Browse Questions

A p type semiconductor has acceptor level of 50 mev above the valance band. Find the maximum wave length of light which can create a hole.

$(a)\;1.28 \times 10^{-5} m \\ (b)\;2.48 \times 10^{-5}\;m \\ (c)\;1.56 \times 10^{-5} m \\ (d)\;3.62 \times 10^{-5}m$

To create a hole an electron must be given energy at least equal to 50 mev to go into acceptor level.
$\large\frac{hc}{\lambda}$$\geq\; 50 mev$
$\lambda \geq \large\frac{hL}{50 mev}$
$\qquad= \large\frac{1242 ev\;nm}{50 \times 10^{-3} ev}$
$\qquad= 2.48 \times 10^{-5} \;m$
Hence b is the correct answer.
edited Jul 13, 2014