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# A P-n junction is fabricated from a semiconductor with band gap of $2.8\;ev$ can it detected a wavelength of $600\;nm$?

$\begin{array}{1 1} \text{ can detect} \\ \text{Cannot detect } \\ \text {given data is not determined } \\ \text{none of the above }\end{array}$

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A)
Solution :
$E= \large\frac{hc}{\lambda}$
$\qquad= \large\frac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{600 \times 10^{-9} \times 1.6 \times 10^{-19}}$$ev$
$\qquad= 2.06\;ev < 2.8ev$
$=> E< E_g$
Hence p-n junction cannot detect the radiation of given wavelength