Question

The maximum wavelength of electromagnetic radiation, which can create a hole-electron pair in germanium. (Given that forbidden energy gap in germanium is $0.72\, eV$)

• A. $1.7 \times 10^{-6}m$
• B. $1 .5 \times 10 ^{-5}m$
• C. $1.3 \times 10^{-4} m$
• D. $1.9 \times 10^{-5} m$

Answer 1

Answer: (A)

Here, $E_g = 0.72\, eV$
$ = 0.72 \times 1.6 \times 10^{-19}\, J$
If $\lambda$ is the maximum wavelength of electromagnetic radiation which can create a hole-electron pair in germanium, then
$E_g = \frac{hc}{\lambda}$
or $\lambda = \frac{hc}{E_{g}} $
$ =\frac{6.62\times 10^{-34}\times 3\times 10^{8}}{0.72\times 1.6\times10^{-19}}$
$= 1.7\times 10^{-6}m$