Realizing bulk and surface attributes driven third order nonlinear optical traits of ZnO layers for optical limiting operation; A thickness and impurity dependent investigation

Abstract

The intrinsic, aluminium doped and gallium doped ZnO thin films with one, three and five layers of gradience have been successfully deposited using sol-gel spin coating method. Optical investigations were performed to analyze the linear as well as the nonlinear characteristics of the material along with its optical limiting caliber. The structural and morphological evaluations were also carried out to examine the bulk and surface properties of the samples. It is found that both dopant type and thickness have an independent effect on the structure, morphology, and optical features of the thin films. The surface traits have turned out to be significant along with the bulk properties to make the nonlinear absorption coefficient of the five-layered gallium doped ZnO thin film enhanced. Whereas, the improved crystallinity has been found to lower the optical limiting threshold of the specimens. The five-layered gallium doped ZnO has been evidenced as an optimized material for optical limiting applications with nonlinear absorption coefficient of 1.10 x 10–8 cm/W and an optical limiting threshold of 7.11 x 1012 W/m2.