Preparation of ZnO thin films as an effective medium for random lasers and study of their structural and optical properties

Abstract

Thin films of ZnO were successfully prepared on glass substrates with different thicknesses by sol-gel method by using zinc acetate dehydrate as precursor. The surface of thin films morphology from were studied by AFM micrographs, the structural properties of the obtained ZnO thin film are studied using X-ray diffraction spectra and their elemental analysis by X-ray energy dispersion spectroscopy (EDX). Moreover, optical properties and emission of ZnO nano thin film were studied using spectrophotometer and photoluminescence spectra. The AFM investigations have revealed that the morphology of the films is smooth and homogeneous specially for the high thickness and the grains produced on the surface take the form of nano rods with an average diameter of 240nm. Structural analysis by X-ray diffraction showed that the deposited films have a preferred orientation along the direction (112) and are relatively uniform with average crystal size 19nm, while the EDX spectrum showed that the elemental composition of these films is zinc oxide. The optical spectra of prepared films confirm that it is possible to get good transparent ZnO films with a transmission of 77 to 92% in the visible and infrared. The values of optical gaps Eg vary between 3.273 - 3.256 eV. The peak of photoluminescence exhibited a visible emission peaks at 616nm and 648nm that refers to possibility of using thin films as an effective medium of random laser.