Experimental studies of surface resonance scattering processes in rheed

Abstract

A high energy electron diffraction experimental has been carried out in which both the reflection high energy electron diffraction pattern (RHEED) and transmission high energy electron diffraction pattern (THEED) are recorded together from the edge of a GaAs bulk crystal specimen. The combined diffraction pattern shows clearly the existence of the surface resonance waves when the surface resonance diffraction conditions are satisfied, and the close correlation between the intensity enhancement and the surface resonance waves. Strong intensity dependence of the specular reflection and surface resonance spot on the positions of the specular reflection spot along the Kikuchi envelopes, and experimental identification of the surface resonace region, demonstrates the relationship of the resonance diffraction processes to the three-dimensional diffraction conditions. However, the fact that the wavefield for the surface-channelled electrons is confined to a few atomic layers on the surface is indicated by the elongatition of the transmitted diffraction spots. Generation of diffusely scattered electrons by the surface-channelled electrons produces diffuse bands in the diffraction pattern, parallel to the surface.