Pure `Si` at `500K` has equal number of electron `(n_(e))` and hole `(n_(h))` concentration of `1.5xx10^(16)m^(-3)`. Dopping by indium. Increases `n_(h)` to `4.5xx10^(22) m^(-3)`. The doped semiconductor is of

Options

A. p-type having electron concentration `n_(e) = 5 xx 10^(9) m^(-3)`
B. h-type with electron concentration `n_(e) = 5 xx 10^(22) m^(-3)`
C. p-type with electron concentration `n_(e) = 2.5 xx 10^(10) m^(-3)`
D. n-type with electron concentration `n_(e) = 2.5 xx 10^(23) m^(-1)`

Answer

A

Explanation

p - type semiconductor is obtained when Si or Ge is doped with a trivalent impurity like aluminium (Al), boron (B ), indium (In) etc.
Here, `n_(i)=1.5xx10^(16)m^(-3), n_(h)=4.5xx10^(22)m^(-3)`
`"As "n_(e)n_(h)=n_(i)^(2)`
`n_(e)=(n_(i)^(2))/(n_(h))=((1.5xx10^(16)m^(-3))^(2))/(4.5xx10^(22)m^(-3))=5xx10^(9)m^(-3)`