The reflection high-energy electron diffraction (RHEED) specular spot intensity oscillations that were obtained during low-temperature regime and surfactant mediated regime of molecular beam epitaxial (MBE) growth of GaAs is studied and explained using modified stochastic model and a rate equation model, respectively; The dynamics of the physisorbed As layer were introduced into the stochastic model by including the thermally activated processes of chemisorption into and evaporation out of the As physisorbed state. Increased scattering of the RHEED beam due to the higher physisorbed As coverage at 2:1 leads to a factor of 5 decrease in the steady-state amplitude of the RHEED oscillations compared to the 1:1 case. These results are in excellent agreement with the experimental results. A factor in maintaining this growth mode is that arsenic stays in the physisorbed state with lifetimes in the range of 10{dollar}\sp{-3}{dollar} to 10{dollar}\sp{-5}{dollar} seconds and incorporates only when an appropriate configuration of Ga atoms forms on the surface; Beating in the reflection high energy electron diffraction (RHEED) intensity oscillations were observed during molecular beam epitaxial (MBE) growth of GaAs with Sn as a surfactant. A rate equation model of growth was developed to explain this phenomenon by assuming that the GaAs covered by the Sn grows at a faster rate compared to the GaAs not covered by Sn. Assuming that the electron beams reflected from the Sn covered surface and the rest of the surface are incoherent, the results of the dependence of the RHEED oscillations on Sn submonolayer coverages for various Sn coverages were obtained and compared with experimental data and the qualitative agreement is very good. (Abstract shortened by UMI.)
