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

Explanation

In pure semiconductor electron-hole `n_(1)=10^(19) m^(-3)` acceptor impurity `N_(A) = 10^(21) m^(-3)`
Holes concentration `n_(h) = 10^(21) m^(-3)`
Electrons concentration `= n_(e) = (n_(1)^(2))/(n_(h)) = ((10^(19))^(2))/(10^(21))=10^(17)m^(-3)`.