In an intrinsic semiconductor, the energy gap `E_(g)` of an intrinsic semiconductor is 1.2 eV. Its hole mobility is very much smaller than electron mobility and is indepndent of temperature. What is the ratio between conductivity at 600K and at 300K? Assume that the temperature dependence of intrinsic concentraction `n_(i)` is expressed as,
`n_(i)=n_(o)e^(-E_(g)^(')//k_B)T`, where `n_(o)` is constant and `E_(g)^(')` is an energy equal to `E_(g)//2`,
`k_(B)=8.62xx10^(-6)eVK^(-1)`.

Explanation

Since `mu_(e) gt mu_(H)` and for the intrinsic semiconductor `n_(e) = n_(h) = n_(1)` can be written as
`sigma = emu_(e) n_(e)`
All the pre -exponential tems are assumed indpendent of temperature .We can put a constant
`sigma = emu_(e) n_(0)`
and express the conductivity
Now `sigma (600 K) = sigma ex p [ (-1.2)/( 2k_(b) xx 600) ]`
This show that the conductivity of an intrinsic semi - conductor is greatly influenced by temperature .