Surface Structure Analysis Using Reflection High-Energy Electron Diffraction

For the reconstructions present during epitaxial growth, the diffraction experiment of choice is reflection high-energy electron diffraction (RHEED). In the RHEED geometry, the momentum transfer normal to the surface is small and can be varied by changing the angle of incidence at constant incident energy. The resulting rocking curve, or diffracted intensity versus angle of incidence, is comparable to a low-energy electron diffraction IV profile. We present rocking curve results for the 〈001〉 and 〈11̄0〉 principle azimuths for 10-keV diffraction experiments from GaAs(110). This known surface structure is the best tested structure to develop the analysis. The measurements are compared to a fully convergent dynamical N-beam RHEED calculation which includes as many propagating and evanescent beams as needed. An important issue is to determine what extent the diffraction is dominated by bulk features and single-layer resonances. This is addressed by selectively eliminating beams in the analysis and comparing beam emergence predictions to experimental observations.