Enhanced insight in the microstructure and composition of chalcopyrite type thin film solar cells

The performance of chalcopyrite type Cu In,Ga Se2 and CuInS2 thin film solar cells critically depends on microstructure of the thin films. Depending on the growth process, significant differences in the microstructure of films deposited by sequential or coevaportion processes are found. For the detailed analysis of the film microstructure and composition, cross section samples of various chalcopyrite type thin film solar cells were studied by means of electron backscatter diffraction EBSD and energy dispersive x ray spectrometry EDX in a scanning electron microscope SEM . The EBSD measurements on the cross sections allowed for precise determination of grain sizes, local orientations and also grain boundaries. The most frequent grain boundary types in chalcopyrite type thin films studied for the present work are amp; 931;3 twin boundaries. For as grown Cu S CuInS2 Mo glass stacks where the absorber is produced by rapid thermal processing using a sufficient amount of sulfur, it can be shown by means of EBSD and EDX that the Cu S on top of CuInS2 is not contiguous, and that the Cu S phase is hexagonal Cu