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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Mathematical proof of mass action law

To mathematically prove the mass action law I often see that people set the rate of recombination equal to the rate of generation. Now I don´t understand why this is the case in an N-type ...
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Is generation and recombination same in extrinsic semiconductors?

For example, if we have an n - type semiconductor, so there are more electrons in the conduction band. So wouldn´t the recombination rate increase, opposed to the generation rate, because there are ...
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Reset on lockup, by discrete analog components [closed]

Way back when in the 80s/90s in a C64 magazine was an electronics project described. By adding a piece of code, the C64 would send a signal (pulse of power) to the electronics. If that stopped, the ...
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Challenges in implementing super large architectures in latest ASIC (9nm or 12nm or similar)

Recently I came across a few papers that simulate super large accelerator architectures in the latest ASIC, e.g., 9nm or 12nm standard cell libraries. Typically these papers report synthesis results ...
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Feasibility of building a benchtop chip fab for prototyping

This is generally quite a vague question as I'm new to the space but I've been thinking a lot about prototyping in the IC/semiconductor space and have been wondering about the feasibility of ...
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Relation between collector current and Vce voltage in saturation mode

I have confusion regarding how collector current affects the voltage across collector to emitter in NPN transistor (2N4123). How do I interpret this graph? Can I say when collector current increases ...
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Can I make a homemade Peltier module with constantan wire?

I'm trying to make my own Peltier module. I ordered constantan wire, which I used as N-type semiconductor and iron wire as P-type. I made this and powered it with 3V, but without response. What am I ...
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Potential distribution in MOSFET

Let us assume that an NMOSFET has its source, drain and substrate grounded therefore VDS and VSB=0 V . We apply a gate voltage VGS=2 V and I want to know how this potential is distributed as we move ...
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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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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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Select zener for minimal thermal drift

The voltage of a Zener diode in the Zener breakdown region depends on temperature. Suppose we have 3 Zeners with the following specs: 3.3 V rated Zener voltage at 5 mA 5.1 V rated Zener voltage at 5 ...
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BJT: definition of "edge of saturation"

The book Sedra/Smith (Microelectronic circuits) tells in chapter 5 the following: My question: I found no statement on why the EOS is defined by the point where vc < (vb - 0.4V). Seems like other ...
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Could we use holes in an NMOS?

In an NMOS we have a p-substrate, and we use a positive voltage to attract negative charge "to the top". But could we have used negative charge to attract holes instead and gotten a "...
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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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Why BJT thermal voltage can be not equal to kT/q in SPICE3

In SPICE, apart from effects such as basewidth modulation and base-collector leakage the collector current is given by the expression (according to the original SPICE2 PhD work) But actually, ...
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What would a theoretical Group II, Group IV Transistor's Properties be? [closed]

This question is for more than a theory. I would like to disprove that what I'm working on is not a Group II, Group IV transistor. I know they CAN exist. I don't know why they don't exist or what ...
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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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Why is the Base-emitter ON voltage as high as 2V in the BJT datasheet?

Below is a snippet from a BJT datasheet. Why is the Base-emitter ON volatge mentioned as 2V? The Base emitter voltage should be 0.7V when the BJT conducts.
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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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Is an NMOS device symmetrical with regard to its D and S pins? [duplicate]

Can D and S be swapped? (Assuming the body is not internally connected to S.) The structure of a MOSFET is totally symmetric. Even the LTspice simulation shows that it can be swapped. Does this ...
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Purpose of field implant in semiconductor manufacturing

I recently joined the semiconductor manufacturing industry. In one of the process flows, I see a stage that has extra boron implantation step (called the field implant) in the P-WELL region. I've ...
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7 votes
1 answer
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Why is the collector very lightly doped in a bipolar junction transistor?

Many websites and courses list the doping profile of a BJT as "emitter heavily doped", "base lightly doped" and "collector moderately doped". However, the more reputable ...
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What is the correct carrier concentration equation to use?

In this book I am reading, it gives the intrinsic carrier concentration as: \$ n_i = \sqrt{N_c\cdot N_v} \cdot e^{({\frac{-E_g}{2*K*T}})} \$ While another book says the carrier concentration is: \$ \...
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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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Shelf life of semiconductor part number CY8C4245LQI-483 Infineon Technologies [closed]

What is the shelf life of semiconductor part number CY8C4245LQI-483 made by Infineon Technologies? Can we use these parts after 5 years of manufacturing?
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Why does the Schottky barrier height remain constant?

If a metal and a semiconductor are connected, they are going to equilibrium. For this, the Fermi level has to be equal. So far I understood that this causes a charge exchange till said equilibrium has ...
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Finding peak common-emitter gain from graph

It is known that common-emitter current gain: $$B_f=\frac{I_C}{I_B}$$ but, how do I find its peak? Ans how can I estimate common-emitter current gain? I have the widths and diffuison constant. Do I ...
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How do processor transistor counts keep increasing, without geometric scaling?

