Glancing-Angle Ion Enhanced Surface Diffusion on GaAs(001) during Molecular Beam Epitaxy

Abstract

We describe the effects of glancing incidence 3-4 keV Ar ion bombardment on homoepitaxial growth on vicinal GaAs(001). The average adatom lifetime on surface terraces, measured during growth using specular ion scattering, decreased monotonically with increasing ion current density. The results indicated that surface diffusivity was increased by the ions. The ion beam also suppressed growth oscillations and decreased the film surface roughness. This indicates a change from two-dimensional island nucleation to step-flow growth due to increased adatom surface diffusivity. A simple model, involving direct momentum transfer from ions to adatoms, is shown to be consistent with the measured enhanced diffusion.

Direct measurement of curvature-dependent ion etching of GaN

“…After light ion bombardment a dimple or pit density of 2.5ϫ 10 9 cm −2 was observed, which is roughly the expected dislocation density of the film. Similar structures were observed by Parkhomovsky et al, with MBE growth using NH 3 . In this case with only etching there were densities comparable to those observed after light growth.…”

“…Ion bombardment of surfaces can modify the growth kinetics of thin films [1][2][3][4] by affecting the stability of small islands, 5,6 the diffusion of adatoms, 2 vacancy and adatom creation with intra-and interlayer transport, 7 and step-edge destabilization. 8 These same processes can enter into ion etching, allowing control of surface nanostructure [9][10][11] and often producing well-defined ripple morphologies.…”

Grazing incidence impact of ions on an adatom-covered surface: Molecular-dynamics study of sputtering, surface-damage formation and ion-induced adatom mobility

“…While in the studies of glancing-ion surface interaction, it is usually stated that the interaction is strongly affected by any defects existing on the surface [7], the theoretical analysis or simulation of the interaction is often performed using binary interaction codes and concentrates on the fate of the projectile ion [8,9]. However, in the cases of structure formation under glancing-ion incidence, also the fate of the target-i.e., damage formation and sputtering-is of importance.…”

Dynamic grazing incidence fast atom diffraction during molecular beam epitaxial growth of GaAs

“…The rate of damping of the oscillations is similar to that seen with RHEED under the same growth conditions indicating that the 350 eV atom beam is not disturbing the growth unlike the case of high energy grazing incidence ion scattering where MeV ions were found to change the adatom diffusion dynamics. 11 After growth the intensity recovers, initially rapidly and then at a slower rate. This two-stage recovery process, previously observed in RHEED, has been explained as a fast process of step edge smoothing, completed within a few seconds, followed by a slower, larger scale, smoothing of the surface.…”