Q. A photodetector is made from a semiconductor with $E_{g} = 0.73\ eV$. What is the maximum wavelength, which it can detect
A) 1000 $nm$
B) 1703 $nm$
C) 500 $nm$
D) 173 $nm$
Explanation
(b) Limiting value of $hv$ is $E_{g}$, such that $hv = \frac{hc}{\lambda} = E_{g}$
or $\lambda = \frac{hc}{E_{g}} = \frac{6.63 \times 10^{- 34}J - s \times 3 \times 10^{8}ms^{- 1}}{0.73 \times 1.6 \times 10^{- 19}\ J}$
$= 1703\ nm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.