Influence of surface morphology on the angular distribution and total yield of copper sputtered by energetic argon ions

The angular distribution of 40-keV-argon-sputtered copper has been measured by collecting the copper on a semicircular superpure aluminum foil and later analyzing by 1.8-MeV-He backscattering. Comparison has been made of the distributions from a flat surface of (11 3 1) copper and a pyramid-covered surface of the same orientation. The overall yield from the pyramid-covered surface is ∼50% greater than from the flat. This result is in contradiction to earlier reports of sputtering yields from flat and rough surfaces. Directional effects of sputtering are observed from both flat and pyramid-covered surfaces with enhancement by a factor of ∼4 in the latter case.