The impurity atom added to germanium to make it $N-$type semiconductor is

The acceptor level of a $p$-type semiconductor is $6 \ eV$ above the valence band. The maximum wavelength of light which can create a hole would be: (Given $hc = 1242 \ eV \ nm$) (in $nm$)

If $n_{e}$ and $n_{h}$ are concentrations of electrons and holes in a semiconductor,then the intrinsic carrier concentration $(n_i)$ in thermal equilibrium is

$A$ pure $Si$ crystal has $5 \times 10^{28}$ atoms $m^{-3}$. It is doped with $1 \, ppm$ concentration of pentavalent $As$. The number of holes is (Take $n_i = 1.5 \times 10^{16} \, m^{-3}$)

When a small amount of impurity atoms are added to a semiconductor,then generally its resistivity:

The electron concentration in an $n$-type semiconductor is the same as the hole concentration in a $p$-type semiconductor. An external electric field is applied across each of them. Compare the currents in them.