Tuning the third-order nonlinear optical properties of In: ZnO thin films by 8 MeV electron beam irradiation

We report the third-order nonlinear optical properties of electron beam treated Indium doped ZnO (Zn_1-xIn_xO (x = 0.03) thin films at different dose rate. Zn_1-xIn_xO (x = 0.03) thin films prepared by spray pyrolysis deposition technique were irradiated using 8 MeV electron beam at dose rates ranging from 1 kGy to 4 kGy. X-ray diffraction patterns were obtained to examine the structural changes, The transformation from sphalerite to wurtzite structure of ZnO was observed which indicates occurrence of structural changes due to irradiation. Morphology of irradiated thin films examined using atomic force microscopy (AFM) technique indicates the surface roughness varying with irradiation dose rate. The switching over from Saturable Absorption (SA) to Reverse Saturable Absorption (RSA) behaviour was noted when the irradiation dose rate was increased from 1 kGy to 4 kGy. The significant changes observed in the third-order nonlinear optical susceptibility χ(3) of the Zn_1-xIn_xO (x = 0.03) thin films is attributed mainly due to electron beam irradiation. The study indicates that nonlinear optical parameters can be controlled by electron beam irradiation by choosing appropriate dose rate which is very much essential for device applications. Hence Zn_1-xIn_xO (x = 0.03) materialize as a promising material for use in nonlinear optical device applications.