Investigation of optical properties of MgO thin films prepared by sol-gel method

MgO thin films were prepared using sol-gel method. The influence of annealing temperature on optical، structural properties and surface morphology of the films were investigated using FTIR، UV-Visible and photoluminescence (PL) spectroscopy، X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical constants and thickness of the films were determined by pointwise unconstrained minimization approach. The optical transmittance has decreased with increase of annealing temperature. The refractive index and extinction coefficient of the films increased while the thickness and optical band gap of the films decreased with increasing of annealing temperature. The thickness of film decreased from 635 to 420nm and optical band gap decreased from 4. 05 to 4. 02eV. The photoluminescence (PL) intensity increased with annealing temperature. XRD patterns demonstrated that the prepared films at 500℃ were amorphous. In addition، the crystal structure of MgO nanopowders which was prepared by sol-gel method was investigated. The crystalline orientation of MgO nanopowders was improved by increasing the sintering temperature. The SEM micrographs show that a homogenous and crack-free film can be prepared at 500°C.