Question

The intrinsic carrier concentration of silicon sample at $ 300\, K $ is $ 1.5 \times 10^{16}\, m^{-3} $ . What is the density of minority carrier ? (after doping, the number of majority carriers is $ 5 \times 10^{20}\, m^{-3} $ )

• A. $ 4.5 \times 10^{11}\,m^{-3} $
• B. $ 3.3 \times 10^{4}\,m^{-3} $
• C. $ 5 \times 10^{20}\,m^{-3} $
• D. $ 3 \times 10^{-5}\,m^{-3} $

Answer 1

Answer: (A)

$n_{i}=1.5\times10^{16} m^{-3}; $
$n_{o}=5\times10^{20} m^{-3}$
$p_{o}=\frac{n_{i}^{2}}{n_{o}}=\frac{\left(1.5\times10^{16}m^{-3}\right)^{2}}{5\times10^{20} m^{-3}}$
$=4.5\times10^{11} m^{-3}$