Problem $5$

$($a$)$ Assume that an n$-$type semiconductor is uniformly illuminated, producing a uniform excess generation rate $g^{\text{'}}.$ Show that in steady state the change in the semiconductor conductivity $($also called photoconductivity$)$ is given by:

$=q*({}_n+{}_p)*{}_{po}*g^{\text{'}}$

$($b$)$ Calculate the value of $$ and hence of the induced photocurrent for the following parameters: ${}_n=2500\frac{c{m}^2}{V(s)},{}_p=540\frac{c{m}^2}{V(s)},{}_{po}=10s,g^{\text{'}}=2{10}^{14}\frac{c{m}^{-3}}{(s)},=50\frac{(V)}{(cm)}.$

$($c$)$ If the semiconductor is p$-$type how would you write the expression for the photoconductivity?