Using grazing-angle ion bombardment for surface modification rather than conventional near-normal incidence ions has the advantages of reducing damage and implantation projected ranges and preferentially removing surface asperities leading to flat surfaces [1]. Application of grazing angles of incidence of ions on the solid surface opens new perspectives in the investigation of composition, structure and topography of real surfaces and their modification and polishing by ion beams [2].
In present work the peculiarities of preferential sputtering at 0.5-5 keV Ne grazing ion bombardment of SiC(001) and GaAs(001) surfaces and their application for the modification of surface structures have been investigated by computer simulation. The sputtering has been simulated in the primary knock-on regime. Only the primary knock-on recoil atoms ejected from first, second and third layers have been considered. The sputtering yields, subdivided into sputtering by each components and surface layers of compounds versus an initial energy of incident ions (E = 0.5-5 keV) and an angle of incidence (0-30°) counted from a target surface have been calculated.
At grazing incidence the component of projectile velocity which is normal to the surface is comparatively small. As a result the ions of primary beam penetrate only in several nearest to surface atomic layers during the process of their movement in channels of along a surface. As a result, the energy spectrum of formed slow recoil atoms is narrow and its maximum is located within the interval ΔE = 1-10 eV.
It was found that the possibility of preferential sputtering of one component essentially depends on the bombardment angle. At small glancing angles the preferential sputtering of heavy component atoms is possible. Such sputtering can result in enrichment of a surface with atoms of easy components.
The relative contributions of each component and layer to the total yield depend on the energy of incident ions and on the angle of incidence. In the whole calculated energy and angular range the contributions of sputtering from first layer are dominant.
[1] J. G. C. Labanda and S. A. Barnett, Journ. of Electronic Mater. 26, 1030 (1997).
[2] A. A. Dzhurakhalov, Nucl. Instr. & Meth. in Phys. Res. B 216, 202 (2004).
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