A semiconductor has equal electron and hole concentration of `2 xx 10^(8) m^(-3)`. On doping with a certain impurity, the eletron concendration increases to `4 xx 10^(10) m^(-3)`, then the new hole concentration of the semiconductor is

Options

A. `10^6 m^(-3)`
B. `10^(8) m^(-3)`
C. `10^(10)m^(-3)`
D. `10^(12)m^(-3)`

Answer

A

Explanation

`eta_(e) =2xx 10^(8)m^(-3), eta_(h)=2xx10^(8)m^(-3)`
New electron concentration, `eta_(e)=4xx10^(10)m^(-3)`
`eta_(e) xx eta_(h)= eta^(2)`
`eta_(e) xx eta_(h)=eta_(e) xx eta_(n)`
`eta_(eta)=(eta_e xx eta_ n)/(eta_e)=(2xx10^8 xx2xx10^8)/((4xx10^10)/(m^3))`
`=(10^(16-10))/(m^3)`
`=(10^0)/(m^3)`
`eta_eta=10^6 m^(-3)` .