Questions tagged [pn-junction]
For questions about p-n junctions, which are the boundaries between p-type and n-type semiconductors and are building blocks for diodes, transistors, etc. Only use for questions about p-n junctions themselves -- do not use for questions about circuit elements that happen to contain p-n junction(s) unless the question is specifically about the element's p-n junction(s).
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Why don't LED datasheets specify a maximum rated voltage?
I understand that (i) LED's have forward voltage drops (Vf) and (ii) that exceeding the dissipation wattage or max current can damage the device; thus one uses a series resistor to limit the current.
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How fast and far do electrons move in a diode during reverse bias?
When I have looked at videos on how diodes work, they make it seem like the electrons move extraordinarily quickly during reverse bias and quite a bit to expand the depletion regions. However, I would ...
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Why does photodiode junction capacitance affect operating bandwidth? (from a semiconductor physics model perspective)
Here is a typical equivalent circuit diagram of a photodiode.
I feel like this circuit model broadly makes sense to me. You have a diode, in parallel with the junction capacitance. The photocurrent ...
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Junction diode "built-in" voltages
When a PN Junction terminal are left open-circuited, the voltage measured between then is zero. The Junction voltage Vo does not appears. Because similar built in voltages arise at metal semiconductor ...
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How to best relate a case temperature measurement with the actual junction temperature?
If I have 4W of power dissipated through a transistor (as derived from measured current and the datasheet's on-resistance) and I measure 40 deg. C on the case of the transistor, what is the best way ...
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Reverse current in diodes
I'm getting started with electronics and couldn't help but wonder about this:
When the PN junction diode is reverse biased (P connected to the negative terminal and N connected to the positive ...
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Non-Schottky SiC diodes
Hopefully this isn't too much of a shopping question. I am looking for off-the-shelf silicon carbide P-N junction diodes, but all I can find are Schottky ones. Do P-N version ones even exist ...
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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 ...
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Understanding thermal instability breakdown in pn junctions
I am currently reading Sze (Physics of Semiconductor Devices, 3e, Chapter 2.4.1) and am trying to understand his discussion of thermal instability breakdown/runaway in pn junctions. I have also ...
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Confusion about why pn junction discussion insensitive to doping variations faster than Debye length
Sze (Physics of Semiconductor Devices, 3e) gives the following discussion which relates to how equilibrium electric fields/equilibrium potential build-up at thermal equilibrium are related to doping ...
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Semiconductor PN Polarity
When you apply voltage to the PN semiconductor and you achieve equilibrium, why is the N side still negative (-) and P side still positive (+) when considering that all of the ions have 4 valence ...
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Minority carriers in P-N junction
Are the minority carriers (free electrons in p-type and holes in n-type) created after the doping of silicon or after the n or p side get voltage across from a power supply?
And my second question is ...
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What is the Fermi level away from the p-n junction?
I understand that the Fermi level at the p-n junction must be the same between the materials forming the junction. To achieve this, the band energies of the n- and p-type materials are bent.
However, ...
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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)$...
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Why does the width of the depletion region decrease with the increase in doping concentration?
Should the depletion region be increasing in width as more and more ions are uncovered at the junction due to the diffusion of majority carriers from one side of the junction to the other? Then why ...
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