Nitrogen Desorption and Positron Sensitive Defect of CVD Diamond (original) (raw)
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Nowadays, diamonds are widely used in science and technology. However, the properties of diamonds due to their defects are not fully understood. In addition to optical methods, positron annihilation spectroscopy (PAS) can be successfully used to study defects in diamonds. Positrons are capable of detecting vacancies, small and large clusters of vacancies induced by irradiation, by providing information about their size, concentration, and chemical environment. By mapping in the infrared (IR) range, it is possible to consider the admixture composition of the main inclusions of the whole plate. The article presents the results of the study of defects in synthetic diamond plates, one of which was irradiated by electrons. Presents data about the distribution of the defect concentration obtained by Infrared spectroscopy. PAS with a monochromatic positron beam can be used as a non-destructive technique of detecting defects (vacancy) distribution over the depth of diamond plates.
Physical Review B, 2011
We studied the parameters to optimize the production of negatively-charged nitrogen-vacancy color centers (NV −) in type 1b single crystal diamond using proton irradiation followed by thermal annealing under vacuum. Several samples were treated under different irradiation and annealing conditions and characterized by slow positron beam Doppler-broadening and photoluminescence (PL) spectroscopies. At high proton fluences another complex vacancy defect appears limiting the formation of NV −. Concentrations as high as 2.3 × 10 18 cm −3 of NV − have been estimated from PL measurements. Furthermore, we inferred the trapping coefficient of positrons by NV −. This study brings insight into the production of a high concentration of NV − in diamond, which is of utmost importance in ultra-sensitive magnetometry and quantum hybrid systems applications.
Study of defects in CVD and ultradisperse diamond
Diamond and Related Materials, 1999
Characterization of defects in chemical vapor deposition (CVD) and detonation synthesis ultradisperse diamond ( UDD) is reported. Electron Spin Resonance, Raman, and photothermal deflection spectroscopies show that sp2-bonded carbon is a dominant defect in UDD diamond. Although UDD was made from trinitrotoluene, no substitutional nitrogen was detected. Photoluminescence (PL) from CVD films showed narrow lines at 1.68, 1.945 and 2.156 eV, in addition to broad red and green bands, while only a blue band was observed in UDD samples. On the basis of PL excitation measurements, the green band in CVD diamond is attributed to donor-acceptor pair recombination. On the basis of a spatial variation of PL intensity in CVD films, the incorporation mechanism for silicon, nitrogen, and boron atoms is discussed.
Nitrogen-related dopant and defect states in CVD diamond
Physical Review B, 1996
Subbandgap absorption of chemical-vapor-deposition diamond films, with nitrogen contents varying from 10 to 132 ppm has been explored by the constant-photoconductivity method ͑CPM͒, photothermal-deflection spectroscopy ͑PDS͒ and electron spin resonance ͑ESR͒. The spectra measured by PDS increase monotonically and are structureless with increasing photon energies indicating absorption due to amorphous carbon and graphite. The CPM data show distinct features, with absorption bands at hϭ1.6, 4.0, and 4.7 eV in the nominally undoped film, and 2.4 and 4.7 eV in nitrogen-rich layers respectively. The CPM spectra of the doped films are comparable to photoconductivity data of synthetic Ib diamond. The defect densities involved increase with increasing nitrogen content. From ESR, a vacancy-related defect density (gϭ2.0028) is deduced. Paramagnetic nitrogen (gϭ2.0024) can be detected in the high-quality CVD layer or by illuminating the nitrogenrich samples with photon energies larger than the band gap. ͓S0163-1829͑96͒09535-5͔
Applied Radiation and Isotopes, 2008
Three types of diamonds produced by chemical vapor deposition (CVD) and broadly classified as detector grade, optical grade and single crystal were evaluated in terms of their response to a-particle radiation when used as detection elements. It is well known that the presence of defects in diamond, including CVD specimens, not only dictates but also affects the response of diamond to radiation in different ways. In this investigation, tools such as electron spin resonance (ESR), thermoluminescence (TL), Raman spectroscopy and ultraviolet (UV) spectroscopy were used to probe each of the samples, which were then graded on their performance as a-particle radiation detectors. The presentation discusses the presence of defects identifiable by the techniques used and correlates the radiation performances of the three types of crystals to their presence.
Formation of optical centers in CVD diamond by electron and neutron irradiation
Diamond and Related Materials, 1992
An investigation of the formation of optical centers in chemical vapor deposited diamond (CVD diamond) by electron and neutron irradiation has been carried out. Cathodoluminescence was mainly used for observation of the optical centers. Several optical centers have been observed after the irradiation and subsequent annealing at 900 °C, such as the 5RL center and the centers with zerophonon lines at 3.19 eV, 2.16 eV and 1.94 eV. Because these centers are considered to have relations to nitrogen atoms, vacancies or interstitials, it is expected that their luminescence intensities depend on the amount of nitrogen doping and radiation dose. However, decrease in the luminescence intensity with the amount of nitrogen doping has been observed. Boron-doped specimens have also been irradiated and annealed, but the formation of defects related to boron has not been observed.
Photoluminescence Decomposition Analysis: A Technique to Characterize N - V Creation in Diamond
Physical Review Applied
Treatment of lab-grown diamond by electron irradiation and annealing has enabled quantum sensors based on negatively-charged nitrogen-vacancy (NV-) centers to demonstrate record sensitivities. Here we investigate the irradiation and annealing process applied to 28 diamond samples using a new ambient-temperature, all-optical approach. As the presence of the neutrally-charged nitrogenvacancy (NV 0) center is deleterious to sensor performance, this photoluminescence decomposition analysis (PDA) is first employed to determine the concentration ratio of NVto NV 0 in diamond samples from the measured photoluminescence spectrum. The analysis hinges on (i) isolating each NV charge state's emission spectrum and (ii) measuring the NVto NV 0 emission ratio, which is found to be 2.5˘0.5 under low-intensity 532 nm illumination. Using the PDA method, we measure the effects of irradiation and annealing on conversion of substitutional nitrogen to NV centers. Combining these measurements with a phenomenological model for diamond irradiation and annealing, we extract an estimated monovacancy creation rate of 0.52˘0.26 cm-1 for 1 MeV electron irradiation and an estimated monovacancy diffusion coefficient of 1.8 nm 2 /s at 850˝C. Finally we find that irradiation doses Á 10 18 e-/cm 2 deteriorate the NVdecoherence time T2 whereas T1 is unaffected up to the the maximum investigated dose of 5ˆ10 18 e-/cm 2 .
Diamond and Related Materials, 2004
Coincidence Doppler broadening studies (CDB) have been carried out on CVD diamond films. The coincidence Doppler broadened spectra are analyzed to obtain information about the chemical surroundings at the annihilation site. Remarkably large fraction of positrons are seen to annihilate with the nitrogen present as impurity in low concentration. Complementary positron lifetime (LTS) measurements indicate saturation trapping of positrons, primarily in monovacancies and vacancy clusters. The information obtained from CDB and LTS studies provides direct observation of nitrogen decorated vacancies or nitrogen vacancy complexes in diamond film. Our results highlight the potential of CDB technique in characterizing impurity precipitates and impurity vacancy complexes in diamond. D