Surface modifications and erosion yields of silicon and titanium doped graphites due to low energy D+ bombardment

Influences of low energy D+ ion bombardment and target temperature on surface topography, surface concentration and erosion yield of carbon based binary compounds were investigated. The samples contained 10 at.% Si and 10 at.% Ti, respectively. The surface concentration was determined in situ by Auger electron spectroscopy and the topography ex situ by scanning electron microscopy. During low energy D+ bombardment a pronounced conelike surface developed with silicon respective titanium rich ''caps'' protecting the underlaying carbon rich shafts from erosion. The average dopant surface concentration was up to 7 x the bulk concentration. The erosion mechanism was determined by surface concentration and chemical state of the surface: At high temperatures carbidic bindings dominated, while at room temperature a mixture of graphite and carbide covered the surface. (orig.)