Characterization of Milled High-Pressure High-Temperature NV-Center Nanodiamonds for Single-Photon Source Applications

The color centers in nanodiamonds are promising candidates for the fabrication of stable roomtemperature sources of single photons. We investigate the luminescent and morphological properties of milled high-pressure high-temperature nitrogen-vacancy (NV) center nanodiamonds with sizes of similar to 10 - 160 nm on a glass substrate. We carry out the studies of photoluminescence and Raman spectra of a nanodiamond powder under excitation at wavelength lambda(0) = 532 nm and demonstrate the presence of luminescence of NV- and NV0 centers, as well as fundamental diamond Raman peak (1332 cm(-1)). Laser scanning confocal fluorescence microscope images of NV centers under 532 nm CW excitation show the single-emitter behavior of these centers. The second-order correlation functions g((2))(t) for one or several (2-4) emitting NV centers are measured. We receive minimum g((2))(0) = 0.15 with background correction and estimate the photoluminescence lifetimes of NV centers from 10 to 25 ns. For a single NV center, we obtain the saturation count rate of similar to 250 kcounts/s.