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 4He backscattering spectrometry, scanning electron microscopy and X-ray diffraction before and after thermal annealing at 400 °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 CuIn compound. After 1 h at 400 °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.
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