Microstructure and properties of the CdS thin films prepared by electrostatic spray assisted vapour deposition (ESAVD) method

Abstract

CdS thin films were fabricated using an electrostatic spray assisted vapour deposition (ESAVD) method from water/ethanol solutions of cadmium chloride and thiourea with different Cd:S ratios. The microstructure and crystallisation of the films were studied by means of XRD, XPS, AFM and SEM techniques. The effect of deposition conditions and precursor composition on the morphology and phase development of the films was investigated. Films with hexagonal phase and preferred [002] orientation were deposited at temperature below 400°C using a precursor solution with a Cd:S ratio of 1:3, whereas films deposited using a precursor solution with a Cd:S ratio of 1:1 showed no preferred orientation. The relationships between the microstructure of the films and their optical and electrical properties are discussed. The Cd:S ratio has very little influence on the optical property but has a tremendous effect on the conductivity of the CdS films. The results show that the ESAVD technique can produce CdS films with optical and electrical properties which may be suitable for solar cell applications.