Effect of CVD diamond growth by doping with nitrogen

The purpose with the present investigation has been to support and explain the experimental observation made regarding the enhancing effect by N doping on especially the diamond (100)-2 × 1 growth rate. Within the present study, also the commonly observed diamond (111) and (110) surfaces were included, all assumed to be H-terminated. Density functional theory calculations were used, based on a plane wave approach under periodic boundary conditions. It was shown that the surface H abstraction reaction is most probably the rate-limiting step during diamond growth. In addition, the results showed that it is N, substitutionally positioned within the upper diamond surface, that will cause the growth rate improvement, and not nitrogen chemisorbed onto the growing surface in the form of either NH (or NH 2 ). The here presented numerical value for the growth rate enhancement for the diamond (100)-2 × 1 surface is almost identical with the experimentally obtained one (3.7 vs. 3.6). In addition, the (111) and (110) surfaces were shown to undergo a different growth rate enhancement, with about half as much for the (111) and (110) surfaces as compared to the diamond (100)-2 × 1 surface (1.9, 1.7 vs. 3.7). Despite the rate improvement for all surface planes, this difference will bring about a preferred diamond (100) surface texture.