Low-temperature molecular beam epitaxy of gallium arsenide Antisite incorporation and Rheed oscillations: A theoretical study

Surface dynamics dominate the incorporation of charged and neutral antisite arsenic and the temporal variation of reflection high energy electron diffraction (RHEED) intensity in the low temperature (LT) molecular beam epitaxy (MBE) of (100) gallium arsenide (GaAs). A comprehensive rate equation model is proposed based on the presence and dynamics of a physisorbed arsenic (PA) riding the growth surface which dictates the incorporation and concentration of antisites and the RHEED oscillations (ROs) behavior. The dependence of antisite concentrations on growth parameters can be explained based on the saturation of the PA layer coverage at a monolayer and the competing rate processes such as the incorporation into and evaporation of antisite arsenic from the crystalline surface. The RHEED intensity is computed based on kinematical theory of electron diffraction with different interplanar distances for the PA layer (2.48A) and the crystal (1.41A). At temperatures and beam equivalent pressures (BEP)s when the surface coverage is 0.5, the resulting RHEED reflection contributions from both surfaces covered by the PA layer and the crystal interfere destructively to result in no ROs