Diffusion of Ga adatoms at the surface of GaAs(001) c(4x4) $\alpha$ and $\beta$ reconstructions

TL;DR

This study analyzes Ga adatom diffusion on GaAs(001) surfaces with c(4x4) reconstructions, revealing differences in diffusion speed and anisotropy between alpha and beta phases using energy landscape calculations.

Contribution

It introduces a variational approach to compute diffusion tensors based on known energy landscapes for Ga adatoms on different surface reconstructions.

Findings

Diffusion at the alpha surface is slower than at the beta surface.

Diffusion at the alpha surface is more anisotropic.

Activation energies for diffusion are calculated for both surface phases.

Abstract

Diffusion of Ga adatom at the As rich, low temperature c(4$\times$4) reconstructions of GaAs(001) surface is analyzed. We use known energy landscape for the motion of Ga adatom at two different $\alpha$ and $\beta$ surface phases to calculate diffusion tensor by means of the variational approach. Diffusion coefficient describes the character of low density adatom system motion at the surface. The resulting expressions allow to identify main paths of an adatom diffusion and to calculate an activation energy of this process. It is shown that diffusion at the $\alpha$ surface is slower and more anisotropic than this for the $\beta$ surface.