CVD single crystal diamond

Abstract

A single substituted nitrogen atom, N, in the neutral charge state as measured by EPR s 0 CVD single crystal diamond with a concentration of 0.25 to 3 ppm, and nitrogen vacancy centers (NV 0 and N.V. - ) is the total concentration of N s 0 CVD single crystal diamond, with a concentration of 0.1 to 0.8 times that of

Description

[Technical Field]

[0001] The present invention relates to CVD single-crystal diamond and a method for producing CVD single-crystal diamond. [Background technology]

[0002] In the 1980s and 90s, numerous experiments targeting the synthesis of single-crystal CVD diamond materials were conducted by various groups around the world. Much of this research disclosed the growth of thin layers of single-crystal CVD diamond material on single-crystal diamond substrates by homoepitaxial growth. While there was a demand for producing relatively thick layers of high-quality single-crystal CVD synthetic diamond material, it was clear that achieving this in practice was difficult. The synthesis of single-crystal CVD diamond material requires extreme conditions. To successfully grow thick layers of high-quality single-crystal CVD synthetic diamond material, these conditions must be generated and maintained stably over a long period of time. Furthermore, the properties of the diamond material to be synthesized are influenced by numerous synthesis parameters that form a complex multidimensional synthesis parameter space. Only a small range within this multidimensional synthesis parameter space can achieve thick layers of high-quality single-crystal CVD diamond material. Identifying these synthesis regions and developing methods to generate the correct combination of parameters necessary to produce and maintain stable growth within one of these synthesis regions is by no means trivial. The synthesis parameters crucial for single-crystal CVD diamond growth include the substrate type (e.g., whether manufactured by CVD, under high pressure / high temperature, or natural geological synthesis), the method of preparing the substrate from the original matrix crystal, the substrate morphology (including crystal orientation of faces and / or edges), the substrate temperature during growth and thermal control of the growing crystal, and the vapor phase synthesis environment itself. The latter is influenced by the process gas composition (including impurities), the gas pressure within the process chamber, and the amount of microwave power supplied to the synthesis process, in addition to various mechanical factors such as the size of the process chamber, the process gas injection / exhaust morphology, and the process gas flow rate. Many of these parameters are interrelated so that if one parameter changes, others change accordingly, ensuring a suitable growth area. Failure to select and maintain suitable process conditions for the entire deposition area throughout the entire synthesis process can result in high levels of uncontrolled process variability, unusable products with unsuitable material properties, and even complete destruction of the crystal due to catastrophic cracking, twinning, or graphitization.

[0003] It is known that defects are intentionally added as dopants. Since providing nitrogen to the CVD process gas has been found to increase the growth rate of the material and may also influence the formation of crystal defects such as dislocations, nitrogen is one of the most important dopants in the synthesis of CVD diamond materials. Therefore, nitrogen doping of single-crystal CVD-synthesized diamond materials has been extensively studied and reported in the literature. For some applications, such as electronic applications, it has been found advantageous to develop techniques for intentionally excluding nitrogen from the CVD process gas. However, for other applications, a substantial level of nitrogen doping can yield advantageous properties and / or may be useful in achieving thicker layers of CVD-synthesized diamond materials. An example of patent literature relating to such nitrogen-doped single-crystal CVD-synthesized diamond materials is International Publication No. 2003 / 052177. Intrinsic diamond material has an indirect band gap of 5.5 eV and is transparent in the visible portion of the spectrum. By introducing defects with relevant energy levels within the band gap, i.e., color centers, diamond exhibits a characteristic color depending on the type and concentration of color centers. This color can be due to either absorption or photoluminescence, or several combinations of these two. Generally, absorption is the primary factor. An example of a common color center present in synthetic diamond material is nitrogen. When nitrogen is in a substitutional lattice position in a neutral charge state, it has a relevant energy level of 1.7 eV, lower than the conduction band, causing absorption at the blue edge of the visible spectrum, and alone diamond has a characteristic yellow color. When the nitrogen atom is in a substitutional lattice position in a neutral charge state, N s 0 It is known as a defect, and its concentration is [N s 0 This is indicated by ].

