Sputtering of silicon at glancing incidence

Recent experimental sputtering yield data for Si sputtered by 30 keV Ga FIB shows a discrepancy with binary collision (BC) simulations for angles greater than 85°. This study investigates the factors of BC simulations that could be responsible for the discrepancy at glancing angles, including surface roughness, Ga implantation, electronic stopping, and surface binding energy. It is concluded that the dominant factor at glancing angles is surface roughness. Two roughness models, sinusoidal and pink noise, are used to demonstrate that very small amplitude (∼2 Å) roughness is required to obtain quantitative agreement with experiments at very glancing angles. Furthermore, it is shown that large amplitude roughness should be unstable under glancing angle beams.