ARSENIC INCORPORATION KINETICS IN GAAS(001) HOMOEPITAXY REVISITED

Reflection high-energy electron diffraction (RHEED) intensity oscillat ions have been used to obtain the arsenic incorporation coefficients f or 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 k inetic scheme which assumes that the incorporation process using eithe r As-2 or As-4 occurs via the formation of a molecularly adsorbed As-2 precursor. The variation of the incorporation coefficients with temp erature can be attributed to the fraction of As-2 which does not part icipate in the incorporation process as the temperature is increased. The final step leading to growth and the formation of GaAs depends onl y on the incorporation of arsenic from this intermediate, and the impl ication is that the final incorporation step is independent of the ars enic species used in growth. (C) 1997 Elsevier Science B.V.