Investigations of CuInSe2 thin films and contact

This paper investigates the properties of CuInSeZ thin films grown on glass and on Mo substrates. The investigation is carried out with x-ray diffraction, RBS, XTEM, and SEM. CuInSeZ/Mo contact stability is investigated after annealing at 500 degrees C. RBS reveals that this treatment induces an interdiffusion between the metal and the chalcopyrite. To clarify this reaction, we have investigated the individual thin-film couples upon annealing. RBS and x-ray diffraction reveal insignificant interaction between Mo/Cu and Mo/In, but Se reacts with Mo. CuInSeZ (CIS) is one of the most promising materials for the growth of thin-film heterojunction solar cells. Efficiencies as high as 14% have been reported for CIS based solar cells. Such devices, however, require thin films with reproducible electrical and optical properties which are strongly influenced by the growth conditions and subsequent thermal treatments. The first part of this work is a characterization of the microstructure, the composition, the homogeneity, and the stability after annealing of CIS thin films deposited directly on glass or on a Mo-coated glass substrate. The second part of this work is an investigation of the interfacial reactions that take place with such CIS films when they are in contact with Mo. Information on that subject is limited. Published results seem to indicate a diffusion of CIS into Mo at elevated temperatures with possible formation of molybdenum selenides