ABSTRACTWe report a study of the microstructure and surface morphology of co-deposited Al-Ge films. At 200 °C and above, the terminal solid solutions are obtained, whereas at lower temperatures, metastable amorphous or crystalline phases coexist with the Al-rich terminal phase. For film thickness below 200 nm, lateral phase separation is observed with surface grooving which reflects the bulk microstructure. Analysis of the data with a model for the diffusion process shows that the results are consistent with a surface diffusion mechanism. For thicker films, there is a transition into a layered microstructure in which Al segregates to the surface. This transition is explained in terms of the surface and interfacial energies of the phases.
