Characterization of Undoped/doped Zinc Oxide Films by Sol Gel Method on Different Substrates

Abstract

Aluminum doped Zinc Oxide films were prepared by Sol Gel dip coating method on Sapphire and Mica substrates. Zinc acetate solution of 0.2 and 0.4M in isopropanol stabilized by diethanolamine and doped with a concentrated solution of aluminum nitrate in ethanol were used. The content of aluminum in the sol was 2 at.%. The dipping of substrates were repeated up to 15 to 20 times to have thickness of films of range 0.5-0.8µm. XRD analysis of films grown on both Sapphire and Mica revealed that grains of undoped and doped films grew preferentially along the (002) plane but intensity of (002) was found to be more for mica than that of film grown on Sapphire. Average size of Crystallites using SEM measurements were found to be 50nm and 95 nm for the films grown on Sapphire and mica. The electrical resistivity were measured by a four-point probe method and it was revealed that electrical resistivity of the films grown on mica were lower than that on Sapphire but after annealing of the films for 1 hour (in vacuum) at 350°C the films on Sapphire substrate showed decrease in resistivity but no major changes in resistivity were observed on films grown on mica. Moreover optical band gap studies of films on both substrates were carried out.