A room-temperature-deposited (Formula presented) film on a Ge(100)-(2×1) surface retains the clean-surface (2×1) dimers at the interface. This is revealed by Patterson analysis of synchrotron x-ray-diffraction measurements of numerous in-plane fractional-order diffraction spots. The result suggests a mild interaction between the room-temperature-deposited film and the substrate surface reconstruction. The (Formula presented) film shows a (111) growth direction, and its (Formula presented) azimuth is oriented parallel to the (062)\ directions of the substrate. The result is a domain structure consistent with the threefold symmetry of the (111) growth direction and the two-domain, twofold symmetry of the substrate surface. © 1998 The American Physical Society.