Oscillation of the mirror and fractional RHEED reflections during homoepitaxy on the (2×4)-reconstructed GaAs(001) surface

Oscillations of the intensity of mirror and fractional RHEED reflections during homoepitaxy on the GaAs(001)-(2×4) reconstructed surface were studied. A considerable difference was observed in the patterns of intensity variation for the mirror and the fractional (0 1/4) and (0 3/4) reflections corresponding to the α and β phases on the reconstructed surface. A kinetic scheme of elementary processes occurring on the Ga(001) surface upon the homoepitaxial growth initiation is proposed. The activation energy for the nucleation process was experimentally determined (5-eV). It is shown that the temperature dependence of the probability of critical nucleus formation is determined by the desorption of As₂ dimers.