A sample of silicon is doped with 1.5 × 10⁵ arsenic atoms/c.c. If the intrinsic carrier density in silicon at 300 K is 1.5 × 10¹⁰/ cc, the electron density and hole density in the sample:

New electron concentration after doping is given by:

${\mathrm{n}}_{\mathrm{e}}\text{'} = {\mathrm{n}}_{\mathrm{e}} + {\mathrm{n}}_{\mathrm{i}}$

$\Rightarrow {\mathrm{n}}_{\mathrm{e}}\text{'} = 1.5 \times {10}^5 + 1.5\times {10}^{10} \approx 1.5\times {10}^{10}\approx {\mathrm{n}}_{\mathrm{i}}$

Since amount of substance being doped is less, therefore electron and hole density in the semiconductor will be equal to intrinsic charge carrier density.

I.e. ${\mathrm{n}}_{\mathrm{e}} = {\mathrm{n}}_{\mathrm{h}} = {\mathrm{n}}_{\mathrm{i} }= 1.5 \times {10}^{10}$

And it will behave as intrinsic.