Zonal and Sectorial Distribution of Impurities in HPHT Diamonds with NV Centers

A detailed analysis of spectroscopic features and of the zonal and sectorial internal structure of a multisectorial HPHT diamond sample grown in the Fe–Ni–C system is presented. The sample was irradiated by electrons with energy of 3 MeV and a dose of 1.5 × 10¹⁸ electron cm^–2 and then annealed in vacuum at 1200°C to obtain a high concentration of nitrogen-vacancy centers. Differences are established in the concentrations and incorporation forms of nitrogen in different growth sectors and of nitrogen-vacancy defects formed as a result of the treatment. Comparison of photoluminescence (PL) spectra at excitation at 488 and 785 nm and the distribution of nitrogen defects with the results of PL visualization under radiation with wavelengths of 220, 254, and 365 nm showed that photoluminescence tomography is a very informative tool for analyzing the inhomogeneity of diamond products. The Ni impurity was localized nonuniformly, many additional PL lines in the near-IR range were registered in the zones of sector {111} with high concentration of A-defects. This feature complements the defect-impurity composition of the diamond element with a high concentration of NV centers and may adversely affect the characteristics of a promising laser material.