CU/IN DEPOSITED AT ROOM-TEMPERATURE - MORPHOLOGY, PHASES AND REACTIONS

Bilayers of a slightly copper-rich composition of copper and indium deposited (in that order) at room temperature by vacuum evaporation, electroplating, and r.f sputtering, were analyzed by MeV He-4 backscattering spectrometry, scanning electron microscopy and X-ray diffraction before and after thermal annealing at 400-degrees-C in vacuum. The surface morphology of as-deposited samples is roughest for evaporated samples and smoothest for samples deposited by sputtering with low r.f. power. All as-deposited samples contain copper and indium phases and the metastable Culn compound. After 1 h at 400-degrees-C, this metastable phase and that of copper disappear and are replaced by some copper-rich compound (Cu9In4, Cu7In4) in all cases. Simultaneously, the surface morphology smooths out considerably for the initially rough samples. Bilayers of various Cu/In compositions were also prepared. The results are consistent with the absence of stable compounds outside the 26-38 at.% indium range, as indicated by published phase diagrams.