To create a hole an electron must be given energy at least equal to 57 mev to go into acceptor level.

$\large\frac{hc}{\lambda}$$ \geq\; 57 mev$

$\lambda \geq \large\frac{hL}{57 mev}$

$\qquad= \large\frac{1242 ev\;nm}{57 \times 10^{-3} ev}$

$\qquad= 2.18 \times 10^{-5} \;m$