Answer to Question #134669 in Electric Circuits for ROHIT

Question

A sample of Si has electron and hole mobilities of 0.13 and 0.05 m /V-s 2 respectively at
300 K. It is doped with P and Al with doping densities of 21 3 1.510 / m and
21 3 2.510 / m respectively. The conductivity of the doped Si sample at 300 K is

Answer 1

As per Question,

for electron' mobility $\mu_e=0.13$

for holes

mobility $\mu_h=0.05$

Concentration of Phosphorus atom i.e.

Donor concentration $N_D=n=1.5\times10^{10}/m^3$

Concentration of Aluminum atom i.e.

Acceptor impurities concentration $N_A=p=2.5\times 10^{10}/m^3$

Conductivity

$\sigma=q(n\mu_e+p\mu_p)$

=$1.6\times 10^{-19}(1.5\times10^{10}\times0.13+2.5\times10^{10}\times0.05)$

=$1.6\times10^{-9}(0.195+0.125)$

=$1.6\times10^{-9}\times0.320$

=0.512$\times10^{-9}$

$=5.12\times10^{-8}$ $\Omega^{-1}$