Metastability of CuInS2 and its implications on thin-film growth

Thin layers of the ternary chalcopyrite semiconductor CuInS2 grown epitaxially on Si(001) substrates were investigated with respect to the existing phases and their lattice parameters by means of x-ray diffraction at the European Synchrotron Radiation Facility in Grenoble (France). The predominant parts of the samples exhibit the metastable CuAu-type ordering. The smaller volume fractions of the samples showing the ground-state chalcopyrite ordering are distorted in order to accommodate themselves to the tetragonal CuAu-type structure. It is suggested that this finding is a consequence of the growth mode of CuInS2 thin films.