Question

A silicon specimen is made into a P-type semi-conductor 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/m³, then the number of acceptor atoms in silicon will be

• A. (a) $2.5 \times 10^{30}$ atoms/cm³
• A. (b) $1.0 \times 10^{13}$ atoms/cm³
• A. (c) $1.0 \times 10^{15}$ atoms/cm³
• A. (d) $2.5 \times 10^{36}$ atoms/cm³

Answer 1

(c)

Number density of atoms in silicon specimen = 5 × 10²⁸ atom/m³ = 5 × 10²² atom/cm³

Since one atom of indium is doped in 5 × 10⁷ Si atom. So number of indium atoms doped per cm^‑3 of silicon.

$n = \frac{5 \times 10^{22}}{5 \times 10^{7}} = 1 \times 10^{15}atom/cm^{3}.$