Semiconductor Devices And Logic Gates

The concentration of electrons in an intrinsic semiconductor is $6 \times 10^{15} \mathrm{~m}^{-3}$. On doping with an impurity, the electron concentration increases to $4 \times 10^{22} \mathrm{~m}^{-3}$. In thermal equilibrium, the concentration of the holes in the doped semiconductor is