A diode, which can turn current ON and OFF in nanosecond is called:
Correct answer: C. Photodiode
- A. Photo voltaic cell
- B. Light emitting diode
- C. Photodiode
- D. None of these
Explanation
There are two relevant mechanisms:First, the intended one: Minority carriers, generated by light within or close to the p-n junction and therefore depletion region, reach one of the contacts and therefore are lost for additional transport. This is the contribution, which you can measure externally as generated current or voltage.Second: Photo-generated carriers can also recombine due to scattering mechanisms and recombine with a carrier of opposite sign. Again, this particular carrier pair is lost for future transport. Scattering mechanisms could be crystal defects in the semiconductor material, impurities, phonon-assisted scattering due to elevated temperature, etc. Therefore, every material or heterostructure has some characteristic carrier life time, which determines the shut-off behavior in this case.
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About Electronics
A p-n junction forms when p-type and n-type semiconductor regions meet, creating a depletion layer, barrier potential and rectifying action. The work covers forward and reverse bias, junction current, diode characteristics, and how a diode converts alternating current into pulsating direct current through half-wave and full-wave rectification.
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