The surface evolution and kinetic roughening during homoepitaxy of GaAs (001)

Abstract

Scanning tunneling microscopy studies have been performed on GaAs homoepitaxial films grown by molecular-beam epitaxy. Images show that in the earliest stages of deposition the morphology oscillates between one with two-dimensional islands and flat terraces. After the initial transient regime, the system evolves to a dynamical steady state. This state is characterized by a constant step density and as such the grown mode can be termed step flow. Comparison with reflection high-energy electron-diffraction (RHEED) shows that there is a direct correspondence between the surface step density and the RHEED specular intensity. Thick films (up to 1450 monolayers) display a slowly-increasing surface roughness. Analysis of the scaling properties and comparison with theories of film growth will be made.