All Questions
Tagged with semiconductors diodes
136
questions
7
votes
5
answers
3k
views
Series connection of diode and resistor. Why is there a constant voltage across the diode?
So I know that a diode can be described using the Shockley equation and after a certain voltage, the diode current begins to increase rapidly. The nominal 0.7 volts. I also know that this voltage ...
- 81
0
votes
1
answer
66
views
What is a precise definiton of "cut-in" voltage as applied to diodes?
What is the "cut-in" voltage or knee voltage of a diode or transistor?
In a lot of books I read that the cut-in or knee voltage of a diode (or transistor) is when the diode starts conducting ...
- 1
3
votes
2
answers
144
views
Interpreting Diode-Module Datasheet (Voltage Drop)
I'm trying to interpret the datasheet of a Dual-Diode Module, specifically the MF200C12F2N. The internal Circuit Structure is given below:
The Forward Voltage is given as 2.3V without any further ...
- 33
0
votes
1
answer
61
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Clarification on Diode Recovery Times and Conduction State
I have a diode in my circuit with reverse voltage of 100 V and forward voltage of 2 V.
It experiences a reverse voltage of 100 V and immediately the voltage changes to 10 V in forward direction so it ...
0
votes
2
answers
232
views
Using tunnel diode to cancel out armature resistance
Can we use tunnel diodes to cancel out armature resistance?
A tunnel diode when it is in its negative differential region under DC shifted AC(AC with some DC offset) and if the Vp-p of the AC is very ...
0
votes
3
answers
188
views
Semiconductor theory
Why is there no resistor in the circuit when analyzing hole and electron currents according to semiconductor theory?
- 31
1
vote
1
answer
569
views
Understanding the formula of the saturation current in a PN-junction diode
According to Wikipedia, the saturation current in a diode is given by the following formula:
$$I_S = qAn_i^2\left(\frac{1}{N_D}\sqrt{\frac{D_p}{\tau_p}} + \frac{1}{N_A}\sqrt{\frac{D_n}{\tau_n}}\right)$...
- 121
0
votes
1
answer
106
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Contribution of hole diffusion current and electron diffusion current in a pn junction
I have recently got to learn that the hole diffusion current and electron diffusion current both point towards the N side in a PN junction? And the diffusion current is hence towards the N side.
And ...
- 23
0
votes
1
answer
50
views
Drift Current in PN Junction and Barrier Voltage
I am reading this book, but the idea presented by it is very unclear.
It quotes:
However, I am not entirely convinced with the reason it provides here, like why are the minority carriers that reach ...
- 23
3
votes
1
answer
101
views
Why is diffusion current due to p side in a diode inversely proportional to doping concentration of p side in the case of forward bias?
In a diode at equilibrium, there are Pn holes on the n side of the junction. These are maintained by the dynamic equilibrium of diffusion due to holes = drift due to holes. When a forward bias is ...
0
votes
1
answer
145
views
Why doesn't a diode pass current when reverse biased?
If one tacks a P-type semiconductor to an N-type semiconductor, a P-N junction forms in which electrons diffuse from the N-type to the P-type causing a diffusion current. Some time passes, and an ...
- 361
0
votes
1
answer
403
views
Fermi levels in PN-junction under forward bias are not constant throughout each side
This is, in a way, a follow-up to this question.
I see the following band diagram for a forward biased diode everywhere:
In the above picture, I marked a point with potential zero (where battery is ...
- 163
16
votes
5
answers
4k
views
Resistance depending on voltage - the chicken and the egg?
If I understand correctly:
The resistance of some circuit components (like diodes) depends on the voltage across them.
When two components are connected in series: \$\frac{V1}{V2} = \frac{R1}{R2}\$
...
- 181
0
votes
1
answer
71
views
Diodes in parallel reduce current compared to single measurement
I have a photonics integrated circuit with two quantum well diodes. (exact description below)
If I measure the IV curve for each individual diode I get pretty much the same curve for both. but if I ...
0
votes
1
answer
54
views
What does the interface between lead(s) and the silicon chip look like inside a semiconductor package?
For a leaded semiconductor, like a diode or a transistor, one of the leads is usually the same piece of metal as the copper pad/heat spreader on the back, which is also shorted to one of the junctions ...
- 749
0
votes
1
answer
65
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 ...
- 91
2
votes
1
answer
786
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
121
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 ...
- 91
0
votes
0
answers
57
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 ...
- 749
7
votes
5
answers
2k
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 ...
- 189
0
votes
1
answer
256
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 ...
- 491
0
votes
1
answer
2k
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 ...
- 101
0
votes
1
answer
561
views
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 ...
- 37
1
vote
2
answers
228
views
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:
- 125
2
votes
1
answer
166
views
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 ...
1
vote
1
answer
144
views
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 ...
- 111
1
vote
1
answer
110
views
Majority Charge carriers and electron holes
Suppose I have an extrinsic semiconductor made of silicon and doped with phosphorous. Now, phosphorous has one more electron than silicon. After replacing one silicon atom, and taking its place, the ...
0
votes
2
answers
133
views
Find the output voltage of a diode circuit with two batteries connected in parallel
When Vi<-2V, the D1 & D2 both will be turned on and both of them will be considered as short circuits. But how do I find the output voltage with two batteries connected in parallel like this? I'...
- 3
0
votes
1
answer
737
views
Electric field of Schottky diode
Reference: Device Electronics for Integrated Circuits 3rd Ed. Richard Muller
I am trying to understand how to calculate the maximum electric field. The answer given in the book is $$E_{max} = \frac{-q ...
- 447
0
votes
1
answer
208
views
Voltage fluctuation due to AC in a half wave rectifier
I think I get the broader idea of using a diode as a half wave rectifier, but I have a question:
Who provides the forward voltage or knee voltage to start the diode for rectification? I am assuming it ...
- 271