Effects of simultaneous boron and nitrogen addition on hot-filament CVD diamond growth

The observed boron and nitrogen incorporation probabilities and fiends on the morphology of CVD diamond layers suggest differences in the mechanisms of the involved species. As knows fi-om previous works, higher N concentrations added alone result in unfaceted microcrystalline diamond with increasing amorphous carbon content, High B addition favors graphitic features in the depositions. To Set further insight and to investigate interactions between these elements, simultaneous addition of both was considered. Investigated ranges (ratio in the gas phase) were: B/C, 1100-11000 ppm; N/C, 0.2-4; The main influence of a simultaneous addition of B and N was the graphite formation side by side with diamond during deposition. With boron being added, the temperature to favor graphite formation was lowered considerably. Small nitrogen amounts increased the formation of graphite. On the other hand, under highly boron-doped deposition conditions, large amounts of nitrogen stabilized the diamond phase. formation of hexagonal boron nitride or other phases was not observed. (C) 1997 Elsevier Science S.A.