MONOLAYER-RESOLVED X-RAY-EXCITED AUGER-ELECTRON DIFFRACTION FROM SINGLE-PLANE EMISSION IN GAAS

Using GaAs/AlAs/GaAs heterostructures we report measurements of complete hemispheric Auger-electron diffraction patterns originating from single well-defined subsurface sites within a crystal lattice. With this data set a detailed experimental analysis of multiple elastic-scattering effects is performed. We investigate the dependence of the forward enhancement factor along atomic chains on the length and on the internal structure of the chain. No randomization of the elastically scattered electrons is observed even for long traveling path lengths. The angle-dependent features related to elastic scattering as well as those originating from inelastic scattering are evaluated independently to obtain depth profiles of the electron-emitting atoms. Both types of depth profiles indicate a microscopic redistribution of Al and Ga in a surface region of one bilayer thickness.