Surface smoothness and step bunching on GaAs (111)B facets formed by molecular beam epitaxy

GaAs trapezoidal structures grown by molecular beam epitaxy on mesa-patterned (001) substrates have been studied by atomic force microscopy to clarify the morphology of (111)B facet planes. It is found that multi-atomic steps of 1-4 nm in height Delta appear on the facets with typical periods Lambda of 30-60 nm. When the mis-orientation angle Delta theta of mesa-stripes with respect to [110] increases from 2 degrees to 7 degrees, the corrugation height Delta is found to increase monotonically. Thus the mis-orientation angle Delta theta must be minimized to form smooth facet structures.