[0004] For example, according to International Publication No. 2010 / 149775, single-substituted nitrogen N s 0 Irradiation and annealing of CVD diamond materials containing [specific compound] is known to produce pink diamonds. The term "fancy color diamond" is an established gem trade classification used to refer to diamonds that are unusually colored. Examples of synthetic and natural diamonds with fancy colors produced by introducing color centers into diamonds are known in the art. For example, European Patent Publication No. 0615954 and European Patent Publication No. 0316856 describe irradiating a synthetic diamond material with an electron beam or neutron beam to form lattice defects (interstitial atoms and vacancies) in the crystal. The diamond crystal is then annealed in a predetermined temperature range to form color centers. One of the described color centers is a substituted nitrogen atom adjacent to a vacancy, called an "NV center," which can impart a desired fancy color to the diamond material, such as purple (as described in European Patent Publication No. 0316856) or red / pink (as described in European Patent Publication No. 0615954). NV centers are not only useful for giving diamonds a pink color, but also have many important applications in other fields. NV centers are being studied for use in a variety of imaging, sensing, and processing applications, including, for example, light-emitting tags; magnetic sensors; spin resonance devices such as nuclear magnetic resonance (NMR) and electron spin resonance (ESR) devices; spin resonance imaging devices for nuclear magnetic resonance imaging (MRI); quantum information processing devices such as those for quantum communication and computing; magnetic communication devices; and gyroscopes. NV centers are attracting interest as useful quantum spin defects because they possess several desirable characteristics, including: (i) The electron spin state can be manipulated coherently with high fidelity and has an extremely long coherence time (transverse relaxation time T2 and / or T2 * It can be quantified and compared using this method; (ii) The electronic structure optically injects defects into their electronic ground state, placing such defects into specific electronic spin states even at non-cryogenic temperatures. This eliminates the need for expensive and large cryogenic coolers for certain applications where miniaturization is desired. Furthermore, defects can function as sources of photons, all of which have the same spin state; and (iii) Its electronic structure includes luminescent and non-luminescent electron spin states, and the electron spin state of the defect can be read out by photons. This is useful for reading information from synthetic diamond materials used in sensing applications such as magnetic measurements, spin resonance spectroscopy, and imaging. Furthermore, it is an important element for using NV defects as qubits in long-range quantum communication and scalable quantum computing. As such results, NV defects are a competing candidate for solid-state quantum information processing (QIP).

[0005] Multiple single-crystal CVD-synthesized diamonds can be produced in a single CVD growth cycle or run (meaning a single, uninterrupted growth operation in a CVD reactor) by providing multiple single-crystal diamond substrates on a substrate carrier, introducing a process gas, and forming a plasma to deposit carbon on the substrates and grow diamonds. Problems with this method of synthesizing multiple single-crystal CVD diamonds are issues of uniformity and yield. Heterogeneity can exist in terms of crystal morphology, growth rate, cracking, and impurity content and dispersion. For example, as described in International Publication 2013 / 087697, even with careful control of the CVD diamond growth chemical reaction, uneven impurity incorporation can occur due to temperature fluctuations on the growth surface that affect the impurity incorporation rate. Temperature fluctuations also cause fluctuations in crystal morphology, growth rate, and cracking. These temperature fluctuations can be lateral to the growth direction (spatially distributed) at specific points in the growth run, or parallel to the growth direction (temporally distributed) due to temperature fluctuations over the duration of the growth run. Fluctuations can occur within a single CVD diamond crystal and between crystals when multiple crystals are provided to the synthesis process. Therefore, in multiple crystal synthesis processes, only a portion of the product diamond crystals from a single growth run may meet the desired specifications.

[0006] There is little prior art that describes both growing multiple CVD single-crystal diamonds and the distribution of properties (such as hardness) that occur between the diamonds. The conditions necessary to grow multiple single-crystal diamonds with properties desirable for specific applications in high yield are mostly still unknown. Studies on the uniformity of a region are known from the perspective of polycrystalline diamond wafers or thin films, but what has been disclosed in this regard has little relation to the requirements for growing a relatively large number of substantially separated single-crystal diamonds.

Summary of the Invention

[0007] An object is to provide a method for synthesizing CVD single-crystal diamonds that can mass-produce CVD single-crystal diamonds having NV centers with a uniform concentration for quantum applications or desired applications such as pink gemstones.

[0008] According to a first aspect, a single substitution nitrogen atom N in a neutral charge state, as measured by EPR s 0 provides a CVD single-crystal diamond having a concentration of 0.25 to 3 ppm. The CVD single-crystal diamond has a total concentration of nitrogen-vacancy centers (NV 0 and NV - ) in the neutral and negatively charged states that is 0.1 to 0.8 times the concentration of N s 0 . Optionally, the CVD single-crystal diamond has at least one length dimension of 3.5 mm or more. As an option, the CVD single-crystal diamond has a hue angle h ab selected from any of -45 to 45°, -10 to 40°, and 10 to 40°. The CVD single-crystal diamond is optionally quantified by the ratio of the total peak area of the zero-phonon line of SiV - to the peak area of the primary Raman signal of the diamond in photoluminescence measurements performed at a temperature of 77 K using an excitation wavelength of 660 nm, and is selected from any of less than 0.5; less than 0.1; less than 0.05; and less than 0.01 of SiV -It exhibits luminescence. Such values ​​indicate a diamond material with very few silicon impurities. CVD single-crystal diamond exhibits low optical birefringence with low strain at an arbitrary temperature of 20°C. When measuring an area of ​​at least 3 mm × 3 mm, the third quartile of the refractive index difference of light polarized parallel to the slow and fast phase axes is averaged over the sample thickness, resulting in a value of 1 × 10⁻⁶. -4 and 5×10 -5 The values ​​must not exceed one of the following ranges. These low birefringence values ​​indicate suitable samples for producing single-crystal CVD diamonds without "grain," otherwise their perceived clarity may be affected.

