Effect of annealing by CO2 laser on Structural and optical properties of zinc oxide thin films prepared by Sol – gel method

Abstract

Laser heat treatment is one of the important industrial applications of laser and being studied at the present time as a substitute for conventional thermal annealing. In this research (ZnO) thin films have been deposition on a glass by (Sol - Gel / Spin Coating) technique and annealed by two ways, the first one using a convection oven, where they were annealing with three temperatures (400, 500, 600) °C for one hour, and the second way using a continuous (CO₂) laser with (10.6 μm) wavelength and (10 W) power and three intervals (10, 15, 20) min, were studied structural and optical properties of membranes prepared by both ways to determine the effect of laser annealing on them, and the results of (XRD) tests showed that these membranes with the structural of multi-crystalline hexagon compact type and increase the degree of temperature oven annealing, as well as increasing the duration of the laser annealing lead to increased volumes of granular membranes rates. The results of the (AFM) tests to the topography of the surfaces of the membranes to be of crystalline uniformity and homogeneity superficially good, especially for laser annealed membranes. The results of optical examinations of these membranes also showed that they having high permeability, especially in the regions of the visible spectrum and the near-infrared and increased  with increase the degree of oven annealing temperature and the duration of laser annealing, and less energy gap of these membranes values with increase the temperature degree of annealing or increase of laser annealing time, In addition the optical properties studied in this research included absorbance, reflectivity, refractive index, coefficients of absorption and extinction, and real and imaginary dielectric constants.