Semiconductor Electronics Materials Devices and Simple Circuits - Result Question 24
24. A p-n photodiode is made of a material with a band gap of $2.0 eV$. The minimum frequency of the radiation that can be absorbed by the material is nearly
(a) $10 \times 10^{14} Hz$
(b) $5 \times 10^{14} Hz$
(c) $1 \times 10^{14} Hz$
(d) $20 \times 10^{14} Hz$
[2008]
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Answer:
Correct Answer: 24. (b)
Solution:
(b) $E_g=2.0 eV=2 \times 1.6 \times 10^{-19} J$
$E_g=h v$
$\therefore v=\frac{E_g}{h}=\frac{2 \times 1.6 \times 10^{-19} J}{6.62 \times 10^{-34} Js}$
$=0.4833 \times 10^{15} s^{-1}=4.833 \times 10^{14} Hz \simeq 5 \times 10^{14} Hz$
