Question

The contribution in the total current flowing through a semiconductor due to electrons and holes are $\frac{3}{4}$ and $\frac{1}{4}.$ If the drift velocity of the electron is $\frac{5}{2}$ times that of holes at this temperature, then the ratio of concentration of electrons and holes is

• A. $6:5$
• B. $5:6$
• C. $3:2$
• D. $2:3$

Answer 1

The correct option is A $6:5$

As we know current density $J=nqv$

$\Rightarrow J_e=n_{e}q{v}_e$ and $J_h=n_{h}q{v}_h$

$\Rightarrow \frac{J_e}{J_h}=\frac{n_e}{n_h}\times \frac{v_e}{v_h}\Rightarrow \frac{3/4}{1/4}=\frac{n_e}{n_h}\times \frac{5}{20}\Rightarrow \frac{n_e}{n_h}=\frac{6}{5}$