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The number density of electron is a semi...

The number density of electron is a semiconductor is `8xx10^(13) cm^(-3)` and number density of hole is `5xx10^(12) cm^(-3)` then,
(1) Which type of this semiconductor is?
(2) How much is resistivity of it? (Mobility of electron is 23000 `cm^(2)V^(-1)s^(-1)` and mobility of hole is 100 `cm^(2)V^(-1)s^(-1) and e=1.6xx10^(-19)C`)

Text Solution

Verified by Experts

`n_(e )=8xx10^(13)cm^(-3)=8xx10^(19)m^(-3)`
`n_(h)=5xx10^(12)cm^(-3)=5xx10^(18)m^(-3)`
`mu_(e )=23000cm^(2)V^(-1)s^(1)=2.3m^(2)V^(-1)s^(-1)`
`mu_(h)=100cm^(2)V^(-1)s^(-1)=0.01m^(2)V^(-1)s^(-1)`
Here number density of electron is more that holes therefore semiconductor is of n type `(n_(e ) gt n_(h))`
`sigma=(1)/(rho)=e(n_(e )mu_(e )+n_(h)mu_(h))`
`=1.6xx10^(-19)[8xx10^(19)xx2.3+5xx10^(18)xx0.01]`
`=1.6xx10^(-19)[1.84xx10^(20)+5xx10^(16)]`
`(1)/(rho) ~~29.45 "mho m"^(-1)`
`therefore rho=(1)/(29.45)=3.396xx10^(-2)` ohm m
`therefore rho=3.396xx10^(-2)Omegam`
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