A pure Si crystal having 5 × 10^28 atoms m^-3 is dopped with 1 ppm concentration of antimony. If the concentration of holes in the doped crystal is…

A pure Si crystal having $\displaystyle 5 \times 10^{28}$ atoms $\displaystyle \mathrm{m}^{-3}$ is dopped with $\displaystyle 1$ ppm concentration of antimony. If the concentration of holes in the doped crystal is found to be $\displaystyle 4.5 \times 10^{9} \mathrm{~m}^{-3}$, the concentration (in $\displaystyle \mathrm{m}^{-3}$ ) of intrinsic charge carriers in Si crystal is about