Morphological, electrical and optical properties of zinc oxide films grown on different substrates by spray pyrolysis technique

Zinc Oxide thin films of thickness 0.7 mu m has been prepared by spray pyrolysis technique on to the sapphire and glass substrates kept at 500 degrees C. The films were formed using two different molar concentration ie 0.15 and 0.2M. These films were characterized for SEM and XRD analysis and it was observed that the average size of the crystallites were of order of 400nm and 325nm for sapphire and glass respectively. XRD analysis revealed that the intensity of peaks were more pronounced in sapphire as compared to glass. Moreover the intensity of (002) plane were increased in both the samples (films on sapphire and glass) as the concentration of spray solution was increased. V-I characteristics were analyzed for both the samples (using two probe method) and was observed that resistivity for glass and sapphire were of order of 140ohm-cm and 110ohm -cm respectively. Moreover the films were annealed at temperature 350 degrees C for 2hours in vacuum (10(-5) torr) and was found that resistivity for films on sapphire were decreased by 10(1). Optical properties for both the samples were studied and was found that band gap for films grown on sapphire was more by 0.02eV as compared to the films on glass.