Arsenic incorporation kinetics in GaAs(001) homoepitaxy revisited

Reflection high-energy electron diffraction (RHEED) intensity oscillations have been used to obtain the arsenic incorporation coefficients for the homoepitaxial growth of GaAs on the (001) surface at different substrate temperatures. The incorporation coefficients of As-2 and As-4 are both temperature-dependent and saturate at maximum values of 1.0 and 0.5 at low temperatures. The results have been modelled using a kinetic scheme which assumes that the incorporation process using either As-2 or As-4 occurs via the formation of a molecularly adsorbed As-2* precursor. The variation of the incorporation coefficients with temperature can be attributed to the fraction of As-2* which does not participate in the incorporation process as the temperature is increased. The final step leading to growth and the formation of GaAs depends only on the incorporation of arsenic from this intermediate, and the implication is that the final incorporation step is independent of the arsenic species used in growth. (C) 1997 Elsevier Science B.V.