Идентификация NV-центров в синтетических флуоресцентных наноалмазах и контроль дефектности кристаллитов методом электронного парамагнитного резонанса

A 100 nm synthetic diamond particle with a large (> 4 ppm) amount of nitrogen vacancy (NV) centers has been studied. The latter exhibit lines associated with forbidden Delta m_s = 2 and allowed Delta m_s = 1 transitions in the electron paramagnetic resonance (EPR) spectra of the ground state of the NV(-) center. The luminescence intensity of particles in the range 550-800 nm increases with an increase in the irradiation dose of 5 MeV electrons and correlates with the integrated intensity of the EPR line with a g-factor g = 4.27.This value is used to estimate the concentration of NV(-) centers and to select diamond powders with the highest fluorescence intensity. The dependence of the EPR signal intensity of the Delta m_s = 2 transition of the NV(-) center on the microwave power has the form of a curve with saturation and subsequent decay, and rather well characterizes the crystal quality of the local environment of the centers under study in these particles. The intensity of the x,y Delta m_s = 1 transition (at ~281.2 mT, 9.444 GHz) turns out to be more sensitive to changes in particle size in the submicron range and the appearance of near-surface defects obtained during mechanical processing.

Ensemble Negatively-Charged Nitrogen-Vacancy Centers in Type-Ib Diamond Created by High Fluence Electron Beam Irradiation

Electron beam irradiation into type-Ib diamond is known as a good method for the creation of high concentration negatively-charged nitrogen-vacancy (NV−) centers by which highly sensitive quantum sensors can be fabricated. In order to understand the creation mechanism of NV− centers, we study the behavior of substitutional isolated nitrogen (P1 centers) and NV− centers in type-Ib diamond, with an initial P1 concentration of 40–80 ppm by electron beam irradiation up to 8.0 × 1018 electrons/cm2. P1 concentration and NV− concentration were measured using electron spin resonance and photoluminescence measurements. P1 center count decreases with increasing irradiation fluence up to 8.0 × 1018 electrons/cm2. The rate of decrease in P1 is slightly lower at irradiation fluence above 4.0 × 1018 electrons/cm2 especially for samples of low initial P1 concentration. Comparing concentration of P1 centers with that of NV− centers, it suggests that a part of P1 centers plays a role in the formation of other defects. The usefulness of electron beam irradiation to type-Ib diamonds was confirmed by the resultant conversion efficiency from P1 to NV− center around 12–19%.

Optical detected magnetic resonance of nitrogen-vacancy centers in vertical diamond Schottky diode

Diamond solid-state devices are very attractive to electrically control the charge state of Nitrogen-Vacancy (NV) centers. In this work, Vertical p-type Diamond Schottky Diode (VDSDs) is introduced as a platform to electrically control the interconversion between the neutral charge NV (NV0) and negatively charged NV (NV-) centers. The photoluminescence (PL) of NV centers generated by ion-implantation in VDSDs shows the increase of NV- Zero Phonon Line (ZPL) and phonon sideband (PBS) intensities with the reverse voltage, whereas the NV0 ZPL intensity decreases. Thus, NV centers embedded into VDSDs are converted into NV- under reverse bias voltage. Moreover, the optically detected magnetic resonance (ODMR) of NV- exhibits an increase in the ODMR contrast with the reverse bias voltage and splitting of the resonance dips. Since no magnetic is applied, such a dip splitting in ODMR spectrum is ascribed the Stark effect induced by the interaction of NV- with the electric field existing within the depletion region of VDSDs.

Investigation of a single-photon hybrid emitting system based on NV-centers in nanodiamonds integrated with GaP NWs

NV-centers can be used for quantum informatics, quantum communication and quantum sensing. The calculation of optical modes formed in a GaP cylindrical nanocavity covered by nanodiamonds has been performed. GaP nanowires have been synthesized with molecular beam epitaxy and played the role of optical resonators for light-emitting centers on the base of nanodiamonds with NV-centers. The optical characteristics of the GaP-based nanocavity were analyzed. The increase in the rate of spontaneous emission of NV-centers optically coupled to the nanocavity was estimated by the time correlated single photon counting method.