Highly intensive emission of the NV- centers in synthetic HPHT microdiamonds at low nitrogen doping

Synthetic high-pressure high-temperature (HPHT) microdiamonds demonstrate strong resonant-like enhancement of the NV- photoluminescence (PL) at unexpectedly low concentration of the substitutional nitrogen atoms (N-s) of 90 ppm, which is significantly smaller than the similar to 250 ppm characteristic for conventional HPHT synthesis. The EPR, Raman, and luminescent spectroscopies, including time-resolved PL, provide evidence that this is due to competition between the increase in PL with increasing concentration of the NV- centers and nonradiative deactivation of these centers by defects induced by the N-s in the diamond crystal lattice. It is suggested that the intensity of the NV- center emission can be optimized by the appropriate choice of nitrogen doping concentration which does not substantially disrupt the diamond crystal lattice. (C) 2018 Author(s).