A semiconductor har equaI eIectron and hoIe concentrations of `6 xx 10^(8)"m"^(-3)` . On doping with a certain impurity,the eIectron concentration of the semiconductor increases to `8 xx 10^(12)"m"^(-3)` . (i) What type of semiconductor is obtained on doping? (ii) CaIcuIate the new hoIe concentration of the semiconductor.

Explanation

Here ,n = P =`n_(i)=6 xx 10^(8) "m" ^(-3)` i.e in initial state it is an intrinsic semiconductor.
(i) As the concentration of electrons as majority carriers increases on doping so n-type semiconductor is formed .
(ii) In n-type semiconductor the electron concentration
n =`8xx 10^(12) "m"^(-3)`
Here np =` n_(i)^(2)`
Therefore the new hole concentration,
P=`(n_(i)^(2))/(n)=(6xx10^(8))^(2)/(8xx10^(12))=4.5 xx10^(4)"m"^(-3)`