A semiconductor has an electron concentration of `8xx10^(13)` per `cm^(3)` and a hole concentration of `5xx10^(12)` per `cm^(3)`. The electron mobilityis `25,000 cm^(2)V^(-1)sec^(-1)` and the hole mobility is `100cm^(2)V^(-1)sec^(-1)` and the hole mobility is `100cm^(2)V^(-1)sec^(-1)`
(i) The semiconductor is `n`-type
(ii) the semiconductor is `p`-type
(iii) the conductivity is `320m mho cm^(-1)`
(iv) the conductivity is `80m mho cm^(-1)`

Options

A. `(i)(iii)`
B. `(ii),(iii)`
C. `(i),(iv)`
D. (ii),(iv)`

Answer

A

Explanation

`n_(e)=8xx10^(13)//cm^(3),n_(h)=5xx10^(12)//cm^(3)`
`mu_(e)=25000cm^(2)V^(-1)sec^(-1), mu_(h)=100cm^(2)V^(-1)sec^(-1)`
`sigma=n_(e)mu_(e)e+n_(h)mu_(e)e`
`=(8xx10^(13)xx25000+5xx10^(12)xx100)xx1.6xx10^(-19)`
`=320xx10^(-3)m mho//cm`
`n_(e)gtn_(h)(n-type)`