Two phases in the initial stages of Cu growth on Ge(111) have been investigated by using X-ray photoelectron diffraction (XPED). Multiple-scattering analysis showed that the surface layer of the discommensurate phase consists of almost the same amount of two kinds of domains with regular and fault stackings. Furthermore, it was found that the ordered overlayer was formed after annealing the discommensurate phase and that the XPED pattern from the annealed phase cannot be explained by the simple models such as bulklike Cu and stoichiometric germanide Cu 3 Ge .
