Sol gel dip coated Aluminium doped zinc oxide films and their properties

Abstract

ZnO films were deposited on cleaned glass substrates from AR grade zinc chloride, acrylamide, bisacrylamide and ammonium persulphate. X-ray diffraction studies indicated the major diffraction peaks decreased with increasing the Al concentration. For doping with aluminium, 0.01M of AICI3 was introduced in the deposition mixture. The band gap varies from 3.16 eV to 3.20 eV with increase of Al doping. This blue shift behavior or broadening in the band gap is mainly due to the Moss-Burstein band filling effect. The grain size and surface roughness varied from 45 nm to 15 nm and 3.5 nm to 1.3 nm respectively with increase of aluminium concentration. The electrical resistivity of the films decreases with increase of Al doping by three orders of magnitude. The mobility and carrier density increase with Al doping. Comparing the Al doped ZO with the undoped ZnO films, Al(TO) and El (LO)modes are shifted to the high frequency side in the Raman spectrum.