Vacuum-deposited capacitors

In recent years it has become possible to prepare by evaporation thin dielectric films suitable for use in capacitors. Films of other materials (magnetic, resistive, conductive) are familiar from their uses in computers and other applications. The evaporation of materials which are suitable for dielectrics has been developed on a large scale by the optical industry for lens blooming, interference filters and protective coatings. Their application to electrical uses however has been slow. A number of problems, both fundamental and practical, remain to be solved before the evaporation processes become suitable for large-scale use in every case. The use of very thin films permits very high capacitance in a small space whilst allowing rapid discharge.