Origin of electron diffraction oscillations during crystal growth

Measurements of the intensity oscillation phase of reflection high-energy electron diffraction during molecular beam epitaxy growth of GaAs and AlAs indicate that the oscillations are due to an interference effect within the surface reconstruction layer forming on the growing layer. The experimental results along a low-symmetry azimuth are explained by a basic theoretical model using only the layer thickness as a fitting parameter. Our conclusions are supported by energy loss measurements showing the absence of diffuse inelastic contributions with a different phase.