DOUBLE PERIOD RHEED OSCILLATIONS DURING MBE GROWTH OF GAAS AND ALAS ON THE GAAS(110) SURFACE

Molecular beam epitaxy (MBE) of GaAs and AlAs on the GaAs(110) surface has been studied in situ using reflection high-energy electron diffra ction (RHEED). Additionally ex situ atomic force microscopy (AFM) has been employed to investigate the surface topography after the growth. During the growth complex RHEED oscillations with a single and a doubl e period can be measured, depending on the diffraction feature that is monitored. The AFM images of the surface reveal mono- and bilayer hig h steps and islands, reflecting a layer-by-layer growth with the parti cipation of both at the same time. A simple model that leads to a qual itative understanding of the experimental observation is presented.