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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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Why does the current in MOSFET have a quadratic function (explain logically without using the integration method)?

The current equation relating Vds ,Vgs and Vt is already known to us ,but if there is any way we can find out how it varies quadratically without using the formulae?
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How does the hot point-probe test affect p-type semiconductors?

In an n-type semiconductor if you place a hot probe close to a cold metal probe, the average thermal velocity of electrons near the hot probe increases which leads to a net electron motion from the ...
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MOSFET switching on

I have a doubt. Consider an N-MOSFET: which is the voltage that can switch on it? The voltage between Gate and? Sometimes I read "between Gate and Bulk", sometimes "between Gate and Source", sometimes ...
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Why does the base-emitter voltage in NPN transistor become constant?

The setup above shows the experiment that I have been working with. During the experiment, the current \$i_c\$ and the voltage \$V_{be}\$ were measured for increasing \$V_{in}\$. At some point, the ...
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31 views

What does this ɣ constant relate to in the carrier motion of BJT

What does the constant ɣ represent in the following carrier motion of an PNP transistor? So I see three components for the base current. 1) According to the illustration I can see that some of the ...
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3answers
276 views

PN junction band gap - equal across all devices?

With a given material eg silicon, is the band gap constant across devices? For example, at a constant temperature is the band gap of a diode ("diode drop") exactly the same as that of (say) an NPN ...
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Estimating IGBT current density

An n channel NPT IGBT with a base width of \$0.101 mm\$ and doping \$10^{13} cm^{-3}\$ is to be trimmed to a maximum common base current gain of \$0.94\$. If the injected hole density at the edge of ...
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Maximum current for a turn off thyristor

A gate turn off thyristor \$\beta_{off}=4.1\$ is shorted to a p- layer with doping \$N_A=6.5 \times 10^{13} cm^{-3}\$. If the hole mobility is \$450 cm^{2}/(V.s)\$, and the emitter fingers \$0.34 cm\$...
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499 views

Does a semiconductor follow Ohm's law?

Ohm's law is valid for metals, but is it valid for semiconductors? Does it work there? I am not talking about a PN junction here. If I have a block of silicon and pass voltage across it, will I ...
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56 views

clamping the battery voltage with zener diode?

I want to do an experiment with a battery I have. I have 200AH 6v lead acid battery and I want to charge it with maximum current the battery can take in bulk stage, then in float or acp. stages, I ...
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Will a Schottky diode save my LEDs against reversed voltage?

Consider the following schematic: simulate this circuit – Schematic created using CircuitLab Main question: 1) I am accustomed to use Schottky diodes to protect my circuits against reverse ...
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159 views

Can tesla valve concept work for electrons?

This is a Tesla Valve. It works by diverting liquid or gas back on itself when it is flown in one direction and allowing a smooth flow in the other direction. Can the same concept be used to create a ...
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41 views

Zero Voltage in a power semiconductor chip

In an ON-mode silicon IGBT chip operating within a real power module, is the collector contact fixed at 0 V or emitter? What about Power SiC MOSFET? enter link description here
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177 views

How large is the percentage of non silicon materials in overall production capacity for semiconductors?

Most of all semiconductors produced these days are made from silicon, as it is easy and cheap to manufacture in very well researched bulk processes. But some electronic devices require the physical ...
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Question about transitor NPN [ALFA;Strange configuration;Exit characteristic]

first of all thanks for read and for your time, I have a few questions about transistor: 1) I can't understand why my book say: Ic=Icb0+alfa*Ie and not ...
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3answers
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Is there a way to experimentally separate the effects of gate voltage?

I'm currently doing experiments on new kind of semiconductors. These devices have a body (source, drain) and a top gate. These devices show a response to gate voltage. The conductance changes with ...
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1answer
55 views

Problems with doping semiconductor materials in 7nm technology

As you know, semiconductor technology is going to reach 7nm lithographic precision soon. Which means that the smallest segment length on a semiconductor die can be as short as 7nm. After making some ...
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3answers
287 views

Why are we going from DUV straight to EUV lithography?

The current lithography machines use 193 nm light, and for the past 10 years we've been waiting for extreme ultraviolet machines, that emit 13.5nm light. It's pretty obvious that the this challange ...
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37 views

Total Power Dissipation - Design Margin

It is good practice to ensure some design margin for the electronic circuit in terms of absolute maximum ratings. What is the proper way of selecting such a margin for Total Power Dissipation? Let's ...
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2answers
111 views

Forward voltage across the diode

If the diode's dynamic resistance was zero , will not we be able to increase the voltage across the diode above 0.7 v ? (I am assuming forward bias ) I am asking this question because my book ( ...
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1answer
45 views

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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Excess Carrier Generation and Recombination

Excess Carrier Generation and Recombination : The net rate of change in electron concentration is given by: \$ \frac{dn(t)}{dt}=\$ Thermal generaton rate-Recombination Rate \$ \frac{dn(t)}{dt}=\...
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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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Temperature-dependent leakage current in IGBTs

On one hand, the leakage current of power electronics modules such as IGBTs depends on the temperature. On the other hand, the temperature distribution on the IGBT chips is significantly non-uniform ...
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55 views

Design a DC motor with a transistor

I am trying to design a DC motor with transistor. Following image shows the exact way I am trying to do so. How would I go about doing so, I am not so familiar with transistors, but something that ...
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3answers
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BJT Active mode - How does it work

I am finding it difficult to understand how exactly this works and would appreciate any help. From my understanding: The emitter base junction has to be in forward bias meaning that Vb is more ...
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3answers
98 views

