Relevance of surface reconstruction to specular RHEED intensity on GaAs(001)

Abstract

By carrying out atomic-scale growth simulations of a $\mathrm{GaAs}(001)\ensuremath{-}\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ surface, we find that the density of double As dimers evolves synchronously with the observed specular reflection high-energy electron-diffraction (RHEED) intensities in growth and after its interruption. At the same time, we find that a step density does not even oscillate during growth. We further show that the structural transition of initial growing islands from a non-(2\ifmmode\times\else\texttimes\fi{}4) structure to the $\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ structure found previously can be detected in situ by specular RHEED observation. The fast and slow recovery processes after growth interruption are identified, respectively, as the incorporation of Ga adatoms to surface structures, and the phase ordering of various domains consisting of the $\ensuremath{\beta}2(2\ifmmode\times\else\texttimes\fi{}4)$ structure. We also relate these results to a specular RHEED intensity with the help of ab initio calculations.