Question

Due to illumination by light, the electron and hole concentrations in a heavily doped $N$ type semiconductor increases by $\Delta n$ and $\Delta p$ respectively if $n_i$ is the intrinsic concentration then,

• A. $\Delta n=\Delta p$
• B. $\Delta n<\Delta p$
• C. $\Delta n\times \Delta p=n_i^2$
• D. $\Delta n>\Delta p$

Answer 1

The correct option is A $\Delta n=\Delta p$

Ans :(c)
Before illumination by light,N Type of Semiconductor is electrically neutral i.e. it has equal number of positive and negative ions ,after illumination band to band transition happens which leads to equal number of electrons and holes generation .
Hence ,
$\Delta n=\Delta p$
Due to illumination by light EHP (electron -hole pair) generation occurs,
Where
$\Delta n$= increase in electron concentration due to illumination by light
$\Delta p$ = increase in hole concentration due to illumination by light