Angular dependence of the sputtering yield of rough beryllium surfaces

A new approach to study the influence of target surface roughness on sputtering is applied for two differently prepared beryllium surfaces. The topography of the Be surfaces are monitored with a scanning tunnelling microscope (STM). Mathematical methods are used to determine a distribution of local angles of incidence for a given nominal angle of incidence; this distribution is taken as input for the Monte Carlo program TRIM.SP far the calculation of the sputter yield of rough surfaces. Additionally, the redeposited fraction of emitted atoms on the rough surface is taken into account. The calculated results are compared with the calculation for an atomically smooth surface and experimental sputter yields. Results are given for deuterium and helium, and selfbombardment at 0.3 and 3 keV and several angles of incidence for rough Be surfaces. (C) 1999 Elsevier Science B.V. All rights reserved.