Fabrication of unbacked ultra-thin films of beryllium and other metals

A method is given for preparing ultra-thin unbacked metal films by evaporating the metal onto rock-salt platelets coated with a thin layer of a soluble thermoplastic resin. Beryllium films have been made with thickness ranging from 0.2 to 0.5 μm and free from “optical” pinholes. The beryllium was rapidly and continuously evaporated from a tungsten crucible with very little corrosion of the crucible. Deposition rates of 100 nm s^-1 were achieved with a source-to-substrate distance of 140 mm.