Macrostep formation and growth condition dependence in MBE of GaAs on GaAs (1 1 1)B vicinal surface

摘要

As/Ga ratio, off-angle, growth temeprature and growth time dendence of step bunching of GaAs (1 1 1) B surface inclined toward <1 1 0> was studied useing microprobe-RHEED/SEM MBE system and AFM. Step bunching occurs and macrosteps are created at low As/Ga ratio while at high As/Ga ratio they are decomposed into steps of a few monolayers. The macrostep terraces and risers were identified respectivley as (1 1 1)B and (2 2 1). Terrace width of the acrosteps ws found to depend on off-angle while step height was dept constant. Bothu terrace width and step height were independent of grwoth temeprautre in the temperature region in which the surface recosntruction of (1 1 1)B was 19×19. It was found that terrace width increase linearly with grwoth time and shows saturation when step height of the macrostep becomes 2 nm.