THE SURFACE EVOLUTION AND KINETIC ROUGHENING DURING HOMOEPITAXY OF GAAS (001)

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