AN APPARATUS FOR GLANCING INCIDENCE ION-BEAM POLISHING AND CHARACTERIZATION OF SURFACES TO ANGSTROM-SCALE ROOT-MEAN-SQUARE ROUGHNESS

An instrument is described which combines a glancing incidence ion bea m erosion system with a scanning tunneling and an atomic force microsc ope. This instrument allows the ion beam polishing and surface topogra phic characterization of conducting and insulating, crystalline, polyc rystalline, and amorphous samples under ultrahigh vacuum conditions. A s an illustration of the capability of the instrument and the polishin g technique, we present results demonstrating a fivefold improvement i n rms roughness of a polycrystalline Cr film and a fivefold reduction in rms roughness of a vicinal, initially mechanically polished CaF2 (1 11) sample. The final rms roughness of the latter sample of 0.12 +/- 0 .04 nm measured over the bandwidth of 10-500 nm is just 75% of the Ca- F interlayer spacing for the (111) surface orientation. (C) 1996 Ameri can Institute of Physics.