Electronic excitation induced anomalous band gap enhancement in NixCd1-xO thin films

Abstract

The effect of swift heavy ion(SHI) (Ag, O ion) irradiation on structural, electrical, optical properties, electron-LO phonon interaction and orbital hybridization for Ni doped CdO (NDO) based thin films has been thoroughly investigated in the present manuscript. The anomalous band gap enhancement has been explained in the frame work of electron-electron interaction, electron-impurity interaction, electron–phonon interaction and p-d hybridization between O 2p and Cd/Ni d orbitals for (NDO). The carrier concentration increment via generation of oxygen vacancies further enhances the aforementioned interaction but weakens the electron-LO phonon coupling due to screening among free carriers which counter renormalizes the band gap modification. The tensile strain observed from XRD pattern enhances the p-d hybridization which will enhance the band edge electron effective mass and subsequently the band gap. An energy band diagram has been developed to substantiate the same. However the study of the effect of EEs on hybridization is rare in the literature. Thus it emerges out to be very fascinating for the in-depth understanding of fundamental interaction besides their possible potential applications in the flourishing of optoelectronic industry.