An x-ray-diffraction experiment performed on a germanium (111) crystal shows both rodlike and diffuselike scattering from the surface on a nonspecular crystal truncation rod. These scattering contributions are explained using existing theory on surface roughness. Two treatments to the Ge(111) surface have been used to provide examples with different roughness characteristics for this study. The magnitude of the roughness and the lateral scale of surface flat regions are obtained for both cases.

• Received 11 April 1989

DOI:https://doi.org/10.1103/PhysRevB.40.3480