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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17 views

Why this switch's current sense ratio sometimes increases and sometimes decreases?

The Infineon BTS50055-1TMA is a "smart" power switch that is basically a FET with current monitoring. The equation for calculating current is given by the first entry in the truth table on datasheet ...
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78 views

Intuitive way to think of transistor saturation current?

I am having a hard time understanding what saturation current (denoted Is in my textbook) actually means for a transistor. For a diode, it makes perfect sense, it's the approximate maximum reverse ...
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75 views

If a silicon cyrstal is connected to a battery does current flow through the wire?

In a circuit consisting of a pure silicon crystal with each end attached to a different terminal of a battery via conducting wire, is there a current flowing through the wire? It seems that there is ...
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79 views

Why do NPN/PNP transistors need to use doped semiconductors for the 'N' region?

By my understanding, as long as the P layers are properly doped (to have fewer free electrons), the electrons could not flow between collector and emitter until the P is given a satisfactory level of ...
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the transconductance of cascade MOSFET IF channel length modulation is NOT ZERO

What would the derivation of the cascode MOSFET transconductance in small signal analysis IF THE CHANNEL LENGTH MODULATION IS NOT ZERO, as most examples for the cascode mosfet transconductance say in ...
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Connecting phototriac substrate to adjacent pins

For a regulatory exercise I am analyzing the result of a short fault between a phototriac's substrate (MOC3023) and its anodes (one at a time). The datasheet warns ...
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1answer
84 views

Difference between the words 'die' and 'chip' [closed]

In some articles speaking about the IGBT power modules, we can see that the word 'die' has been used for calling the semiconductor component of IGBT device. However, other articles calls it 'chip'. ...
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14 views

Carrier concentration of pn junction in reverse bias

I'm trying to understand the effect of forward and reverse bias in the carrier concentration of a pn junction. I know that in equilibrium the first picture below holds. When we apply forward bias, the ...
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28 views

Energy level of the created holes when electrons from the Silicon atoms occupy the holes due to acceptor atoms

I read in an article that the addition of acceptor impurities contributes hole levels low in the semiconductor bandgaps so that electrons can be easily excited from the valence band into these levels ...
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30 views

Finding the resistivity of doped silicon sample

Given that the mobility of electrons and holes in silicon is given by equations 1 and 2, I'm trying to find the resistivity of a sample which has been doped with a donor density of: $$N_d=2\times 10^...
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68 views

Is there any research for chemical/structural method to prevent observing beneath chip packaging? [closed]

I want to prevent others from reverse-engineering the on-die ROM, using X-ray, microscope, etc.. I think it's best to inject some substance between chip and packag and when the chip package is ...
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55 views

Series Limiting Resistor?

I have used a 3.3v and a 4.7v zener diode and please what will be the amount of resistance to operate them without any issues. The test current for 3.3v is 76mA and for 4.7v is 53mA.
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35 views

MIS capacitors discharge

Do MIS Capacitors discharge completely or only partially due to lack of free charges? Inside the semiconductor there is a depletion region with no mobile charge carriers so they wouldnt move to the ...
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78 views

Semiconductor common emitter configuration

Please could anybody explain the CE configuration, the graphs of \$I_b\$ vs. \$V_{be}\$ and \$I_c\$ vs. \$V_{ce}\$. I can't understand which current remains fixed and how can one regulate \$V_{ce}\$ ...
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What is the minimum die area of a chip?

Silicon chips are made by slicing up wafers; in general, the fewer transistors a design needs, the smaller the area it needs, so the more chips you get out of a wafer, and the lower the cost per chip. ...
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52 views

What makes a semiconductor?

Wikipedia says the following: Conventional semiconductors like silicon have a bandgap in the range of 1 - 1.5 electronvolt (eV), whereas wide-bandgap materials have bandgaps in the range of 2 - 4 ...
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24 views

Short N region diode

A diode was manufactured by making an abrupt junction between a region of length \$W_p\$ having a concentration \$Na = 10 ^ {18} cm^{-3}\$ and a region \$ W_n\$ with \$Nd = 5.10 ^ {15} cm^{-3}\$ of ...
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61 views

What is meant by power well in IC terminology?

Intel PCH Datasheet refers to power wells: Core well, Suspend well, Active Sleep well. Is power well same as power rail/power plane? Does it have any connection with p-well or n-well in IC ...
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161 views

Why are orange diode lasers still not common although orange LEDs have been around for decades?

Nowadays you can find lots of cheap laser diodes emitting light at wavelengths such as 405, 450, ~640, ≥780 and, since recently, also ~520 nm. But it's really hard to find a laser diode emitting at ...
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Why does the forward voltage drop in a diode vary slightly when there is a change in the diode current?

I was going through Basic Electronics and Circuits by David. A.Bell and there it mentioned that the forward voltage drop in a diode varies slightly with a change in forward current - but there is no ...
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1answer
70 views

Cover element on LED component

From time to time I come across a solution in which uses an LED as in below picture: This particular component is placed inside the module located in car interior. Button backlight application. The ...
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1answer
37 views

Solar Module Voltage when bypass diode activate?

What happen to the voltage level when a solar module is shaded and one of its bypass diode is activated? Assuming this solar module has 3 bypass diodes. I have been reading and can't seem to ...
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48 views

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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36 views

Junction Temperature Estimation Error

When predicting the junction temperature (Tj) of semiconductor chips (for example IGBTs) by available thermal models such as FEM simulations, how much is the maximum permissible Tj estimation error ...
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1answer
1k views

How does it work when multiple companies sell the same IC? [closed]

Very common ICs are sold by many manufacturers, for example let's say the TL07x range (which is vintage, but does demonstrate the case). Inspecting datasheets of two manufacturers, TI and Diodes Inc,...
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38 views

Diffusion current causes drift current?

