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.

Filter by
Sorted by
Tagged with
3 votes
2 answers
244 views

How do the BJT collector and emitter portion compare in terms of size and charge density?

The diagram of a BJT implies that the two p-n junctions are identical. However, I do know that they are not since we cannot connect the transistor the other way around i.e swap emitter and collector, ...
  • 1,497
1 vote
1 answer
47 views

Clarification of 'case' in junction to case thermal resistance

Junction to case thermal resistance (Rjc) is a key parameter when characterizing a package. It can be expressed as the temperature difference between the two locations over the heat dissipation. I am ...
  • 689
1 vote
3 answers
60 views

How does one manufacture a P-N junction?

When I read a physics textbook about a P-N junction, it will tell me that you connect a p-doped semiconductor to an n-doped semiconductor, and you form a depletion region. However, from what I know ...
  • 111
1 vote
1 answer
81 views

What does this schematic symbol mean (transistor with two emitters)?

Basically the question is, what it is? Are those two emitters (meaning that part of semiconductor heavily doped)?
  • 309
11 votes
3 answers
1k views

What does the 'junction' of a silicon semiconductor look like in real-life?

The P-N junction is a small area within a package where heating is most prominent. Junction temperature is a key parameter we try to track when operating a diode or a transistor. I am wondering what ...
  • 689
0 votes
1 answer
39 views

Why do we use LDD technique in IC fabrication technology?

Why do we use LDD(lightly doped drain) in IC fabrication technology? In the "silicon VLSI technology" book, was mentioned that this is in order to create a voltage drop in drain region. So ...
0 votes
0 answers
80 views

Why is the MOSFET not behaving as per standard device characteristic curve?

A MOSFET has 3 modes of operation: 1.Vgs < Vth => Cutoff 2. Vgs > Vth and Vds < Vgs − Vth => linear region The MOSFET operates like a resistor, controlled by the gate voltage relative ...
  • 2,187
1 vote
0 answers
83 views

Need help identifying this PCB component

I have a device with a small chip that needs to be replaced. On one of my devices the chip reads "L1t" on it, and on another one of the same kind of device it reads "L1-". They ...
0 votes
0 answers
58 views

Bandwidth: voltage-source vs. current-source gate drivers

Why do voltage-source gate drivers provide low-to-medium bandwidth that does not work well for wide band gap devices, while current-source gate drivers provide hundreds of MHz of bandwidth?
  • 139
1 vote
2 answers
61 views

What is the reason why thermal aging affects only the Cds capacitance but not the Cgs or Cgd capacitances?

Please take a look at the following images, experimentally obtained from a power cycling test of a power MOSFET. After the test where thermal aging is created due to repetitive power cycles, it is ...
  • 139
1 vote
1 answer
93 views

Is there anywhere I can download BJT Transistor I-V data?

Is there anywhere I can download some current-voltage data for a bipolar junction transistor? (It doesn't matter that much which one.) To explain further, for a simple BJT circuit we have the ...
1 vote
0 answers
17 views

How to calculate accumulation charge concentration (/cm3) as a function of dist. from the oxide-semiconductor interface in a MOS cap with n-type semi?

I am trying to calculate the accumulation charge concentration (/cm3) for the MOS capacitor with Au/TiO2/n-InSb, where n doped InSb is the substrate. So far the material I found focuses on p-type ...
0 votes
3 answers
126 views

Can we make a battery with a semiconductor?

Can we make battery with separate P and N junctions?
0 votes
1 answer
40 views

Why in the output characteristic graph of BJTs, within the saturation region, is the collector current positive?

It is known that in the saturation region of the BJTs the pn junction is reverse biased. The reason for being reversed biased could be explained as follow: Vce=Vcb+Vbe Therefore Vcb=Vce-Vbe We can see ...
  • 81
2 votes
1 answer
285 views

What are wettable flanks in semiconductor packages?

What are wettable flanks? Is there any difference between packages with wettable flanks and other leadless packages? Can we say the package given above has wettable flanks?
2 votes
1 answer
39 views

Why aren't the majority charge carriers attracted by terminals of a battery when the p n junction is reverse biased?

It is clear that when the junction is reverse biased, the free electrons from the n side can not pass the depletion layer and fill the holes in the p side. But why will the free electrons not move ...
  • 81
5 votes
1 answer
289 views

Semiconductors: electrons more mobile than holes despite being heavier?

I apologize if this is a very basic question. But I have always known it to be true that in Silicon, electrons have higher mobility than holes. From my semiconductor physics classes in first year, the ...
0 votes
0 answers
35 views

Power dissipation vs. heat dissipation for transistors and diodes

Are these two concept the same or different for semiconductors? Some power MOSFETS have power ratings in the hundreds of watts, and that's way too high for heat loss. I try to understand 'power ...
  • 689
3 votes
3 answers
230 views

Does body diode reduce MOSFET switching loss in a power converter?

