An intrinsic semiconductor is converted into $N$-type extrinsic semiconductor by doping it with

In which of the following statements is the obtained impure semiconductor of $p$-type?

Holes are charge carriers in

In a semiconductor,the concentration of electrons is $8 \times 10^{14} \text{ cm}^{-3}$ and that of the holes is $5 \times 10^{12} \text{ cm}^{-3}$. The semiconductor is

$A$ $P$-type semiconductor has acceptor levels $57 \; meV$ above the valence band. The maximum wavelength of light required to create a hole is (Planck's constant $h = 6.6 \times 10^{-34} \; J \cdot s$, speed of light $c = 3 \times 10^8 \; m/s$)

If the ratio of electron and hole currents in a semiconductor is $\frac{7}{4}$ and the ratio of drift velocities of electrons and holes is $\frac{5}{4}$, then the ratio of concentrations of electrons and holes will be