Synergetic effects of aluminium and indium dopants in the physical properties of ZnO thin films via spray pyrolysis

We report a comparative study of various physical properties of Aluminium and Indium co-doped Zinc Oxide (AIZO) thin films with singly doped films, namely Aluminium doped ZnO (AZO) and Indium doped ZnO (IZO) thin films. Thin films were deposited by Spray Pyrolysis technique at a substrate temperature 425 degrees C and the concentration of the dopants Aluminium (Al) and Indium (In) were varied from 0.5 to 2 at.% in an equimolar manner for co doping. The properties of the co doped films (AIZO) are compared with AZO 3 and IZO 3 thin films. The physical properties such as crystallinity, morphology, topography, luminescence, optical and electrical properties of the ZnO films with respect to the dopant concentrations are investigated. The (101) peak of ZnO was found to become prominent with increasing doping concentrations. At lower doping concentrations, the morphology was seen to be flower-like, whereas pyramidal grains were observed for highly doped films. The AIZO 1.5 film was seen to be highly transparent in the visible region and it showed an electrical resistivity of rho = 3:56 x 10(-2) Omega cm. The transmittance of films was found to increase with doping percentages and was comparable to that of AZO 3 and IZO 3 at high doping. The properties of the co-doped films were seen to be more AZO 3 - like at lower doping concentrations and it tends to be more like IZO 3 at higher doping percentages.