Chemical bath deposition of indium hydroxy sulphide thin films: process and XPS characterization

Indium hydroxy sulphide thin films have been deposited from an acidic bath using indium (III) chloride, thioacetamide and acetic acid as complexing ag ent. It has been found that the proper control of deposition conditions sig nificantly influences the film quality and reproducibility as well as the f ilm thickness. XPS measurements have been carried out for samples prepared using different reactant concentrations in order to study variations in the surface composition. Some films have been also air-annealed at 300 and 400 degrees C to know in which way the composition is affected by this process ing. Films are formed by indium hydroxy sulphide, indium oxide and indium s ulphate having contaminant species adsorbed on the surface. All samples ann ealed have shown an oxygen incorporation from the air and an important sulp hur loss. The S/In atomic ratio in the indium hydroxy sulphide compound is about one for the non-annealed samples showing that the compound is sulphur deficient. When samples are annealed at 400 degrees C, this value is decre ased down to 0.3 owing to the formation of sulphur containing volatile spec ies. The molecular formula for the indium hydroxy sulphide as deposited can be close to InOHS with slight variation in the OH:S proportion depending o n the deposition conditions and the annealing temperature. (C) 1999 Elsevie r Science S.A. All rights reserved.