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)`
The number of electrons in this semiconductor are

Options

A. `5.0xx10^(15)`
B. `4.95xx10^(15)`
C. `4.95xx10^(22)`
D. `25xx10^(22)`

Answer

B

Explanation

Number density of electrons,
`n_(e)=5xx10^(22)-5xx10^(20)=4.95xx10^(22)m^(-1)`
Number of electrons in the given semiconductor
`=n_(e)xxvolume`
`=4.95xx10^(22)xx(1/100xx1/100xx1/1000)`
`=4.95xx10^(15)`