Thermal Decomposition of Ternary Chalcopyrite Thin Films

Polycrystalline thin films of the ternary chalcopyrite semiconductors CuIn 3 Se 5 and CuInSe 2 , prepared by a coevaporation process, have been investigated with the Temperature Programmed Desorption method (TPD). The desorbing species have been detected with a mass spectrometer for temperatures up to 750°C. Morphological changes have been observed with SEM and compositional data have been recorded before and after the heat treatments. The decomposition process has been found to start at about 500°C with outgasing of Se 2 species, followed by the desorption of In 2 Se starting at 600°C. CuIn 3 Se 5 thin films could be transformed totally to Cu 2 Se.