TWI458852B - High colour diamond - Google Patents

Abstract

A method of producing CVD diamond having a high colour, which is suitable for optical applications, for example. The method includes adding a gaseous source comprising a second impurity atom type to counter the detrimental effect on colour caused by the presence in the CVD synthesis atmosphere of a first impurity atom type. The described method applies to the production of both single crystal diamond and polycrystalline diamond.

Description

High color diamond Field of invention

The present invention relates to high chroma CVD diamonds suitable for optical applications, including high chroma grade gemstones. In particular, the present invention relates to a method of adding a gaseous source comprising a second impurity atom type to counteract the deleterious effects on chromaticity caused by the presence of a first impurity atom type in the CVD synthesis atmosphere.

The described method is suitable for the manufacture of single crystal diamonds and polycrystalline diamonds, especially single crystal diamonds.

All documents referred to herein are hereby incorporated by reference.

Background of the invention

Methods for depositing materials such as diamonds onto a substrate by CVD are well established today and have been extensively described in patents and other literature. To deposit a diamond on a substrate, the method generally comprises providing a gas mixture that provides atomic hydrogen or halogen (such as F, Cl) and C or carbonaceous and other reactive species upon dissociation. For example, CH _x , CF _x , where x is 1 to 4. In addition, oxygen-containing sources may be present, and sources for nitrogen or boron may also be present. For example, nitrogen can be introduced into the synthetic plasma in many forms such as N ₂ , NH ₃ , air, and N ₂ H ₄ . In many procedures, inert gases such as helium, neon or argon also occur. Thus, a typical source gas mixture will contain a hydrocarbon C _x H _y , where x and y may each be from 1 to 10, or a halogen hydrogen compound C _x H _y Hal _z , where x and x may each be from 1 to 10 and y can be from 0 to 10, and optionally contains one or more of the following: CO _x , where x can be from 0.5 to 2, O ₂ , H ₂ , N ₂ , NH ₃ , B ₂ H ₆ and an inert gas. Each gas may appear in its natural equipotential ratio, or the relative equipotential ratio may be manually controlled. For example, hydrogen can appear as ruthenium or osmium, and carbon can occur at ^{1 2} C or ^{1 3} C.

Dissociation of the source gas mixture is usually initiated by an energy source such as microwave, RF (radio frequency) energy, a technique based on flame, hot wire or jet, and the resulting reactive gas species are deposited A diamond is formed on a substrate.

Single crystal CVD diamonds have a range of applications, including electronics and highly engineered optics. The nature of the diamond can be tailored to each application, thus limiting the details of the synthesis process and the cost of manufacturing the material. International Patent Publication No. WO 01/96634 describes the synthesis of high purity diamonds suitable for electronic applications, which also exhibit low absorption due to the low impurity levels in the gas phase of the deposition process and subsequently in the solids and are suitable for manufacturing "high" Chroma" diamond (ie, a material that has an absorption close to the theoretical limit of an impurity-free diamond, and therefore generally provides a chromaticity equivalent to the natural diamond color scale of D to better than K, which is the Gem Society of America (GIA) The chroma level on the color scale, see "Diamond Grade ABC", V. Pagel-Theisen, Ninth Edition, 2001, p. 61). However, the degree of control required to provide the low nitrogen levels used in the method of achieving the invention will be costly.

Table 1 shows the American Gemstone (GIA) color ruler, the most widely used and well-known diamond ruler. Table 1 is available from 'Diamond Grade ABC, Handbook', Verena Pagel-Theisen, Ninth Edition 2001, Rubin and Sonn. v., Antoine, Belgium, 61 pages. The chromaticity is determined by comparison with the standard. The chromaticity determination of a diamond is a subjective procedure and can only be reliably performed by those skilled in the art.

Table 2 shows the clarity of the American Gem Society (GIA), the most widely used clearing ruler. Table 2 is available from "Diamond Grade ABC, Handbook", Verena Pagel-Theisen, Ninth Edition 2001, Rubin and Sonn. v., Antoine, Belgium, 61 pages. It takes into account the internal and external flaws on a cut diamond. In general, the type of defect sought is checked by an experienced evaluator with a 10x magnifying glass or an enlarged mirror under appropriate illumination.

By "high-definition clarity" it is meant herein the clarity of at least SI 1, preferably at least VS 2 as defined in Table 2.

