Effective doping concentration of indium on zinc oxide films using chemical spray pyrolysis technique

Abstract

Zinc oxide doped indium [ZnO:In] thin films have been deposited at (400±10)°C on glass substrates by chemical spray pyrolysis technique using zinc nitric (Zn(NO3)) and indium chloride (In Cl3) as a dopant precursor. The optical transmittance was less than 85% in the visible range for all films. The energy band gaps have been decreased with increased the indium concentrations which were (3.21eV) for pure zinc oxide, (3.23eV) for IZO 1% and (3.107eV) for IZO 3%. The X-ray measurement showed the ZnO films are formed with polycrystalline structure with hexagonal wurtzite type and five pronounced diffraction peaks, (100), (002), (101), (102) and (001). The crystalline size which measured from X-ray using Scherer equation decreased from 31nm to 12nm with increased indium doping concentration. The surface morphology investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface of the un-doped ZnO film and doped films were smooth and uniform.