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Question: Answered & Verified by Expert
A p-n photodiode is made of a material with a band gap of $2.0 \mathrm{eV}$. The minimum frequency of the radiation that can be absorbed by the material is nearly
PhysicsSemiconductorsNEETNEET 2008 (Screening)
Options:
  • A $10 \times 10^{14} \mathrm{~Hz}$
  • B $5 \times 10^{14} \mathrm{~Hz}$
  • C $1 \times 10^{14} \mathrm{~Hz}$
  • D $20 \times 10^{14} \mathrm{~Hz}$
Solution:
1787 Upvotes Verified Answer
The correct answer is: $5 \times 10^{14} \mathrm{~Hz}$
$p-n$ photodiode is a semiconductor diode that produces a significant current when illuminated. It is reversed biased but is operated below the breakdown voltage.
Energy of radiation $=$ band gap energy ie, $h v=2.0 \mathrm{eV}$
$$
\text { or } v=\frac{2.0 \times 1.6 \times 10^{-19}}{6.6 \times 10^{-34}} \approx 5 \times 10^{14} \mathrm{~Hz}
$$

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