Understand of Unijunction Transistor

Unijunction transistor is a semiconductor device that can be represented as shown: It forms a voltage divider with a diode pointing towards middle of divider marked as \$\eta V_{BB}\$ (where \$\eta\$ ...
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2answers
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Designing a circuit that opens when less than 12 volts are applied and closes when more than 12 are applied

I'm looking to build a circuit where current only flows when there is a potential difference across the entire circuit of more than 12 volts (+- 0.1 V). I also need there to be only a small amount of ...
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1answer
61 views

Estimate temperature for silicon (p-n junction)

I need to estimate the temperature at which p-n junction made of silicon lose it rectifying characteristics. (\$N_A=N_D=10^{15}\,cm^{-3}\$) \$E_G\$ is independent of the temperature and are 1.12 eV ...
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2answers
104 views

Cause of triode mode in MOSFET

My reference text introduces the MOFSET as follows: The text says the induced channel has uniform width as long as \$v_{DS}\$ is small, because in that case \$v_{GD} = v_{GS} - v_{DS} \approx v_{GS}\$...
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0answers
35 views

What are all the different diode current regions in the forward bias operation?

I know there is the usual drift-diffusion current, the Sah-Noyce-Schockley current and the Mott-Gurney high injection region; all these region governed by their own separate regions. I was wondering ...
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3answers
126 views

Latch-Up in CMOS-Devices

I recently read something about the latch-up effect in CMOS-Structures but I don't understand why are MOSFETs affected by this effect. I understand that high currents through the source-drain path ...
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120 views

Majority Carrier Devices

Why majority carrier devices have higher ON state resistance compared to the ON state resistances of minority carrier devices?
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Why is Ic constant in the plot of Vce vs Ic in a common emitter NPN transistor (in active region)?

In this plot, when \$V_{ce}\$ increases in the active region, shouldn't \$I_c\$ also increase as more electrons are getting diffused into the collector? Then, why is it that for a large range of \$V_{...
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1answer
34 views

TVS diode with 10 - 15 V forward voltage

I came across this TVS diode: https://m.littelfuse.com/~/media/electronics/datasheets/tvs_diodes/littelfuse_tvs_diode_smf3_3_datasheet.pdf.pdf It has a forward voltage drop of 10 to 15 V. Why? How? ...
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1answer
181 views

MOSFET: How can I find conduction parameter and transconductance based on graphs?

So I have my graphs (below) with various MOSFET characteristics. I don't know device dimensions or geometry, therefore I can't solve for the 2 directly with an equation. Otherwise I would just do that....
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2answers
102 views

What happens to the semiconductor in an LED when it is given voltage that it cannot handle?

Let us suppose we have an LED with the allowed voltage range of 1.5V to 4.5V and we gave it somewhat 12V. Now we know that the LED will instantly stop forever. But I want to know what will happen to ...
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1answer
95 views

Are there semiconductor materials with hole mobility greater than electron mobility?

Every material I've ever seen has a hole mobility much less than its electron mobility. For silicon, it's by a factor of two or three; for gallium arsenide it's more like twenty. But are there any ...
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71 views

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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1answer
53 views

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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0answers
105 views

Photo-conductivity of n and p type semiconductors

Both n-type and p-type semiconductors are available to fabricate a photoconductive devices. To achieve the highest photoconductivity, do you want to use n-type or p-type? Why? $$σ_{ph}=q(μ_n ∆n+...
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44 views

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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0answers
60 views

How does a MOSFET conduct in saturation region?

It is a simple question but I could not find a straightforward answer. When a MOSFET enters saturation region, the channel length starts to decrease, and the channel width is the smallest near the ...
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2answers
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Is the resistance between collector and emitter is lower that of the path between collector and base? [closed]

If no, pls tell me why. And if yes, my question is how can the path C-B-E be have lower resistance than that of B-E? Shouldn't the resistances of BE and CB add up cause they're in series?
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240 views

Why can't a combination of two diodes connected back to back act like transistor? [duplicate]

I saw an explanation of the transistor working here by Bill Beaty. I absolutely loved it. But I'm not entirely sure why the action cannot be achieved by two diodes connected back to back by a metal ...
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1answer
128 views

The forward voltage Vf of a diode

I want to know about the forward voltage \$V_{f}\$ parameter of a diode device, given an I-V charateristic curve and in ambient temperature. What is the criteria to define the \$V_{f}\$ for any diode? ...
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1answer
48 views

How deep does the depletion region in power diode penetrate the lightly doped n- layer under no bias?

I could find references for describing the depletion layer in a power diode under reverse bias and the consequent classification of Non-punch through and Punch-through diodes. But I couldn't find a ...
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1answer
670 views

Why do power diodes have a p+ n- n+ construction and why not p+ p- n+?

I've been learning about power diodes and how they differ from low power diodes with the addition of a lightly doped n-type layer. This n-type layer improves the breakdown voltage rating of the ...
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1answer
47 views

Ic and Vce equations of IGBT

I know in IGBTs while operating, parameters Ic (collector current) and Vce (collector-emitter voltage) are Tj (junction temperature) and Vge (gate-emitter voltage) dependent. Is there anything else ...
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Calculation of Vce from Ic-Vge Characteristic

We have found the Ic-Vge (collector current vs gate-emitter voltage) characteristic of an IGBT device as shown below at a high Vce (collector-emitter voltage) value (here 20V) from the datasheet (...