Sputtering on He cooled substrate: a new method for producing nanometre-size materials

A multi-opposed targets sputtering system with a substrate cooled by liquid helium is proposed as a novel method for preparing small particles and nanocrystalline composites. Three pairs of targets are supplied with both dc and rf power supplies. All of the materials including ceramics and polymers, can be sputtered simultaneously. ring of the various target materials is accompanied by a properly controlled process in which the media gas (Ar, for example) is solidified. The sputtered particles are embedded into the solid inert gas matrix on the substrate. After the sputtering is terminated, the substrate temperature and the pressure are increased; the solid argon is liquified and, together with the particles, collected in the container. However, such particles are not stable. They aggregate rapidly in liquid argon and coalesce spontaneously after the argon is evaporated. The application of this inert-gas matrix isolation technique allows us to produce free-standing particles of low contamination metal-metal, metal-ceramic, and metal-polymer composites at low temperatures (below 84 K). Addition of other gases makes it possible to react or stabilize the particles. In this way a new route for the synthesis of novel phases of nano-sized materials is achieved.