JEE MAIN - Physics (2021 - 25th July Evening Shift - No. 25)
In a semiconductor, the number density of intrinsic charge carries at 27$$^\circ$$C is 1.5 $$\times$$ 1016/m3. If the semiconductor is doped with impurity atom, the hole density increases to 4.5 $$\times$$ 1022/m3. The electron density in the doped semiconductor is ___________ $$\times$$ 109/m3.
Answer
5
Explanation
$${n_e}{n_h} = {n_i}^2$$
$${n_e} = {{{n_i}^2} \over {{n_h}}} = {{{{(1.5 \times {{10}^{16}})}^2}} \over {4.5 \times {{10}^{22}}}}$$
$$ = {{1.5 \times 1.5 \times {{10}^{32}}} \over {4.5 \times {{10}^{22}}}}$$
$$ = 5 \times {10^9}$$/m3
$${n_e} = {{{n_i}^2} \over {{n_h}}} = {{{{(1.5 \times {{10}^{16}})}^2}} \over {4.5 \times {{10}^{22}}}}$$
$$ = {{1.5 \times 1.5 \times {{10}^{32}}} \over {4.5 \times {{10}^{22}}}}$$
$$ = 5 \times {10^9}$$/m3
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