Semiconductor Electronics Materials Devices And Simple Circuits Ques 28
28. A $p-n$ photodiode is fabricated from a semiconductor with a band gap of $2.5 $ $eV$. It can detect a signal of wavelength
[2009]
(a) $4000 $ $nm$
(b) $6000$ $ nm$
(c) $4000 $ $\AA$
(d) $6000 $ $\AA$
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Answer:
Correct Answer: 28.(c)
Solution:
- (c) $\lambda _{\max }=\frac{hc}{E}$
$=\frac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{2.5 \times 1.6 \times 10^{-19}} \simeq 5000 $ $\AA$
The wavelength detected by photodiode should be less than $\lambda _{\max }$. Hence it can detect a signal of wavelength $4000 $ $\AA$.
BETA