Reading into the history of the semiconductor industry and Moore's Law, and looking at the ITRS/IRDS documents, I understand that scaling down and modern node names (7nm, 5nm etc) are now "...
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How \$V_{th}\$ is calculated in MOS structures?

I'm an electronic engineering student, I've already studied the theory, but it seems that I'm missing something randomically from most of the chapters, so today I'm showing you a question of an exam's ...
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1 answer
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Semiconductor chip shortage [closed]

Does anyone have an answer why do chip distributors have almost virtually zero stocks? Is there a shortage?
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High Voltage PMOS devices availability

Generic question for experts well versed in semiconductor device physics. Most of the high voltage power switching devices seen are N-Channel (Silicon and Silicon Carbide) with varying ratings. Is ...
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Troubleshooting Skyper 32Pro R + Adapter Board 1 Skyper 32Pro R

Hello I am trying to test an IGBT SKM145GB066D with the Adapter Board 1 Skyper 32Pro R and gate driver Skyper 32 Pro R, but cannot make it work. I've spend 2 weeks trying, but it seems like some ...
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Calculate V for given circuit [closed]

Consider the diode circuits in Figure. V1 = 5 V, V2 = 0, and VCC = 6 V. Assuming ideal diode model, determine V0. I assumed both d1 and d2 to be ON but how to calculate further? I have no idea please ...
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Magnitude of current

The current of a germanium diode at room temperature is 100 uA at a voltage of -1 V. Predict the magnitude of the current for voltages of 0.2 V and -0.2 V at room temperature. Repeat the prediction ...
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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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What is the physical model for energy flow in or around a lossless conductor during transient analysis? (Veritasium Electricity in Wires)

Context Veritasium - The Big Misconception About Electricity - Energy Doesn't Flow in Wires Note I do not agree with the answer (D) given by Veritasium which is only plausible if any tiny current ...
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Why can't electrons leave the N side and enter the P side in reverse bias?

Why can't electrons (excess electrons) of the N side of a semiconductor diode enter the P side via the battery in reverse bias mode of PN junction? like this:
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2 votes
1 answer
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Diodes made using separate p and n-type semiconductors

Can a diode be made by connecting, in series, separate n and p-type semiconductors? Assume that all ends are attached to Ohmic contacts. I am hoping that this will prevent any discontinuities in the ...
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2 votes
2 answers
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Why aren't aluminum and nitrogen used as dopants in semiconductors, chips, etc.?

Boron is most commonly used for the p-type dopant, and phosphorus for the n-type, correct? Why not aluminum for the p-type and nitrogen for the n-type? Is it just a matter of cost and/or convenience?
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Energy band diagram of a polar material

For a single piece of a polar material (ex. GaN, AlN, etc), there exists a constant electric field inside the material due to the bound charges at the surface. Above figure shows the resulting band ...
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1 vote
2 answers
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MOS capacitor - why is the total capacitance just the oxide capacitance C_ox?

All of the textbook that I have read mention that the total capacitance is just the oxide capacitance (Cox) for a MOS capacitor in an inversion and accumulation mode. It makes sense that is true for ...
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What does "field" in field oxide mean?

This is an excerpt from Design of Analog CMOS Integrated Circuits by Behzad Razavi. What does "field" in field oxide mean here, electric field?
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The accumulation region of metal ptype in a negative voltage applied to the gate

For a metal-p-type semiconductor boundary, I know how to compute the depletion width when no voltage is the applied to the metal, as below: How to compute the accumulation width of a metal-p-type ...
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12 votes
5 answers
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Why is silicon necessary in making semiconductors?

Can you make a diode just by connecting a piece of N-type material like phosphorus to a P-type material like gallium? Why are they added to silicon?
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Why N type MOSFET is used for low side and P-type for high side switching?

Typically N-MOSFET is used for low side switching and P-Type for high side switching. That's why transmission gates use both N and P-type MOSFET. But I can't correctly understand how a P-Type for the ...
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Why does the majority carrier concentration near the junction not decrease under forward bias? (PN junction)

We see that the current due to the majority carrier decreases near the junction as shown above, which means the majority carrier concentration should also decrease since the diffusion current is given ...
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PN junction depletion capacitance

I am having difficulty understanding the PN junction capacitance. I can't seem to figure out what exactly forms the two plates of the PN junction capacitance and what is the positive and negative ...
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4 votes
2 answers
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What does the cross point of V-I curves mean?

Here you see a V-I graph including many curves achieved under different junction temperatures of an IGBT. As it can be seen there is a cross point where all curves intersect each other. Does it make ...
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Ambiguity of the "intrinsic" layer in a PIN diode

I'm having trouble understanding the fundamental makeup of large PIN diodes, specifically those used in radiation detection devices. For example, high purity germanium (HPGe) detectors are often ...
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1 vote
1 answer
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Thyristor latching current and holding resistance

Is there a formula for calculating the latching current of a thyristor and the resistance of the thyristor after it forward conducts and I_gate becomes 0? I couldn't find anything online; the ...
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