Materials processing of diamond: Etching, doping by ion implantation and contact formation

We are studying implantation doping, etching, contact formation, and regrowth of natural diamond, for future applications to the fabrication of devices from thin film chemical vapor deposition (CVD) diamond. In addition, we are characterizing thin film diamonds of other ONR contractors, using ion beam methods. In diamond, implantation doping is difficult because the high annealing temperature necessary to remove damage and to obtain efficient dopant activation often causes graphitization. We have used an innovative co-implantation of C plus the desired dopant at 77 K, followed by rapid thermal annealing (RTA) or furnace annealing, to overcome this problem. The removal of surface layers of diamond by polishing or chemical etching is hampered by its extreme hardness and chemical inertness. We have demonstrated that reactive ion etching with O is an effective method of removing controlled amounts of diamond. We have developed a new sputtering method of forming strong metallic contacts to diamond at ambient temperatures, which may prove invaluable for microelectronics and heat sink applications. Factors affecting epitaxial regrowth of damaged natural diamond are crucial for both ion beam doping and CVD growth. We have successfully regrown C-ion implanted natural diamond layers by RTA or furnace anneals.