A piece of pure semiconductor of silicn of size `1cm xx 1 cm xx 1 mm` is having `5 xx 10^(28)` number of atoms per cubic metre. It is doped simultaneously with `5 xx 10^(22)` atoms per `m^(3)` of aresenic adn `5 xx 10^(20)` per `m^(3)` atoms of indium. The number density of intrisic current carrier (electrons adn holes) in the pure silicon semiconductor is `1.5 xx 10^(16) m^(-3)`. Mobility of electron is `3800 cm^(2) V^(-)S^(-1)`
Ratio of conductivity of doped silicon and pure silicon semiconductor is

Options

A. `2.2xx10^(6)`
B. `3.3xx10^(6)`
C. `2.2xx10^(8)`
D. `3.3xx10^(8)`

Answer

B

Explanation

Ratio of the conductivity of doped silicon and pure silicon semiconductor is
`(sigmad)/sigma_(i)=n/n_(i)=(4.95xx10^(22))/(1.5xx10^(16))=3.3xx10^(6)`