[0009] As an option, the total volume of the single-crystal CVD diamond material must be at least 0.1 mm³. 2 at least 1 mm 2 , at least 10mm 2 , at least 20mm 2 , at least 40mm 3 , at least 60mm 3 , at least 80mm 3 and at least 100 mm 3 One of the following will be selected. CVD single-crystal diamonds are optionally gem-like and have a chrominance selected from 5 to 40, 10 to 35, and 15 to 30. * ab It has. The resulting diamond is used in applications that leverage the spin properties of NV centers, but in the case of CVD single-crystal diamond, the measured heterogeneous phase relaxation time T2 of the ensemble NV is measured by Ramsey pulse sequencing. * This is over 5 microseconds. CVD single-crystal diamonds are optionally gem-like and have a color grade selected from Fancy Light, Fancy, Fancy Intense, Fancy Vivid, and Fancy Deep, along with one of the following colors: Pinkish Orange, Orange-Pink, Pink, Purplish Pink, Purple Pink, and Pink Purple, according to the Gemological Institute of America (GIA) scale and method. CVD single-crystal diamonds are optionally gem-like and have clarity grades selected from VS2, VS1, VVS2, VVS1, IF, and FL according to the Gemological Institute of America (GIA) scale and methods. These clarity grades correspond to samples that are free from or have clarity defects. However, these defects are only observable under magnification and not visible to the naked eye. Some embodiments of the present invention provide single-crystal diamonds that would typically fall into one of these grades, from which gemstones formed can be sold as commercial or high-quality commodities, but are not limited to these.

[0010] CVD single-crystal diamond can optionally contain H3, NVN 0 , further including centers. Upon heat treatment, H3 centers may be formed within the disclosed material. As an option, CVD single-crystal diamond is used, and in photoluminescence measurements performed at a temperature of 77K using excitation wavelengths of 455 to 459 nm, it shows at least 50 (NV) 0 +NV - ) / H3 ratio is shown. NV 0 NV - Each of the H3 defects is quantified by the ratio of the peak area of ​​the zero-phonon line to the primary Raman signal of the diamond. CVD single-crystal diamond can be optionally selected from at least 100, at least 150, at least 200, at least 300 and at least 400 (NV 0 +NV - This shows the ratio of ) / H3.

[0011] According to the second aspect, a method for producing the multiple single-crystal CVD diamonds described above in the first aspect is provided. This method is Placing multiple single-crystal diamond substrates on a substrate carrier in a chemical vapor deposition reactor; The process gas, containing hydrogen-containing gas, carbon-containing gas, and nitrogen-containing gas, is supplied to the reactor in such a manner that the relative amount of the process gas is stoichiometrically equal to a C2H2 / H2 ratio of 1% to 4% and an N2 / C2H2 ratio of 30 ppm to 300 ppm; Growing multiple single-crystal CVD diamonds on at least some of the surfaces of multiple single-crystal diamond substrates at temperatures ranging from 750°C to 1000°C; The process involves first annealing at least a portion of the resulting single-crystal CVD diamonds at a temperature of 1500°C to 1800°C; Irradiating multiple single-crystal CVD diamonds to form vacancies in the diamond crystal lattice; This includes performing a second annealing of the resulting multiple single-crystal CVD diamonds at a temperature of 700°C to 1100°C.

[0012] The relative amount of process gas is selected so as to be stoichiometrically equal to the N2 / C2H2 ratio, which can be arbitrarily selected from 50 to 200 ppm, 60 to 180 ppm, and 70 to 150 ppm. The relative amount of process gas is selected so as to be stoichiometrically equal to a C2H2 / H2 ratio, which can be arbitrarily selected from 1 to 3%, 1.5 to 2.5%, and 1.5 to 2%. As an option, the first annealing is performed at a temperature of 1550°C to 1750°C. As an alternative, the first annealing is performed under diamond-stabilized pressure. This allows for the use of high temperatures and / or long annealing times without causing any loss or damage to the CVD single-crystal material due to graphitization. The irradiation is an electron irradiation procedure performed using an electron energy of arbitrarily selected from 1 MeV to 10 MeV. The second annealing includes annealing in a temperature range optionally selected from 700 to 1000°C, 800 to 1000°C, and 850 to 950°C. As an alternative, this method further includes cutting and polishing at least one of several single-crystal diamonds to form a gemstone. Optionally, growth on the substrate is carried out without interruption as a single CVD synthesis cycle. As an option, the process of growing multiple single-crystal CVD diamonds requires at least 10 mm 3 / h, at least 20mm 3 / h, at least 30mm 3 / h, at least 40mm 3 / h and at least 50mm 3 Provides a volume growth rate for single-crystal diamond material selected from either / h. Multiple CVD single-crystal diamonds are grown at temperatures arbitrarily selected from 800°C to 1000°C; 800°C to 950°C; and 800°C to 900°C.

