In extrinsic $P$ and $N$-type semiconductor materials,the ratio of the impurity atoms to the pure semiconductor atoms is about

$N-$ type semiconductors are obtained when germanium is doped with:

In a pure silicon $(n_i = 10^{16}/m^3)$ crystal at $300\, K$,$10^{21}$ atoms of phosphorus are added per cubic meter. The new hole concentration will be

$A$ $P$-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 $h = 6.6 \times 10^{-34} \, J-s$, speed of light $c = 3 \times 10^8 \, m/s$, charge of electron $e = 1.6 \times 10^{-19} \, C$)

Which of the following statements is true for an $N$-type semiconductor?

Let ${n_h}$ and ${n_e}$ be the number of holes and conduction electrons respectively in a semiconductor. Then