Atomic-scale Monte Carlo study of step-flow growth modes onGaAs(001)−(2×4)

Abstract

The step-flow growth modes of the $\mathrm{GaAs}(001)\ensuremath{-}\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ structure growing by molecular-beam homoepitaxy are studied by the Monte Carlo simulation method using a two-species kinetic growth model. Our results show that a terrace edge parallel to the $[1\ifmmode\bar\else\textasciimacron\fi{}10]$ direction does not grow in a coherent manner but by the growth of rather short segments of As dimer rows. For terrace edges perpendicular to this direction, we find that the growth morphology depends strongly on the relative phase of the $(2\ifmmode\times\else\texttimes\fi{}4)$ structure between an upper terrace and a lower one. More precisely, when they are out of phase with each other in the $[110]$ direction, growth proceeds principally by kink propagation in this direction, whereas, if they are in phase with each other, an As dimer row grows on top of the As dimer rows of the lower terrace, followed by growth in the directions perpendicular to it, resulting in the creation of a peninsula.