Fast atom diffraction inside a molecular beam epitaxy chamber, a rich combination

TL;DR

This paper reviews how grazing incidence fast atom diffraction (GIFAD) can precisely characterize surface structures and monitor surface roughness during molecular beam epitaxy, combining experimental results and theoretical analysis for GaAs surfaces.

Contribution

It demonstrates the effectiveness of GIFAD in in-situ surface analysis and growth monitoring during MBE, with new experimental and theoretical insights into surface structural characteristics.

Findings

GIFAD provides in-situ atomic-scale surface topology information.

GIFAD can track changes in surface roughness during layer growth.

The technique reveals structural details of GaAs surfaces during MBE.

Abstract

Two aspects of the contribution of grazing incidence fast atom diffraction (GIFAD) to molecular beam epitaxy (MBE) are reviewed here: the ability of GIFAD to provide \emph{in-situ} a precise description of the atomic-scale surface topology, and its ability to follow larger-scale changes in surface roughness during layer-by-layer growth. Recent experimental and theoretical results obtained for the He atom beam incident along the highly corrugated $[ 1\bar{1}0 ]$ direction of the $\beta_{2}$(2$\times$4) reconstructed GaAs(001) surface are summarized and complemented by the measurements and calculations for the beam incidence along the weakly corrugated [010] direction where a periodicity twice smaller as expected is observed. The combination of the experiment, quantum scattering matrix calculations, and semiclassical analysis allows in this case to reveal structural characteristics of the surface. For the in situ measurements of GIFAD during molecular beam epitaxy of GaAs on GaAs surface we analyse the change in elastic and inelastic contributions in the scattered beam, and the variation of the diffraction pattern in polar angle scattering. This analysis outlines the robustness, the simplicity and the richness of the GIFAD as a technique to monitor the layer-by-layer epitaxial growth.