Effects of solution concentration on the structural and optical properties of CuAlO2 thin films prepared on 4H-SiC via sol-gel method

Abstract

In this work, the effects of solution concentration on the crystal structure, optical properties and surface morphology of the CuAlO2 thin films prepared on 4H-SiC (0001) by sol-gel method were studied. X-ray diffraction (XRD) indicates that the CuAlO2 films are polycrystalline and have a high preferential growth orientation (012). In addition, four emission peaks were observed from room temperature photoluminescence (PL) spectra. The emission peaks at 360 nm (3.45 eV) and 380 nm (3.26eV) are near band edge emission of CuAlO2 film and 4H-SiC substrate, respectively. The other two emission peaks at 410 nm (3.02 eV) and 470 nm (2.64 eV) arises from Cu-vacancy defect. The surface roughness of the films was increased in the case of high solution concentrations, resulting a reduction in the optical transmittance. However, an overall improvement in crystallinity of the films and reduction of Cu-vacancy defect was observed with the increased solution concentrations.