Molecular Beam Epitaxial Growth Mode Transitions on Vicinal Surfaces

Abstract

ABSTRACTKinetic model of MBE growth on vicinal surface is investigated. The model includes step propagation, nucleation and growth of islands on the terraces and Schwoebel barrier at descending step edges as -well. By numerical solution of kinetic rate equations for growth on stepped surface, adatom and island density profiles across a terrace are obtained. With using simple criterion for growth mode transition the "phase diagram" of growth modes in parametric space γ–β is constructed, γ∼J/D and β∼tan-2φ, where J is the atomic flux, D is the surface diffusion coefficient and φ is the substrate miscut angle. The transition curve in the γ–β plane separating step flow mode region from the mixed (step-flow+nucleation) growth mode region is well describded by a simple equation γ=A/β3 where constant A=10 and 100 with and without Schwoebel effect. The relations for critical terrace width (miscut angle) and transition temperature are derived and it is shown that these relations are in fairly well agreement with available experimental data on the MBE growth of GaAs.