[0013] According to a third aspect, an apparatus is provided that includes the CVD single-crystal diamond described in the first aspect, the apparatus being selected from an imaging device, a sensing device, a magnetic sensor; a spin resonance device, a quantum information processing device, and a gyroscope device.

[0014] The present invention will be described in more detail below with reference to the attached figures, based on the examples. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a flowchart illustrating an exemplary process for producing CVD single-crystal diamond. [Modes for carrying out the invention]

[0016] The inventors have developed mass-producible lab-grown diamond gemstone products. The invention produces dozens of single-crystal diamond materials with predictable properties, such as NV center concentration, in a single run. These properties, for example, result in a high yield of diamonds with a pink or associated GIA color grade when cut and polished into round brilliant lab-grown gemstones. The conditions developed by the inventors provide a diamond material with a relatively high growth rate and low internal strain, resulting in high yield diamond with less cracking. This is partly due to the use of a substrate with few surface defects such as etch puts. Surface defects otherwise occur as nucleation sites for a group of expanding defects, increasing strain as described in International Publication 2004 / 046427. A preferred method for achieving this is to use a vertically cut substrate as described in International Publication 2004 / 027123, the contents of which are incorporated herein by reference. This disclosure describes a method for manufacturing a single-crystal diamond plate, comprising the steps of: providing a diamond substrate having a surface substantially free of surface defects; growing diamond homoepitaxially on the surface by chemical vapor deposition (CVD); and manufacturing a single-crystal CVD diamond plate by cutting the homoepitaxial CVD-grown diamond and substrate transversely, usually perpendicular (i.e., 90° or nearly 90°) to the surface of the substrate on which diamond growth occurs. Subsequently, this single-crystal diamond plate is used as a substrate for further growth. Since expansion defects tend to propagate in the direction of growth, thinly slicing the diamond perpendicular to the growth direction ensures that the surface defect density is significantly lower on the newly sliced ​​surface.

[0017] When attempting to mass-produce lab-grown gemstones, a further problem is the perceived color inconsistency of the diamonds. Process conditions that provide perceptibly uniform color within a given gemstone, and between separate gemstones manufactured to nominally common specifications, are desirable. As described above, the presence of nitrogen can result in a yellow color. Furthermore, CVD single-crystal materials grown with a substantial amount of nitrogen typically grow rapidly and contain vacancy complexes (e.g., clusters and chains) that impart a brown hue. This brown color can be reduced or removed by heat treatment of diamond, as described in International Publication 2004 / 022821, which is incorporated herein by reference. This document describes heating diamond at a diamond stabilization pressure and a temperature exceeding 1400°C. This is known as high-pressure / high-temperature (HPHT) annealing. To form a sufficient number of NV centers to produce a pink coloration, a conventional irradiation process is performed before annealing to incorporate more vacancies into the diamond lattice than the relatively small number of vacancies that are normally incorporated during growth. During subsequent annealing, the vacancies can migrate to nitrogen within the diamond crystal lattice and form NV centers. Nitrogen can be incorporated into the diamond crystal lattice in many different ways. Some of the key methods are as follows: Single-substituted nitrogen (N s 0 ) is a single nitrogen atom that replaces a carbon atom in the diamond lattice. 1130 cm -1 It exhibits an infrared absorption band of (0.140 eV) and typically displays a brown color. Negatively charged nitrogen vacancy centers (NV) - ) is a defect, and vacancies and substituted nitrogen form pairs in a crystal lattice where the overall state is negatively charged. NV - It exhibits an absorption line at 637 nm (1.945 eV) and related bands, and usually displays a pink or purple color. The H3 center is in an overall neutral charge state (NVN). 0 It consists of two substituted nitrogen atoms separated by a vacancy. H3 shows an absorption line at 503.2 nm (2.463 eV) and related bands, exhibiting a yellow color. [Examples]

[0018] As described in International Publication No. 2004 / 027123, multiple single-crystal diamond substrates were obtained using a plate of transversely cut CVD single-crystal diamond. These were mounted on carriers and placed in a CVD reactor. A process gas was supplied to the CVD reactor. The process gas contained hydrogen, a carbon-containing gas (methane in this embodiment), and a nitrogen-containing gas (molecular nitrogen in this specification). A process gas plasma was formed in the reactor, and single-crystal CVD diamond material was grown on the surface of each of the multiple single-crystal diamond substrates to a thickness of 4 to 6 mm. Subsequently, the resulting single-crystal diamond was annealed at a pressure exceeding 6 GPa and a temperature of 1550°C to 1750°C to ensure it remained within the diamond-stable region. Prior to annealing, any polycrystalline material, along with surface cracks and defects, was removed. Otherwise, the risk of failure during annealing would increase. To maximize NV retention and avoid H3 formation, the annealing temperature was maintained at 1550°C to 1750°C for a selected time. This maximizes the pink color obtained from NV centers and produces a slight yellow from H3 centers. Below 1750°C, NV centers hardly move, but vacancies do, resulting in a lower tendency to form H3 centers. After the first (HPHT) annealing, the single-crystal diamond was electron-irradiated using electron energy from 1 MeV to 10 MeV, and then annealed again. During this process, NV centers were formed at a temperature of 700 to 1000°C. Since the temperature required for the second annealing is low, it is not necessary to perform it under diamond stabilization pressure. In this example, it was carried out in a vacuum furnace. The resulting single-crystal diamonds were cut and polished to form round brilliant gemstones, possessing either a GIA fancy color grade of "Fancy Intense Orange-Pink" or "Fancy Vivid Pink," depending on the precise synthesis and processing conditions. Furthermore, the gemstones could be cut to include a substrate, thereby reducing the time required for diamond growth. This is particularly suitable when the substrate is fabricated using the same process as the final diamond, resulting in an invisible cut.