In power converters, it is common that MOSFETs are fed a PWM signal to have cyclic switching. Part of the power is lost in the process. Does the body diode reduce this loss? It seems most power ...
  • 689
7 votes
1 answer
777 views

Why is a Zener diode's temperature coefficient ±0mV/K at approximately 6V?

I am familiar with Zener diodes and their parameters. It's interesting to see the same temperature coefficient at approximately 6V across different manufacturers and different packages. See below ...
0 votes
1 answer
143 views

MT3608 wrong output voltage

I designed a 24V boost converter circuit using a input voltage of 5V shown below: After producing the PCB for this, I tested the output voltage and found that the output voltage was at 5V instead of ...
  • 121
1 vote
2 answers
110 views

Is there a microscopic oscilloscope probe?

Does such a device exists to measure voltage and current in 14nm and below semiconductors?
  • 157
0 votes
0 answers
52 views

What is Electromagnetic Cross Section?

What is Electromagnetic Cross Section? (shock section) Hello, I have a question regarding the manufacturing process of electronic components in the case of the silicon deposition and corrosion process....
  • 363
7 votes
5 answers
1k views

Why can't a P-N junction diode be used as a voltage regulator or reference in forward bias?

Usually, a Zener or avalanche breakdown region for a suitably doped P-N junction is used for voltage regulation as a substantial variation in the current (due to minority carriers) requires a ...
1 vote
0 answers
50 views

Why do we dope low amount of impurity atoms in a semiconductor?

I read that the doping ratio is usually around 1 impurity/10 million atoms. Why is that ratio so low? Can’t the semiconductor conduct electricity better if there were more charge carriers?
1 vote
0 answers
25 views

PN circuit, playing with doped wafers

So I have two silicon wafers. One is P type (doped with boron) and one is N type (doped with phosphorus). I am just playing around with these and thought to myself, "can I make a diode if I ...
0 votes
2 answers
95 views

What is the law regarding certification of paper electronics for EU and US

The question is explicitly aimed at paper electronics. No classic/typical PCB (fiber glass or typical material PCB's are made of) is attached to the paper. The circuit layout is directly printed/...
0 votes
1 answer
38 views

Do conduction electrons recombine with positive donor atoms?

Once the 5th valence electron of a donor atom left, it will be to the conduction band, so the donor atom becomes positively charged. My question is if it is possible, that a free electron from the ...
2 votes
1 answer
49 views

Hole current in p-type semiconductors

I know about p-type semiconductors and that there are holes as majority carriers present in the semiconduction. If we apply current through this semiconductor electrons from the valence band will come,...
1 vote
2 answers
75 views

Do holes in a semiconductor just move when there is a current going through the semiconductor?

If a current travels through a semiconductor holes travel to the "end" of a semiconductor, where they can recombine with incoming electrons. Does this also occur if there is no current ...
4 votes
2 answers
128 views

Why does touching LEDs' ground terminal light them dimly?

Today I was making a little circuit with an LED strip (3 LEDs in series) and I noticed a curious fact that I am not sure how to explain. I wasn't sure of the operating voltage of the LED strip, so I ...
0 votes
1 answer
54 views

Why is intrinsic carrier density only equal to hole - or electron concentration?

If carriers can be holes or free electrons, why isn´t the intrinsic carrier concentration equal to the sum of the free electron concentration and the hole concentration in the semiconductor?
0 votes
0 answers
34 views

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 ...
1 vote
1 answer
47 views

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 ...
0 votes
1 answer
105 views

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 ...
0 votes
1 answer
87 views

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 ...
  • 11
4 votes
4 answers
603 views

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 ...
  • 174
4 votes
2 answers
792 views

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 ...
  • 67
5 votes
3 answers
320 views

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 ...
1 vote
1 answer
127 views

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 ...
0 votes
0 answers
103 views

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 ...
0 votes
1 answer
115 views

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 ...
5 votes
3 answers
573 views

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 ...
  • 979
0 votes
2 answers
95 views

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 "...
1 vote
0 answers
49 views

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 ...
2 votes
0 answers
77 views

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, ...
  • 863
2 votes
0 answers
63 views

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 ...
  • 165
0 votes
1 answer
259 views

Current density in an ideal PN junction diode

I found that the current density is as above. The first question is: the logic is that when there is no external voltage applied, the diffusion current cancels the drift current. But there are four ...
6 votes
3 answers
555 views

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.
  • 2,187
1 vote
0 answers
97 views

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?

1
2 3 4 5
14