Impact of Surface Roughness on Ion-Surface Interactions Studied with Energetic Carbon Ions 13C on Tungsten Surfaces+

Abstract

The effect of surface roughness on angular distributions of reflected and physically sputtered particles is investigated by ultra-high vacuum (UHV) ion-surface interaction experiments. For this purpose, a smooth (R a = 5.9 nm) and a rough (R a = 20.5 nm) tungsten (W) surface were bombarded with carbon ions 13C+ under incidence angles of 30 ∘ and 80 ∘ . Reflected and sputtered particles were collected on foils to measure the resulting angular distribution as a function of surface morphology. For the qualitative and quantitative analysis, secondary ion mass spectrometry (SIMS) and nuclear reaction analysis (NRA) were performed. Simulations of ion-surface interactions were carried out with the SDTrimSP (Static Dynamic Transport of Ions in Matter Sputtering) code. For rough surfaces, a special routine was derived and implemented. Experimental as well as calculated results prove a significant impact of surface roughness on the angular distribution of reflected and sputtered particles. It is demonstrated that the effective sticking of C on W is a function of the angle of incidence and surface morphology. It is found that the predominant ion-surface interaction process changes with fluence.

Keywords

• roughness
• ion-surface interaction
• angular distribution
• reflection
• physical sputtering
• deposition
• sticking
• plasma-wall interaction
• secondary ion mass spectrometry
• nuclear reaction analysis
• SDTrimSP