The band gap between the valence and the conduction bands in zinc oxide (ZnO) is 3.2 eV. Suppose an electron in the conduction band combines with a hole in the valence band and the excess energy is released in the form of electromagnetic radiation. Find the maximum wavelength that can be emitted in this process.


For the electron to move from the conduction band to valance band it will have to loose energy same as the energy band gap of ZnO, i.e., 3.2.


The energy lost is in the form of electromagnetic radiation, for which the energy is given as following,



where,


,



is the wavelength




1