Study of low energy sputtering of Pt(111) surface by molecular dynamics simulation

Low energy sputtering of Pt (111) surface by noble metal atoms with the incident energy in the range of 0.1 — 200 eV has been studied by molecular dynamics sim ulation. The atomic interaction potential with embedded atom method (EAM) was us ed in the simulation. It was found that the sputtering threshold energy is indep endent of the mass of the incident atom in the case of normal impact on the Pt ( 111) surface. When the incident energy is lower than the threshold energy, the b ehavior of incident atom can be regarded as deposition process. When the inciden t energy is higher than the threshold energy, however, the sputtering yield incr eases with the increase of the incident energy. For the incident energy of 200 e V, the sputtering yield induced by various incident atoms approaches 1 or even h igher. The results mean that the atom with incident energy higher than 200 eV ma inly plays the role of sputtering. The probability of angular distribution of th e sputtered atoms and the sputtering pattern are similar to the sputtering resul ts with higher incident energy. We found that the sputtering yield is a function of the reduced energy of incident atom and the mass ratio of incident atom to t arget atom when the incident energy is higher than the threshold energy, which i s different from the linear cascade theory based on the binary collision model. We suggest a new physical mechanism for low energy sputtering, where the reflect ion of incident atom by target atom dominates the sputtering process of surface atoms.