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

Three main areas of research were pursued in this period. The first was a continued study of the ion implantation doping of natural diamond, using dual implantations of C plus B. Of special concern was the measurement of resistance versus temperature using four point probes, to avoid edge effects and contact resistance. The result of these measurements was in general the elimination of the low activation energies occurring at the low temperature end of the resistance temperature plot, which were apparently due to small edge resistances. The second area was the attempt to dope natural diamond n-type by implantation with Na and Li, in collaboration with Oak Ridge National Laboratories. Linear Arrhenius plots of logR vs 1T were obtained, with an activation energy of near 0.4 eV. However, the resistivity was high, and it increased on annealing indicating possible effects of radiation damage. The ultimate goal of this work is the diffusion of the dopant beyond the damaged region, followed by removal of the damage by plasma etching. The third area was growth of heteroepitaxial diamond films on Cu substrates, using ion implantation of C.