$A$ pure $Si$ crystal has $4 \times 10^{28}$ atoms per $m^3$. It is doped with $1 \text{ ppm}$ concentration of antimony. The number of free electrons available will be

In $N$-type semiconductors,the majority charge carriers are

Which statement is correct for a $p$-type semiconductor?

In a semiconductor,the concentrations of electrons and holes are $8 \times 10^{18} \, m^{-3}$ and $5 \times 10^{18} \, m^{-3}$ respectively. If the mobilities of electrons and holes are $2.3 \, m^2/V \cdot s$ and $0.01 \, m^2/V \cdot s$ respectively,then the semiconductor is:

Pure Silicon crystal at $300 \ K$ has equal electron and hole concentration of $1.5 \times 10^{16} \ m^{-3}$. Doping by indium increases $n_h = 4.5 \times 10^{22} \ m^{-3}$. The $n_e$ in the doped silicon is:

In a $p$-type semiconductor,the acceptor level is at $50 \text{ meV}$ above the valence band. To produce one hole,the maximum wavelength of the light photon required is (Planck's constant,$h = 6.6 \times 10^{-34} \text{ Js}$ and speed of light in vacuum,$c = 3 \times 10^8 \text{ m/s}$) (in $\mu \text{m}$)