Growth Kinetics of Copper Sulfide Thin Films by Chemical Bath Deposition

Abstract

Copper sulfides (CuxS) are compound semiconductor materials that exhibit considerable variations of optical and electrical properties. Copper sulfide thin films can be used in many applications, such as solar control coatings, solar cells, photothermal conversion of solar energy, electroconductive coatings, and microwave shielding coatings. In this paper, chemical bath deposition growth of copper sulfide thin films were monitored for the first time using an in-situ quartz crystal microbalance as a function of time, temperature, concentrations of reactants, and pH. The reaction activation energy was determined based on initial growth rates. The high activation energy, 68 [kJ/mol], indicates that the rate limiting step of the deposition is the chemical reaction rather than mass transport. The structure, morphology, composition and optical absorption of the films were studied by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and UV-Vis absorption spectroscopy respectively. These properties were found to depend strongly on the deposition conditions.