The energy of a photon of sodium light wavelength `5890 Å` equals the energy gap of a semiconducting material. Find the minimum energy E required to create a hole-electron combination. the value of `E//kT` at a temperature of `27^(@)C`, where `k=8.62xx10^(-5) eV//K, h=6.63xx10^(-34)Js`.

Explanation

Energy required to create a hole-electron combination is equal to energy E of photon which can push an electron from valence band to conduction band.
Thus `E=(hc)/lambda=(6.63xx10^(-34)xx3xx10^(8))/(5890xx10^(-10)xx1.6xx10^(-19))`
`=2.1eV`
Here `T=27^(@)C=273+27=300K`
`:. E/(KT)=(2.1)/(8.62xx10^(-5)xx300)=81.2`