Kinetically driven self-organization during hydrogen-assisted MBE growth on GaAs( 110)

摘要

Self-organized growth of GaAs on (110) substrates vicinal to (111)A by hydrogen-assisted molecular beam epitaxy (H-MBE) has been studied for different kinetic regimes using atomic force microscopy (AFM). When GaAs growth is limited by kinetics of adatom incorporation to steps, the presence of chemisorbed H on the surface after oxide removal promotes the incorporation of adatoms to steps from the lower terraces, leading to the formation of laterally ordered multiatomic step arrays by step bunching in the Ga-supply limited regime and ridge patterns in the As-limited regime with improved uniformity and reduced dimensions with respect to those formed by conventional MBE growth. We attribute these changes in pattern morphology to a rapid self-organization of the surface associated with a reduction of the Ehrlich-Schwoebel (E-S) barrrier to As from the lower terraces being incorporated at steps via dissociation of an AsH_2~* intermediate.