PREPARATION AND STUDY OF CUXY2 (X=GA, IN Y=SE, TE) THIN-FILMS FOR SOLAR-CELL APPLICATIONS

This paper concerns the study of thin films Of CuXY2 (X = Ga, In ; Y = Se, Te) photovoltaic materials. The thin films were grown from a close-spaced vapour transport technique in closed tube, with iodine as reagent. After a review of the method and the published results concerning the thermodynamical aspect, we give some results of characterization of the thin films grown with this method. The conditions of quasi-stoichiometric deposition were determined. Phase transitions were observed : for example, for CuInSe2 and at source temperatures above 580-degrees-C, the films are formed of (In, Se) compounds, mainly In2Se3 and InSe. These films have a n-type conductivity, while the CuInSe2 films, Obtained at T < 580-degrees-C, have a p-type conductivity. Hence, either p-type or n-type films can be grown, simply by varying the source temperature. These results were complemented by a study of the films grown by close-spaced sublimation (CSS) at moderate temperature, using the same apparatus. The films are also formed of (In, Se) compounds.