A semiconductor is known to have an electron concentration of `8 xx 10^(13) cm^(-3)` and a hole concentration of `5 xx 10^(12) cm^(-3)` .
a . Is the semiconductor n- type of p-type ?
b. What is the resistitivity of the simple , if the electron mobility is 23,000 `cm^(2) V^(-1) s^(-1)` and hole mobility is `100 cm^(2) V^(-1) s^(-1)` ? Take charge on electron , `e = 1.6 xx 10^(-19)` C .

Explanation

Data supplied ,
`n_(e) = 8 xx 10^(13) cm^(-3) = 8 xx 10^(19) m^(-3)`
`n_h = 5 xx 10^2 cm^(-3) = 5 xx 10^(18) m^(-3)`
`mu_(e) = 23,000 cm^(2) V^(-1) s^(-1) = 2.3 m^(2) V^(-1) s^(-1)`
`mu_(h) = 100 cm^(2) V^(-1) s^(-1) = 0.01 m^(2) V^(-1) s^(-1)`
a. Here semiconductor has greater electron concentration . So it is n- type semiconductor .
b. `(1)/(rho) = e(n_(e) mu_(e) + n_(h) mu_(h)) = 1.6 xx 10^(-19) (8 xx 10^(19) xx 2.3 + 5 xx 10^(18) xx 0.1) = 30 m ho m^(-1)`
`rho = (1)/(30) = 3.3 xx 10^(-2) Omega m`