Question

A silicon specimen is made into a$P-$type semiconductor by doping, on an average, one Indium atom per $5\times {10}^7$silicon atoms. If the number density of atoms in the silicon specimen is$5\times {10}^{28}{\text{per m}}^3$. Then the number of acceptor atoms in silicon per cubic centimetre will be,

• A. $2.5\times {10}^{30}{\text{per cm}}^3$
• B. $1.0\times {10}^{13}{\text{per cm}}^3$
• C. $1.0\times {10}^{15}{\text{per cm}}^3$
• D. $2.5\times {10}^{36}{\text{per cm}}^3$

Answer 1

The correct option is C $1.0\times {10}^{15}{\text{per cm}}^3$

Number density of atoms in silicon specimen $=5\times {10}^{28}{\text{per m}}^3=5\times {10}^{22}{\text{per cm}}^3$

As one Indium atom is doped in $5\times {10}^7$ silicon atoms, so the number of Indium atoms doped per ${\text{cm}}^3$ of silicon is,
$n=\frac{5\times {10}^{22}}{5\times {10}^7}={10}^{15}{\text{per cm}}^3$

Hence, $\left(C\right)$ is the correct answer.