Kinematical RHEED simulation of different structure models for the GaAs (311)A surface

We compare two different structure models proposed recently for the GaAs (311)A surface using kinematical calculations of their reflection high-energy electron diffraction (RHEED) patterns. Whereas for one structure the calculated pattern does not fit very well, the agreement between calculation and experimental pattern is excellent for the other and allows even structural refinement of the relaxation parameters. Consideration of only the topmost atoms of the surface in the calculation yields the best agreement with the RHEED pattern, which indicates a very small sampling depth of RHEED. Therefore, at least in special cases, the kinematical theory is a valid approximation to calculate RHEED patterns.