Semiconductor Electronics Materials Devices and Simple Circuits - Result Question 22

22. A pn photodiode is fabricated from a semiconductor with a band gap of 2.5eV. It can detect a signal of wavelength

(a) 4000nm

(c) 4000\AA

(b) 6000nm

(d) 6000\AA

[2009]

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Answer:

Correct Answer: 22. (c)

Solution:

  1. (c) λmax=hcE

=6.6×1034×3×1082.5×1.6×10195000\AA

The wavelength detected by photodiode should be less than λmax. Hence it can detect a signal of wavelength 4000\AA.



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