I was studying about currents in an injected semiconductor (by illumination) from Integrated Electronics by Millman and Halkias. They consider the diffusion hole current in an injected n-type open-...
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24 views

Gate Current Calculation and Practical Mosfet Selection

Vnoo3 is the drive voltage, and Ig is the gate current. What I am wondering is: 1) How to calculate the peak Ig on the rising edge of the pulsed gate voltage? For instance, using the spice image ...
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58 views

In the pao sah model of MOSFET!

Hi I'm studying semiconductor and i got stuck in the concept of MOSFET. In the case of pao-sah's model, we set our electron concentration and hole concentration as following pictures that I attached. ...
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22 views

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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1answer
24 views

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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38 views

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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1answer
41 views

Convert select / trigger coils to direct fire

Working on ignition system controlled by prehistoric ECU, it has 2 signals: select and trigger. Select switches CoilA and CoilB. Trigger controls dwell time. I want to purge old broken coils and ...
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67 views

Contact potential between metals

Metals Al and Au are connected in series. An ideal voltmeter, with both of its leads made of Cu, is connected across them. Then how come the voltmeter gives zero reading but why can't we measure ...
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82 views

What is the meaning of 1N, 2N, 4N, 6N (and probably others) in the semiconductors name? [duplicate]

There are many discrete semiconductors with names like 1N4148, 1N4007, 4N35 or 6N137... And they can be produced by many manufacturers. So it looks like it is not a marketing names. Looks like 1N are ...
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77 views

What is the term used for how many microns or nm for lithography used on silicon wafer?

I think as of 2019 it is said that 7 nm is the smallest possible? I wonder how much it was in 2010, 2000, and 1995 (it was micron instead of nm earlier). I hope to find the historical chart / data but ...
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3answers
100 views

What happens to a computer as it is cooled towards absolute zero?

What happens to the behavior of a conventional circuit using conventional components as it is cooled towards absolute zero? To make this question more relatable: What would happen as we cool a modern ...
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3answers
9k views

Why would a Intel 8080 chip be destroyed if +12 V is connected before -5 V?

The Intel 8080 is a classic microprocessor released in 1974, fabricated using an enhancement-mode NMOS process, and shows various unique characteristics related to this process, such as the ...
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2answers
86 views

Is it misleading to say “holes in semiconductors jump to the other side”? [duplicate]

I'm getting a little confused with the convention of saying that "holes in a semiconductor will move from p-side to n-side and electrons will move the opposite way". I have no trouble with the concept ...
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2answers
101 views

Where should I put a 3.3V Voltage Regulator?

I've stumbled across lots of schematics and one thing that I find is almost never consistent is where a certain regulator should go. I'm going to be using the LM1117 series. Should the 3.3V regulator ...
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4answers
258 views

Why reverse connected MOSFET start to turn on at Vgs<Vth?

The circuit shown below is implemented using two AO3400 N-MOSFETs. AO4300 datasheet here. The right-hand MOSFET is connected with normal polarity (Vds is positive), while the left-hand MOSFET is ...
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1answer
71 views

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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1answer
55 views

𝐶 C -𝑉 V characteristics of MOS capacitors for different material

For C-V curve below for 3 different materials, (Si, InAs, InSb). What material will be corresponding to curve A/B/C? My understanding is that C is inversely proportional to the dielectric constant in ...
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89 views

Ordinary LED response to nanosecond pulses

Can anybody explain to me the output waveform generated on pins of an ordinary LED when it is exposed to very short light pulses? I can clearly see that there is a precise difference in the length of ...
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2answers
129 views

Mosfet Threshold Voltage

from MOS theory we know that, in case of a P substrate, a Gate-Bulk voltage higher than a certain threshold value creates an inversion layer, in this case made of negative charges. This is also ...
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452 views

What is the significance of numbers (2,3) mentioned in SOT23?

Small outline transistor (SOT) packages have certain numbers which tell the package size, for example, SOT23 or SOT323. But what is the meaning of suffix 23 or 323?
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41 views

Find electron-hole recombination rate?

In an n-type semiconductor, the thermal equilibrium electron concentration (n0=1015/cm3) and the intrinsic carrier concentration (ni=1010/cm3). The mean life time of minority carriers is 1us. The ...
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1answer
76 views

Is Mica non-conductive?

Are mica flakes like ones found in makeup and body lotions completely non conductive and should I be worried if it gets inside the components of my computer? Or should I be more concerned about ...
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160 views

Difference between cutoff and subthreshold region of nmosfet?

I understand that some current does flow from drain to source when Vgs is below vth and Vds is greater than zero. But why this has a different name?(and a different region in Cadence virtuoso tool) ...
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23 views

Where do the electrons come from in nmos channel formation? [duplicate]

For a NMOS, when gate potential is increased from 0 to say 0.1V, the holes in substrate feel repulsion and moves away leaving negative ions behind. But what exactly happens when the gate potential ...
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1answer
156 views

Multi channel Mosfet driver ghosting between channels (with suggested fix)

I´m pretty new to the forum (as you will see by my limited electronics knowledge) and I have a wierd problem when trying to control some automotive fans at variable speed. The fans each have an ...

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