Effect of Aluminium Doping on Structural and Optical Properties of ZnO Thin Films by Sol-Gel Method

We systematically investigated the structural, morphological and optical properties of 0.05 mol % Al doped ZnO (Al: ZnO) thin films deposited on glass substrates by sol-gel spin coating method. The influences of Al doping in ZnO thin films are characterized by Powder X-ray diffraction study. ZnO and Al: ZnO thin films have showed hexagonal wurtzite structure without any secondary phase in c-axis (002) orientation. The SEM images also proved the hexagonal rod like morphologies for both films. All the films exhibited transmittance of 70-80% in the visible range up to 800 nm and cut-off wavelength observed at similar to 390 nm corresponding to the fundamental absorption of ZnO. The band gap of the ZnO thin films slightly widened with the Al doping. The photoluminescence properties have been studied for Al: ZnO thin films and the results are presented in detail.