# Questions tagged [semiconductors]

Most generally a class of materials that are neither insulators or conductors in their natural state but which can be manipulated via doping or electric fields to change the conduction state. Silicon, Germanium, GaAs are some usual materials. The term is also used to speak about devices that are made from such materials. For example a processor from Intel can be called a semiconductor.

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### Is there any specific application for an indirect band gap semiconductor?

I know that direct band gap semiconductors are very attractive for optical emission, and even though indirect band gap are used as well, I keep wondering: is there any technology that specifically ...
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### How to calculate the total power of a LED using solid angle?

I have a LED with the max power of 130mW/sr and an opening angle of +-10° (so approx. around 20°). I conducted an experiment using this LED, the LED shines light to an un-doped silicon semiconductor ...
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### Has any implementation succeeded to have shared key inside chipset and protect it from exploits?

Since there is a lot of demonstration like using SEM (Scanning Electron Microscope) to read bits from ROM through the scanned image of chipset, is there any implementation that has managed to succeed ...
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### MOSFET gate substrate voltage

In a MOSFET the channel is formed between gate and the body it would sense to use gate body voltage to form the channel. Why is gate source voltage used to form the channel?
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### Designing BJT that's beta value is 120

I want to design a BJT that's beta value is 120 Following this picture can I say that the components of the base current are like this? J(B) = J(pE) + J(R) + J(RB) - J(G) - J(pC0) I want to design ...
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### (Too?) simple model of a pn junction

I want to build a simple model of a pn junction in order to show high school students how it works. I am not looking for something precise, so I use really simple discretization and I discard units. I ...
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### Solar cell DIY with monocrystalline silicon wafer

I would like to make my own solar cell- From a quick search on youtube, these 2 videos are apparently always the #1 result for "solar cell diy" keyword or similar: Video 1 Video 2 The ...
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### IGBT modelling from datasheet

how to model igbt from the APT150GN120J datasheet. ...
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### Mobility of electrons vs holes in semiconductors (intrinsic vs extrinsic)

I was reading my class notes and it was written that electrons are more mobile than holes because the effective mass of electrons are lower than that of holes. (μ=eτ/m*) I checked online to find the ...
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### Calculation of Rated Power for IGBT Module

For an IGBT module with the following characteristics, how can we calculate the rated power? I mean how much is the rated power for this module?
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### How can you measure voltage differences less than thermal voltage (~26mV at room temp)?

If thermal voltage is the average voltage of any given electron relative to the voltage at ground state, and this presumably fluctuates, how can you make any measurement on a circuit more accurate ...
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### Unknown logo on FGS25N120ANTD IGBTs. Which semiconductor manufacturer is this?

I bought 5 FGS25N120ANTD IGBTs from my local vendor a while back. I was unable to identify the manufacturer, based on the logo. Can somebody help me out?
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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 ...
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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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### IGBT chip metalization

Consider an IGBT chip within a power module. The top surface of the chip is often metalized by aluminum (with approximately 5 microns thickness) to bond some aluminum wires into the chip; I am hazy ...
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### What happens if doping concentration is less than Intrinsic concentration? Will the semiconductor act as intrinsic or extrinsic? Please Explain

Si has intrinsic conc of 1.08*10^10 If it is doped with conc less than intrinsic concentration what happens
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### BJT transistor working and construction

Why is electron concentration zero at collector side of the base in BJT transistor? And if electron concentration decreases with distance and becomes zero at the end base region how can it produce ...
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### Single Crystal Growing and Orientation (Silicon) using Czochralski Process

I'm working on small bibliographic research on photovoltaic panels, and I have chemistry background. I have confusion on crystallization (Czochralski method) imposed by the seed and following specific ...
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### Identity and advice on replacement of SM diode

I have a Sonos Play:3, which is past its warranty. I dismantled it to find it has the well documented fault with a blown capacitor. However, there is also damage also to one of the surface mount ...
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### Diodes when voltage is applied

Does the hole injection take place from p semiconductor to n semiconductor in a pn junction diode? Or it takes place only in the case of a transistor?
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### Failures on underside layers of a chip in IGBT power modules

Does somebody know how I can detect a layer of IGBT modules in which a thermal failure, e.g., voids, cracks, delaminations of solder joints, has taken place? We know there is fatigue in both solder ...
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### Can you buy Aluminum Nitride transistors?

We all know wide bandgap semiconductors, currently galium nitride and silicon carbide are the superstars becose many companies make them at relatively reasonable price. They aren't just mere lab ...
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### Peltier Module constant time and thermal Load

Hi everyone I am new to this forum. I am doing a project where I need to control one of the sides temperature of a Peltier device against human skin. So one side is in contact with the skin, and the ...
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### Discerning between transistor types

How do you tell different semiconductors (mainly transistors, sometimes even voltage regulator ICs, etc.) apart? Do they all basically look the same; or are there visual clues to indicate a certain ...
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### What kinds of semiconductors are used for high voltage devices?

IIRC, gallium nitride is one of them. But what about silicon? What do they use for making thyristor valves found in High Voltage Direct Current power stations?
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### What does the channel voltage in a MOSFET really mean and how does it lead to the Fermi level splitting shown?

Many books (Chenming-Hu Ch.6 Page 15, Neamen Page 413) use the term 'channel voltage' $V(y)$ to mean 'the potential in the inverted channel at a point $y$ distance away from the source along the ...
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### In this semi-ideal photodiode, what would be the physical interpretation of this current?

A real photodiode can be expressed as a circuit made of several ideal components, it looks something like this: simulate this circuit – Schematic created using CircuitLab I copied it from here ...
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### Why is the diode reverse biased in the determination of energy gap?

I know that the energy gap increases when we reverse bias the diode, but I still don't see why forward bias won't do the trick. How exactly does the width of the band gap matter in measuring it? A ...
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### Current density in an ideal pn junction diode

I found that the current density is as above. I am going really crazy with this problem as I can't get any clue from anywhere. I have been googling for 10 hours and have no idea. Please help. The ...
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### BJT NPN transistor

I am confused on a topic regarding NPN BJT transistors. When there is a collector-emitter voltage (VCE) applied to the NPN transistor (as shown in the figure) without a emitter-base voltage (VBE), it ...
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