How SPAD work over Break Down voltage?

SPAD (Single Photon Avalanche Detector) works beyond Breakdown Voltage which is mentioned as Geiger Mode. But how this actually working. When bias voltage aceede breakdown voltage, generally high ...
1answer
338 views

### Error in current voltage relation? [closed]

The current voltage relation of diode is given by I=(e^(1000V/t)-1)mA,where the applied voltage V is in volts and the temprature T is in degree Kelvin. If I made an error measuring +-0.01 V while ...
2answers
94 views

### Semi conductors (holes and electrons)

The following relation is mentioned in my text book for semiconductors in thermal equilibrium. $$n_e ×n_h = n_i^2$$ $n_e$ stands for the number of electrons. $n_h$ stands for the number of holes. ...
1answer
28 views

### 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 ...
1answer
2k views

### Why does overclocking a CPU cause it to generate more heat?

It seems odd to me that overclocking a CPU causes it to consume more energy. The amount of energy flowing through the CPU should be related to the average number of 'gates' (or transistors) that ...