Synthesis of In₂S_3(1-x)O_3xthin films by oxidation of In₂S₃film and influence of film microstructure

Abstract

In2S3(1–x)O3x is known from preceding studies to have a bandgap varying continuously as a function of x, which is 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 microstructure 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 energy dispersive X‐ray spectroscopy (EDX)) were used to get information on the compounds and the microstructure of films. The main conclusion of the paper opens the perspective of practical applications for producing layers for solar cells.

Study of the Oxidation Process of Crystalline Powder of In2S3 and Thin Films Obtained by Dr Blade Method

“…m0 is the mass reached asymptotically at a given temperature, determining the composition. In this expression  , A, and m0 are indeed determined to be dependent on the annealing temperature in air atmosphere; is determined to vary from 8.3 min at 476 C to 2.2 min at 746 C. These values are comparable to those determined in the nanometric power but at much lower temperatures [21]. The upper curve represents the mass loss versus time obtained on heating first in N2 atmosphere, and then at high temperature (800 C in the present case) when changing the atmosphere to air.…”

“…This situation motivated us to investigate the possibility to obtain In2S3 films by Dr Blade technique, and to study their oxidation. We thus carefully studied the behaviour of such films and constitutive crystalline powders, that have grains with a micrometric size as evidenced in the SEM, to be compared with results obtained with nanometric powders resulting from thin films as studied in [21].…”