Characteristics of ZnO and Al Doped ZnO Thin Films Prepared by Sol Gel Method for Solar Cell Applications

Abstract

Pure and Al-doped ZnO (AZO) thin films with different aluminium (Al) concentrations (Al: 0.5, 1, 2, and 3 wt.%) were prepared on p-type Si(100) substrate by a dip-coating technique using different zinc and aluminum precursors. The structural, morphological, optical and electrical properties of these films were investigated using a number of techniques, including the X-Ray Diffraction (XRD), scanning electron microscopy (SEM), Atomic force electron microscopy (AFM), ultraviolet–visible spectrophotometry, photoluminescence(PL) spectroscopy and four-point probe technique. The X-ray diffraction (XRD) results shown that the obtained (AZO) films were polycrystalline with a highly c-axis preferred (002) orientation, and the average crystallites size decrease from 28.32 to 24.61 nm with the increase in Al dopant concentration. The studies demonstrated that the ZnO film had a good transparency in the visible range with the maximum transmittance of 95% and the band gaps (Eg) varied from 3.16 to 3.26 eV by alumium doping. Scanning electron microscopy (SEM) images showed that the surface morphology of the films changed with increase of Al-doping. The photoluminescence spectra also showed changed with Al-doping.