Pustaka Ilmiah Universitas Padjadjaran

Abstrak

Influence Of A Single Adatom On Sputtering At Grazing Incidence – A Molecular-dynamics Case Study Of 5 keV Ar Impact On Pt (111)

Grazing incidence ion impact on a ?at terrace lets the projectile re?ect specularly off the surface, leading to little or no damage production or sputtering. The presence of isolated surface defects may change this behaviour drastically. We investigate this phenomenon for the speci?c case of 5 keV Ar ions impinging at 83 o towards the surface normal onto the Pt (111) surface. Molecular-dynamics simulations allow to study the in?uence of isolated adatoms in detail. The scattering of the projectile from the adatom can redirect the projectile, or let the adatom recoil, such that either of them deposits considerable energy in the target surface, leading to abundant damage production and sputtering. Two distinct collision zones are identiflied: (i) When the projectile hits the surface in front of the adatom, it may collide with the adatom indirectly (after being specularly re?ected off the surface); (ii) alternatively, it may hit the adatom directly. We quantify our results by measuring the zone of in?uence (= 13 Å2) around the adatom, into which the projectile must hit in order to collide with the adatom, and by the sputter cross section of roughly 110 Å2. The data compare well with previous simulation results of sputtering from an atomically rough surface.