• # question_answer Pure silicon at 300 K has equal electron ne and hole $({{n}_{h}})$ concentration of $1.5\,\,\times \,\,{{10}^{16}}\,{{m}^{-}}^{3}$. Doping by indium increases ${{n}_{h}}$ to $4.5\,\,\times \,\,{{10}^{22}}\,{{m}^{-}}^{3}$. The ${{n}_{e}}$ in the doped silicon is (in per ${{m}^{3}}$)- A) $9\,\,\times \,\,{{10}^{5}}$                 B) $5\times {{10}^{9}}$C) $2.25\times {{10}^{11}}$                   D) $3\times {{10}^{19}}$

${{n}_{i}}=1.5\times {{10}^{16}}$ ${{n}_{h}}=4.5\times {{10}^{22}}$ $Law\,\,of\text{ }mass\text{ }action\text{ }{{n}_{e}}{{n}_{h}}=n_{i}^{2}$ ${{n}_{e}}=\,\,\frac{n_{i}^{2}}{{{n}_{h}}}\,\,=\,\,\frac{{{(1.5\times {{10}^{16}})}^{2}}}{(4.5\times {{10}^{22}})}$ ${{n}_{e}}\,\,=\,\,5\times {{10}^{9}}\,\left( \frac{1}{{{m}^{3}}} \right)$