LIMITING MECHANISM OF MOLECULAR-BEAM EPITAXIAL-GROWTH OF ALGAAS ON (111) FACE

AlGaAs layers have been grown on GaAs(100) and 0.5-degrees-misoriented GaAs(111)B substrates by molecular beam epitaxy using As4 and As2. The quality of (111)B-oriented AlGaAs becomes poorer when more As-stabilized growth conditions are employed; such as higher As pressure, lower substrate temperature and the use of As2 instead of As4. We propose a model where the As-trimer structure of As-stabilized (111)B surface with the (2 x 2) reconstruction disturbs the incorporation of group III adatoms into lattice sites. In order to confirm this model, we have grown GaAs layers with thin AlAs marking layers over mesa-shaped GaAs(100) substrates with (111)B and (111)A side walls, and observed that the growth rate of GaAs on the (111)B face is very much reduced by using As2 as compared with the growth using As4. This indicates the difficulty of Ga incorporation into the (111)B face, which is not the case for the (111)A face.