In an extrinsic semiconductor,the number densities of holes and electrons are ${N_p}$ and ${N_e}$ respectively. Then:

$A$ $P$-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 $e = 1.6 \times 10^{-19} \, C$)

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

Pure $Si$ at $500\, K$ has equal number of electron $(n_e)$ and hole $(n_h)$ concentrations of $1.5 \times 10^{16} \, m^{-3}$. Doping by indium increases $n_h$ to $4.5 \times 10^{22} \, m^{-3}$. The doped semiconductor is of:

For extrinsic semiconductors,when the doping level is increased:

$A$ silicon specimen is made into a $p$-type semiconductor by doping,on an average,one indium atom per $5 \times 10^7$ silicon atoms. If the number density of atoms in the silicon specimen is $5 \times 10^{28} \text{ atoms } m^{-3}$,then the number of acceptor atoms in silicon per cubic centimeter will be: