RHEED OSCILLATIONS AT SPECIAL DIFFRACTION CONDITIONS

It is suggested that analysis of RHEED intensity oscillations can be simplified when diffraction conditions are chosen appropriately and two cases are presented as supporting evidence. The first is an out-of-phase condition where the specular reflection from the substrate is very weak. At this condition the oscillations can be described by a kinematic calculation which is modified to take account of refraction. The second case occurs when electrons are incident at glancing angles less than about 1-degrees. Under this condition the oscillations can have a double-minimum structure with one minimum at very small coverages of the growing layer and a second minimum at higher coverages. The minima occur because the growing layer becomes near-transparent at certain critical strengths of the laterally averaged scattering potential. This is illustrated with numerical results for lead and silver.