Materials Processing of Diamond: Etching, Doping by Ion Implantation and Contact Formation

We are studying contact formation, regrowth and implantation doping of natural diamond, for future applications to the fabrication of devices from thin film CVD diamond. We are characterizing thin film diamonds of other ONR contractors, using ion beam methods. In the last year we concentrated on the regrowth of ion damaged layers of diamond and the doping of diamond by implantation with Na, Li and F. We observed that complete regrowth of C ion damage diamond occurred below a critical ion dose. Above that dose, a green phase occurred, which was characterized by a golden green color and by the absence of recovery of the lattice, as measured by ion channeling. Implantation doping studies of Li, Na, and F were initiated, and show some promise for n-type doping of diamond. The diffusivity of Li in diamond was studied by neutron depth profiling. In the important area of regrowth of ion damaged diamond, we observed that a completely randomized lattice can be regrown when the damaged level is below a certain threshold value, characterized by a deposited energy equivalent to 12 Frenkel defects per cu nm, or about 7 defects. The kinetic mechanisms for regrowth under these conditions, and the influence of impurities such as F and H on the regrowth, are relevant to CVD growth. EDC