Developing cadmium-free window layers for solar cell applications: some factors controlling the growth and morphology of β-indium sulfide thin films and related (In,Zn)S ternaries

Abstract

Suitable conditions for reproducible deposition of good quality In₂S₃ thin films on tin oxide coated (TO) glass substrates by low temperature solution deposition have been identified. Baths containing various carboxylic acids yield adherent, specular and crystalline films but with discernible morphological differences, within a defined pH range. Films have been characterised by XRD, SEM, XPS and electronic spectroscopy. The as-deposited films were found to be tetragonal β-In₂S₃; no evidence for the incorporation of hydroxy-indium species was detected by XPS measurements. The formation of ternary (In,Zn)S material, structurally similar to β-In₂S₃, appears to be possible via incorporation of zinc salts in similar deposition baths.