Optical and electronic properties of zinc oxide films prepared by spray pyrolysis

Abstract

The optical properties of transparent conducting zinc oxide (ZnO) films prepared by spray pyrolysis were studied in the UV, visible and IR regions. The specular reflectance and transmittance data were used to determine the optical constants which correlate well with the data on single-crystal ZnO in the visible region. The optical behaviour in the IR region was explained on the basis of the Drude model. The electronic properties are found to be thickness dependent. The films doped with 3 at.% In exhibit thermal stability up to 650 K in vacuum and up to 450 K in oxygen ambients. The changes in the electrical properties of pure ZnO films on annealing in oxygen and vacuum are attributed to chemisorption and desorption of oxygen at grain boundaries.