[0019] Quantitative measurement of the finished gemstone color is difficult due to specularity, numerous internal reflections, and dispersion within the polished material. Localized highlights and apparent color flashes, primarily depending on lighting conditions, must be disregarded when evaluating the gemstone's true body color. To perform this measurement, a photographic approach described in International Publication No. 2016 / 203210 was used. This method is fast and a more reliable alternative to the use of a spectrophotometer and integrating sphere, and is therefore particularly useful when measuring many polished gemstones. When measuring a finished gemstone, the hue angle is 25°. <h ab It is within the <35° range, and most of the gemstones are h ab Strong clustering occurs around 30°. The saturation value is typically 20. <C * ab <30, and most of the measured gemstones are C * ab The values ​​were very close to the center of the range around =25. These values ​​were selected as examples. Furthermore, by suitably changing the synthesis and / or irradiation conditions, both the hue angle and saturation were adjusted to within the range of the present invention, and the N present in the finished sample was obtained. s The relative and / or absolute concentrations of NV can be changed. In this way, various aesthetic preferences can be satisfied. Excitation is performed using a 660nm diode laser, and SiV is applied at 77K. - Photoluminescence (PL) measurements were performed. Because low-temperature PL sensitivity is highest, even samples with SiV orders of magnitude lower than those detectable by absorption can be quantified. - The signal is almost always observed in measurements of CVD-synthesized diamond materials. As with other PL measurements, SiV is observed at low temperatures. - Aside from showing two ZPLs at 736.5 and 736.8 nm respectively, the recorded values ​​are SiV relative to the primary Raman line of diamond. - This is the area ratio of the PL features, and therefore SiV - 660 =I(736.5nm) / I(R1 660 ) + I(736.8nm) / I(R1 660 ) In these samples, SiV -660 The value is typically between 0.001 and 0.01, which is exceptionally small compared to the standards for commercially available CVD synthetic gemstones.

[0020] Birefringence measurements were performed on CVD single-crystal diamond material. The grown diamond material was formed into a cube. The cube had {110} oriented sides with edge lengths equal to the diagonals of the substrate, thus limiting the area of ​​the original substrate, as well as the {100} oriented top and bottom surfaces. After annealing the cube as described above, it was horizontally cut into a 0.7 mm thick plate, and both main surfaces were polished. Using a commercially available instrument (Sawlab LCC7201), the birefringence of the plate (defined as the difference in refractive index of light polarized parallel to the slow and fast axes, averaged over the thickness of the sample) was measured at a wavelength of 590 nm, and for most of its area, it was found to be well within the range of International Publication No. 2004 / 046427, which describes materials suitable for optical applications such as etalons. -5 The values ​​were on the order of 10. The exception was the region directly above the substrate edge. Dislocations tended to be concentrated at the boundaries between transverse and longitudinal growth regions, with local maximum birefringences of 10. -4 The order was as follows. While these more birefringent inclusions in the crystal may be undesirable for all technical applications, considering they occupy only a tiny fraction of the total volume, they have been found to have no detriment to the visual clarity of CVD single-crystal diamond, and in any given example, the maximum birefringence is 4.3 × 10⁻¹⁶, as cited in "Synthetic moissanite: a new diamond substitute", Gems and Gemology volume 33, issue 4, winter 1997. -2 It is less than 1% of the total. Regarding applications utilizing the spin state of NV centers in diamond, the decoherence time T2 * It can measure T2 * The value was determined by Ramsay pulse sequencing and found to be greater than 5 microseconds.

