Pure silicon at $300 \mathrm{K}$ has equal electron and hole concentration of $1.5\times {10}^{16} {\mathrm{m}}^{-3}$. Doping by indium increases the hole concentration to $4.5\times {10}^{22} {\mathrm{m}}^{-3}.$ Calculate the new electron concentration in the doped silicon.

A semiconductor has equal electron and hole concentrations of  $6\times {10}^8 {\mathrm{m}}^{-3}$. On doping with certain impurity, electron concentration increases to $9 \mathrm{x} {10}^{12} {\mathrm{m}}^{-3}$. Identify the new obtained after doping.

A semiconductor has equal electron and hole concentrations of  $6\times {10}^8 {\mathrm{m}}^{-3}$. On doping with certain impurities, electron concentration increases to $9 \mathrm{x} {10}^{12} {\mathrm{m}}^{-3}$. Calculate the hole concentration.