Oxidation of In2S3 films to synthetize In2S3(1-x)O3x thin films as a buffer layer in solar cells

In2S3(1-x)O3x is known from preceding studies to have a bandgap varying continuously as a function of x, the reason why this solid solution is potentially interesting in the field of photovoltaics. In this work, we present results on oxidation of In2S3 by heating in air atmosphere to obtain the desired material. The oxidation is accompanied by a mass loss due to the substitution of S by O atoms that is studied by means of thermogravimetric analysis. It appears that the temperature region in which the oxidation occurs is strongly dependent on the texture of deposited films. As-grown films deposited by chemical bath deposition are subjected to nano-oxidation occurring at lower temperature than oxidation of materials that are characterized by a better crystallinity and larger crystallite size. X ray diffraction and scanning electron microscopy (including EDX) were used to get information on the compounds and the texture of films. The main conclusion of the paper opens the perspective of practical applications for producing layers for solar cells.