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Plasma Materials Processing at U of S

Work is being done in the following areas:

Plasma Assisted Materials Synthesis and Processing (Bradley, Hirose, Xiao, Yang)

Research on plasma assisted material synthesis and processing was initiated in the Laboratory four years ago. Carbon nanostructures (diamond films, carbon nanotubes (CNT), carbon nanocones) have been successfully synthesized with a newly developed ion sputtering technology which allows diamond synthesis at unusually low temperatures (as low as 250 C). Several methods have been developed for mass production of carbon nanotubes and the Laboratory is collaborating with a group in Chemical Engineering on industrial applications of CNT. In biomedical applications of diamond and related materials, DLC (diamond-like-carbon) has been coated on polymers (PTFE) to improve its haemocompatibility. (PTFE tubes used in cardiovascular applications tend to develop blood clotting if the diameter is less than 6 mm.) Haemocompatibility tests of PTFE with and without DLS coating have been conducted with human blood. Preliminary results are encouraging: DLC coating reduces platelet activation and adhesion. Field electron emission from the synthesized carbon nanostructures has also been observed. One of the long term objectives of the research is to develop a synthesis technology for diamond semiconductors. Superiority of diamond based semiconductors over silicon based semiconductors is well known but development of fabrication technology has been slow. Another area of high priority is research on super hard composite materials for applications in mechanical and nuclear engineering.

Ion Implantation (Bradley)

Plasma ion implantation is an innovative material modification technique whereby controlled quantities of desired impurities are implanted into target materials by applying high-voltage negative pulses to a target immersed in a plasma (a gas of ions and electrons) composed of the ions to be implanted. Material properties are highly dependent on the composition and distribution of impurities within the material; because it allows precisely controlled insertion of impurities at controlled depths, plasma ion implantation is one of the most versatile techniques available for the modification of material properties. A proof-of-concept high-voltage pulser has been designed and built, and is now being tested in the ICP plasma chamber recently acquired by the Laboratory. Preliminary results are encouraging. This high-voltage pulser will be used for high-dose ion implantation of a variety of sample materials, such as conventional and porous silicon, SiO2, and diamond and DLC films.

Magnetic Processing