Multi-Atomic Steps on Metalorganic Chemical Vapor Deposition-Grown GaAs Vicinal Surfaces Studied by Atomic Force Microscopy

We studied MOCVD-grown GaAs (001) vicinal surfaces by atomic force microscopy (AFM) and observed multi-atomic steps (multisteps) of several-monolayers height. The multisteps become straight as the AsH3 partial pressure increases and when the misorientation direction is [1̄10]. As growth proceeds, first, multisteps, i.e., step bunches, form and then the average distance between multisteps saturates. The multistep straightening and the multistep formation mechanisms are discussed.