A `Ge` specimen is dopped with `Al`. The concentration of acceptor atoms is `~10^(21) at oms//m^(3)`. Given that the intrinsic concentration of electron hole pairs is `~10^(19)//m^(3)`, the concentration of electron in the speciman is

Options

A. `10^17//m^3`
B. `10^15//m^3`
C. `10^4//m^3`
D. `10^2//m^3`

Answer

A

Explanation

Germanium doped with Aluminium (trivalent impurity) produces a p-type semiconductor in which `n_h=10^21` atoms/`m^3` (acceptor atoms)
`because n_h n_e = n_1^2`
`therefore n_e=n_i^2/n_h =(10^19xx10^19)/10^21 = 10^17 ` atoms/`m^3`