[0021] Figure 1 is a flowchart illustrating an example of the process for producing CVD single-crystal diamond. The following numbering corresponds to Figure 1. S1. Multiple single-crystal diamond substrates are placed on a substrate carrier in a CVD reactor. S2. Process gases are supplied to the reactor. The process gases include hydrogen-containing gases, carbon-containing gases, and nitrogen-containing gases. The relative amounts of these gases are stoichiometrically equivalent to a C2H2 / H2 ratio of 1% to 4% and an N2 / C2H2 ratio of 30 ppm to 300 ppm. Plasma is generated from the gases using microwaves. The relative amounts of the process gases may be selected to be stoichiometrically equivalent to an N2 / C2H2 ratio selected from 50 to 200 ppm, 60 to 180 ppm, and 70 to 150 ppm. Furthermore, the relative amounts of the process gases may be selected to be stoichiometrically equivalent to a C2H2 / H2 ratio selected from 1% to 3%, 1.5% to 2.5%, and 1.5% to 2%. S3. Single-crystal CVD diamond is grown on the surface of multiple single-crystal diamond substrates at a temperature of 750°C to 1000°C. Growth is preferably carried out as a single, continuous, uninterrupted CVD synthesis cycle or "run". The volume growth rate of this cycle is at least 10 mm 3 / h, at least 20mm 3 / h, at least 30mm 3 / h, at least 40mm 3 / h and at least 50mm 3 You may choose from either / h. The growth temperature is typically 800°C to 1000°C, 800°C to 950°C, or 800°C to 900°C. S4. The resulting single-crystal CVD diamonds are subjected to a first annealing at a temperature of 1500°C to 1800°C. At temperatures considerably higher than 1800°C, any nitrogen in the crystal may form H3 centers, meaning that single-substituted nitrogen cannot be used for the subsequent treatment to form NV centers. Those skilled in the art may choose to perform the annealing below 1750°C to further reduce the formation of H3 centers. The annealing is preferably carried out under diamond stabilization pressure to reduce the risk of graphitization. S5. Multiple single-crystal CVD diamonds are irradiated to form vacancies in the diamond crystal lattice. This may be done using, for example, electron irradiation of 1 to 10 MeV. S6. A second annealing is performed on the irradiated single-crystal CVD diamond at a temperature of 700°C to 1100°C to form NV centers. The second annealing may be performed at a temperature selected from 700 to 1000°C, 800 to 1000°C, or 850 to 950°C.

[0022] If gemstone production is desired, this method further includes cutting and polishing at least one of several single-crystal diamonds to form a gemstone. In this example, to produce a gemstone of more than 1 carat, the length dimension of at least one of the CVD single-crystal diamonds is 3.5 mm or more. However, for many technical applications, much smaller crystals, such as diamonds with at least one length dimension of 0.5 mm or more, are often sufficient. The high-yield synthesis and post-growth annealing processes described above produce multiple reproducible gemstones in a single run, significantly reducing energy costs. This allows for the production of diamonds with the required properties, with prior knowledge of the desired size and shape, and with confidence that damage during annealing will be avoided after minimal processing. Such an uninterrupted process is advantageous over "stop-start" or layer-by-layer processes, for example, by improving equipment utilization efficiency, avoiding the need to prepare multiple growth crystals, and preventing any adverse effects of interfaces formed between grown layers in the material produced by continuous growth cycles. In our preferred embodiments, as detailed in the examples, growth to full thickness is carried out substantially always without interruption.

[0023] While the present invention has been specifically illustrated and described with reference to embodiments, it will be understood by those skilled in the art that various modifications can be made in form and detail without departing from the scope of the present invention as defined in the appended claims. Another aspect of the present invention may be as follows: [1] The following, As measured by EPR, a single substituted nitrogen atom N in a neutral charge state s 0 The concentration is between 0.25 and 3 ppm; A CVD single crystal diamond having certain properties, Nitrogen vacancy centers (NV) in neutral and negatively charged states 0 and NV - The total concentration of ) is the N s 0 CVD single-crystal diamond with a concentration of 0.1 to 0.8 times the normal level. [2] The CVD single crystal diamond described in [1], having at least one length dimension of 3.5 mm or more. [3] A hue angle selected from -45 to 45°, -10 to 40°, and 10 to 40°. ab A CVD single crystal diamond according to [1] or [2] above, having the above characteristics. [4] SiV as a function of the peak area of ​​the primary Raman signal of diamond in a photoluminescence measurement performed at a temperature of 77K using an excitation wavelength of 660nm. - The SiV is quantified by the ratio of the total peak areas of zero phonon lines, selected from <0.5; <0.1; <0.05; and <0.01. - A CVD single-crystal diamond exhibiting luminescence, as described in any of [1] to [3] above. [5] When measuring an area of ​​at least 3 mm × 3 mm that has low optical birefringence exhibiting low strain at a temperature of 20°C, the third quartile value of the refractive index difference of light polarized parallel to the slow and fast phase axes is averaged over the thickness of the sample, resulting in 1 × 10⁻⁶ -4 and 5×10 -5 A CVD single-crystal diamond according to any of [1] to [4] above, which does not exceed a value selected from any of the above. [6] The total volume of the single-crystal CVD diamond material is at least 0.1 mm 2 at least 1 mm 2 , at least 10mm 2 , at least 20mm 2 , at least 40mm 3 , at least 60mm 3 , at least 80mm 3 and at least 100 mm 3 A CVD single crystal diamond according to any of [1] to [5] above, selected from any of the above. [7] Gem-like, with a saturation of C selected from 5 to 40, 10 to 35, and 15 to 30. * ab A CVD single crystal diamond according to any one of [1] to [6] above, having the following characteristics. [8] The non-uniform phase relaxation time T of the ensemble NV is measured as measured by the Ramsay pulse sequence. 2 * A CVD single-crystal diamond according to any one of [1] to [5] above, wherein the time interval is greater than 5 microseconds. [9] A CVD single crystal diamond according to any one of [1] to [7], which is gem-like and has a color grade selected from Fancy Light, Fancy, Fancy Intense, Fancy Vivid, and Fancy Deep, along with one of Pinkish Orange, Orange-Pink, Pink, Purplish Pink, Purple Pink, and Pink Purple, according to the Gemological Institute of America (GIA) scale and method.

