Define drift current, diffusion current and P-N junction. The electrical conductivity of a pure silicon at room temperature is $4×10^{(-4)}$mho/m . if the mobility of electron is $0.14m^2/V-S$ and that of hole is $0.04m^2/V-S$.

DRIFT CURRENT :-

Drift current is the electric current, or movement of charge carriers, which is due to the applied electric field, often stated as the electromotive force over a given distance.

DIFFUSION CURRENT:-

Diffusion current is a current in a semiconductor caused by the diffusion of charge carriers. This is the current which is due to the transport of charges occurring because of nonuniform concentration of charged particles in a semiconductor.

P-N JUNCTION:-

A diode is a PN junction with p-type on one side and n-type on the other. When a positive voltage is applied to the p-type side , it shrinks and overcomes the depletion zone, causing the current flow from the p-type to the n-type side.

NUMERICAL:-

Given Data :-$ σ=4×10^{(-4)}mho/m ,\hspace{1cm} μ_e=0.14m^2/V-sec , \hspace{1cm} μ_h = 0.04m^2/V-S$

Formula :- $σ_i= n_i (μ_e+ μ_h ).e$

Calculations :- $ n_i = σ_i/((μ_e+ μ_h ).e)$

=$ (4×10^{(-4)})/(1.6×10^{(-19)} (0.14+0.040))$

$n_i = 1.388 ×10^{16}/m^3$

Answer :- carrier concentration = $1.388 ×10^{16}/m^3$