Molecular beam epitaxy/atomic layer epitaxy growth processes of wide-band-gap II–VI compounds: Characterization of surface stoichiometry by reflection high-energy electron diffraction

Abstract

A good agreement is found between the observed temporal dependence of the reflection high-energy electron diffraction (RHEED) intensity variation of a specular spot and the calculated temporal dependence of surface coverage during sublimation and adsorption processes in atomic layer epitaxy. Here the surface coverage is calculated on the basis of a phenomenological model in which precursor states are taken into account. The RHEED oscillation behavior during molecular beam epitaxy (MBE) growth of Zn chalcogenides is investigated for various growth conditions. The RHEED intensity saturates at a certain level and the saturation level is closely correlated with the surface stoichiometry or the surface coverage. It is concluded that the RHEED intensity variation corresponds to the change in surface coverage during ALE and MBE growth. It is possible to characterize the surface stoichiometry during atomic layer epitaxy (ALE) and MBE growth by RHEED.