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 $5 \times 10^{28}$ atoms/ $m ^{3}$, then the number of acceptor atoms in silicon per cubic centimetre will be

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

Answer 1

Answer: (C)

Number density of atoms in silicon specimen
$=5 \times 10^{28}$ atom $/ m ^{3}=5 \times 10^{22} / cm ^{3}$
Since one atom of indium is doped in $5 \times 10^{7}$ Si atom, so number of indium atoms doped per $cm ^{3}$ of silicon.
$n=\frac{5 \times 10^{22}}{5 \times 10^{7}}=1 \times 10^{15}$ atom $/ cm ^{3}$