[10] Gem-like, VS according to the Gemological Institute of America (GIA) scale and method. 2 , VS 1 VVS 2 VVS 1 CVD single crystal diamond according to any one of [1] to [8], having a clarity grade selected from either IF or FL.

[11] H3(NVN 0 ) A CVD single crystal diamond according to any one of [1] to [9], further comprising a center. 〔12〕 In photoluminescence measurements performed at a temperature of 77K using excitation wavelengths of 455 to 459 nm, at least 50 (NV) 0 +NV - A CVD single crystal diamond according to

[10] above, exhibiting a ) / H3 ratio, wherein the NV 0 NV - A CVD single-crystal diamond in which each of the H3 defects is quantified by the ratio of the peak area of ​​the zero-phonon line to the primary Raman signal of the diamond.

[13] Selected from at least 100, at least 150, at least 200, at least 300 and at least 400 (NV 0 +NV - A CVD single crystal diamond as described in [1] above, exhibiting a ) / H3 ratio.

[14] A method for producing multiple single-crystal CVD diamonds as described in any of [1] to

[12] above, Placing multiple single-crystal diamond substrates on a substrate carrier in a chemical vapor deposition reactor; A process gas containing hydrogen-containing gas, carbon-containing gas, and nitrogen-containing gas is supplied to the reactor, wherein the relative amount of the process gas is 1% to 4% C 2 H 2 / H 2 Ratio, and N from 30 ppm to 300 ppm 2 / C 2 H 2 The ratio and the stoichiometrically equivalent of supplying; On at least a portion of the surface of the plurality of single-crystal diamond substrates, the plurality of single-crystal CVD diamonds are grown at a temperature of 750°C to 1000°C; The process involves first annealing at least a portion of the resulting single-crystal CVD diamonds at a temperature of 1500°C to 1800°C; The process involves irradiating the aforementioned multiple single-crystal CVD diamonds to form vacancies in the diamond crystal lattice; The resulting multiple single-crystal CVD diamonds are subjected to a second annealing at a temperature of 700°C to 1100°C, Methods that include...

[15] The relative amount of the process gas is selected from 50 to 200 ppm, 60 to 180 ppm and 70 to 150 ppm. 2 / C 2 H 2 The method according to

[13] above, wherein the ratio is stoichiometrically equivalent.

[16] The relative amount of the process gas is selected from 1 to 3%, 1.5 to 2.5%, and 1.5 to 2%. 2 H 2 / H 2 The method according to

[13] or

[14] above, wherein the ratio is stoichiometrically equivalent.

[17] The method according to any one of

[13] to

[15] , wherein the first annealing is performed at a temperature of 1550°C to 1750°C.

[18] The method according to any one of

[13] to

[16] , wherein the first annealing is performed under diamond stabilization pressure.

[19] The method according to any one of

[13] to

[17] , wherein the irradiation is carried out using electron irradiation of 1 to 10 MeV.

[20] The method according to any one of

[13] to

[16] , wherein the second annealing includes annealing in a temperature range selected from 700 to 1000°C, 800 to 1000°C, and 850 to 950°C.

[21] The method according to any one of

[13] to

[19] , further comprising cutting and polishing at least one of the plurality of single-crystal diamonds to form a gemstone.

[22] The method according to any one of

[13] to

[20] , wherein the growth on the substrate is carried out without interruption as a single CVD synthesis cycle.

[23] The process of growing the plurality of single-crystal CVD diamonds is performed for at least 10 mm 3 / h, at least 20mm 3 / h, at least 30mm 3 / h, at least 40mm 3 / h and at least 50mm 3 The method according to any one of

[13] to

[21] , which provides a volume growth rate for a single-crystal diamond material selected from any of / h.

[24] The method according to any one of

[13] to

[22] , wherein the plurality of CVD single-crystal diamonds are grown at a temperature selected from 800°C to 1000°C; 800°C to 950°C; and 800°C to 900°C.

[25] An apparatus comprising a CVD single crystal diamond as described in any of [1] to

[12] above, the apparatus being selected from an imaging device, a sensing device, a magnetic sensor; a spin resonance device, a quantum information processing device, and a gyroscope device.

