Effect of heat treatments in vacuum on CdS thin films prepared by the spray deposition technique

Abstract

The effects of short heat treatments in vacuum (10 min at 200–400°C) on the electrical, structural and optical properties of hexagonal polycrystalline CdS thin films prepared by the spray deposition technique were studied. It was found that the electrical and structural properties change remarkably under these treatments. However, the optical properties do not vary significantly. The resistivity, in particular, decreased from about 500 Ω cm to less than 1 Ω cm for a 300°C annealing while the electron mobility increased by two orders of magnitude, a result similar to that reported by Martinuzzi and coworkers. A hexagonal phase was obtained regardless of deposition temperature. The preferential orientation changed when samples were subjected to vacuum annealing at 300°C or more, indicating that a recrystallization had taken place in the films.