Formation of Flat Monolayer-Step-Free (110) GaAs Surfaces by Growth Interruption Annealing during Cleaved-Edge Epitaxial Overgrowth

Abstract
We have characterized, by means of atomic force microscopy, the as-grown and subsequently in situ annealed surfaces of 5 nm GaAs layers grown by molecular beam epitaxy (MBE) on a vacuum-cleaved (110) GaAs surface, and find that a high temperature growth interruption and anneal remarkably improves the surface morphology of the (110) GaAs layer. Interruption of the 490°C epitaxial GaAs growth by a 10 minute anneal at 600°C under an As4 overpressure produces an atomically-flat surface free of monolayer step edges over areas measuring several tens of µm on a side. These results suggest that the (110) GaAs surface has much higher stability under annealing conditions than under MBE growth conditions.