A p-n photodiode is fabricated from a semiconductor with band gap of 2.8 eV. Can it detect a wavelength of 6000 nm?

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asked Jan 11, 2018 in Physics by sforrest072 (157,439 points) 61 410 947

A p-n photodiode is fabricated from a semiconductor with band gap of 2.8 eV. Can it detect a wavelength of 6000 nm?

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answered Jan 11, 2018 by mdsamim (213,225 points) 5 10 15
selected Jan 11, 2018 by sforrest072
 
Best answer

Energy band gap of the given photodiode, Eg = 2.8 eV
Wavelength, λ = 6000 nm = 6000 × 10−9 m
The energy of a signal is given by the relation:

Where, h = Planck’s
constant = 6.626 × 10−34 Js
c = Speed of light
= 3 × 108 m/s

The energy of a signal of wavelength 6000 nm is 0.207 eV, which is less than 2.8 eV − the energy band gap of a photodiode. Hence, the photodiode cannot detect the signal.

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