Claims

1. below, Single substituted nitrogen atom N in a neutral charge state, as measured by EPR. s 0 The concentration is between 0.25 and 3 ppm; A CVD single crystal diamond having certain properties, Nitrogen vacancy centers (NV) in neutral and negatively charged states 0 and NV - The total concentration of the above N s 0 The concentration is 0.1 to 0.8 times the original concentration. Further including the H3 (NVN 0) center, In a photoluminescence measurement performed at a temperature of 77 K using excitation wavelengths of 455 to 459 nm, at least 50 (NV0 + NV-) / H3 ratios are used, where each of the NV0, NV-, and H3 defects is quantified by the ratio of the peak area of ​​the zero phonon line to the primary Raman signal of the diamond, and (NV0 + NV-) / H3 ratio selected from at least 100, at least 150, at least 200, at least 300 and at least 400, A CVD single-crystal diamond exhibiting one of the following characteristics.

2. A CVD single-crystal diamond according to claim 1, having at least one length dimension of 3.5 mm or more.

3. A hue angle selected from one of the following: -45 to 45°, -10 to 40°, or 10 to 40°. ab A CVD single crystal diamond according to claim 1, having the characteristics described herein.

4. The ratio of SiV to the peak area of the primary Raman signal of diamond in photoluminescence measurements performed at a temperature of 77 K using an excitation wavelength of 660 nm - quantified by the ratio of the total peak area of the zero phonon line and selected from less than 0.5; less than 0.1; less than 0.05; and less than 0.01 of SiV - The CVD single crystal diamond according to claim 1, which exhibits SiV emission.

5. The total volume of the single-crystal CVD diamond material is at least 0.1 mm 2 , at least 1 mm 2 at least 10 mm 2 , at least 20 mm 2 , at least 40 mm 3 at least 60 mm 3 , at least 80 mm 3 and at least 100 mm 3 A CVD single-crystal diamond according to claim 1, selected from any of the following.

6. Gem-like, with a saturation C selected from 5 to 40, 10 to 35, and 15 to 30. * ab A CVD single crystal diamond according to claim 1, having the characteristics described herein.

7. A gem-like CVD single-crystal diamond according to claim 1, having a color grade selected from Fancy Light, Fancy, Fancy Intense, Fancy Vivid, and Fancy Deep, along with one of Pinkish Orange, Orange-Pink, Pink, Purplish Pink, Purple Pink, and Pink Purple, according to the Gemological Institute of America (GIA) scale and method.

8. Gem-like, according to the Gemological Institute of America (GIA) scale and method, VS 2 , VS 1 VVS 2 VVS 1 CVD single-crystal diamond according to claim 1, having a clarity grade selected from either IF or FL.

9. A method for producing a plurality of single-crystal CVD diamonds according to claim 1, Placing multiple single-crystal diamond substrates on a substrate carrier in a chemical vapor deposition reactor; A process gas containing hydrogen-containing gas, carbon-containing gas, and nitrogen-containing gas is supplied to the reactor, wherein the relative amount of the process gas is 1% to 4% C 2 H 2 / H 2 Ratio, and N from 30 ppm to 300 ppm 2 / C 2 H 2 The ratio and the stoichiometrically equivalent of supplying; On at least a portion of the surface of the plurality of single-crystal diamond substrates, the plurality of single-crystal CVD diamonds are grown at a temperature of 750°C to 1000°C; The process involves first annealing at least a portion of the resulting single-crystal CVD diamonds at a temperature of 1500°C to 1800°C; The process involves irradiating the plurality of single-crystal CVD diamonds to form vacancies in the diamond crystal lattice; The resulting multiple single-crystal CVD diamonds are subjected to a second annealing at a temperature of 700°C to 1100°C, Methods that include...

10. The relative amount of the process gas is selected from 50 to 200 ppm, 60 to 180 ppm, and 70 to 150 ppm. 2 / C 2 H 2 The method according to claim 9, wherein the ratio is stoichiometrically equivalent.

11. The relative amount of the process gas is selected from 1 to 3%, 1.5 to 2.5%, and 1.5 to 2%. 2 H 2 / H 2 The method according to claim 9, wherein the ratio is stoichiometrically equivalent.

12. The method according to claim 9, wherein the first annealing is performed at a temperature of 1550°C to 1750°C.

13. The method according to claim 9, wherein the first annealing is performed under diamond stabilization pressure.

14. The method according to claim 9, wherein the irradiation is carried out using electron irradiation of 1 to 10 MeV.

15. The method according to claim 9, wherein the second annealing includes annealing in a temperature range selected from 700 to 1000°C, 800 to 1000°C, and 850 to 950°C.

16. The process of growing the plurality of single-crystal CVD diamonds is performed for at least 10 mm 3 / h, at least 20mm 3 / h, at least 30mm 3 / h, at least 40mm 3 / h and at least 50 mm 3 The method according to claim 9, which provides a volume growth rate for a single-crystal diamond material selected from any of / h.

17. An apparatus comprising a CVD single-crystal diamond as described in claim 1, the apparatus being selected from an imaging device, a sensing device, a magnetic sensor; a spin resonance device, a quantum information processing device, and a gyroscope device.

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