The GIA Diamond Gem Rating System is the most widely used rating for diamond gemstones and is generally considered a defining rating. For the purposes of this application, all gem color ratings are based on GIA chroma levels, while other gemstone properties such as clarity are based on the GIA rating system. For a given quality of diamond, that is, a material with known absorption characteristics, the chromaticity of the gem varies with the size and cutting of the gemstone produced, and moves to a poorer chromaticity as the stone becomes larger (toward the letter) The chroma of Z). In order for the chromaticity system to be applied as a material property, it is necessary to further fix the type and size of the gems to be cut. All GIA shade levels provided in this specification are for a standardized 0.5 ct round brilliant cut unless otherwise indicated.

Unlike the development of high purity layers with high chroma, the synthesis of colored gemstones with fine control of impurity levels added to the procedure is described in WO 03/052177 and WO 03/052174. These techniques provide a method for fabricating CVD diamond layers and CVD diamond gems that are typically in the chromaticity range of one of the blue or brown portions of the spectrum.

Nitrogen is a significant impurity in the CVD diamond program. The extent to which it plays a key role in determining the color and quality of materials is emphasized in the prior art mentioned earlier. Nitrogen is very common and forms a large part of the atmosphere and is often a major contributor to gas supply, even if it is designated as “high purity”. The degree required to remove nitrogen from a high purity gas supply to a synthetic high chromal diamond using the method described in WO 01/96634 would be expensive, would affect the cost of the final material, and would require an alternative to more tolerable impurities. A synthetic method suitable for the manufacture of thick layers of high chroma required for the manufacture of gemstones and other selected optical devices.

A diamond containing a single alternative nitrogen form of nitrogen present at a sufficient concentration to provide observable spectrometer characteristics is referred to as a 1b diamond. The spectrum analyzer characteristics include a maximum absorption coefficient at 270 nm, and a gradual decrease in absorption coefficient between approximately 300 nm and 500 nm for longer wavelengths, where a broad absorption band is located at approximately 365 nm. Meter. These characteristics can be seen in the absorption spectrum of a type 1b high pressure high temperature diamond such as spectrum A of Fig. 1. Although a single replacement nitrogen has the greatest effect on the absorption spectrum in ultraviolet light, the weaker absorption in the visible region of the spectrum affects the chromaticity of the type 1b diamond and imparts a characteristic yellow/brown color.

The UV/visible absorption spectrum of a homogeneous epitaxial CVD diamond grown in the presence of nitrogen typically contains one contribution from a single replacement nitrogen having the above spectral characteristics. In addition to a single replacement of nitrogen, homogeneous epitaxial CVD diamonds that grow in the presence of nitrogen typically contain nitrogen in the form of a central portion of the nitrogen vacancy. When the N-V center is electrically neutral [N-V] ⁰ , it results in absorption with a zero phonon at 575 nm. When the N-V center is negatively charged [N-V] ^- , it results in an absorption system with a zero phonon absorption at 637 nm and an associated system with a phonon band at an absorption maximum of approximately 570 nm. . At room temperature, the absorption bands of the two charge states of the N-V center are combined into a broad band from about 500 nm to 640 nm. This absorption band is located in the yellow portion of the visible spectrum, and when it is intense, the crystallization can exhibit a complementary pink/purple color.

The UV/visible spectrum of low-quality homogeneous epitaxial CVD diamonds with nitrogen growth can also appear to gradually increase from the red to blue region of the spectrum and into the measured absorption of ultraviolet light. There may also be contributions from scattering. Except for those associated with single replacement nitrogen, the spectrum generally does not contain other characteristics. This absorption spectrum provides a poor brown color and this diamond often contains clearly visible graphite inclusions.

The absorption spectrum of higher quality homogeneous epitaxial CVD diamonds with the growth of nitrogen contains additional contributions that are not found in natural, HPHT synthetic diamonds or low quality CVD diamonds. It includes centering on two broad bands of approximately 350 nm and 510 nm.

The frequency band located at approximately 350 nm is different from the wide frequency band in the spectral region of the general type 1b and distorts the spectrum of the ordinary type 1b diamond to the extent that it is responsive to a central concentration responsive to a single replacement nitrogen.

Similarly, a band centered at approximately 510 nm can overlap the absorption of the negative nitrogen vacancy center and the visible absorption of the single replacement nitrogen.

The overlap of the various contributions to the absorption spectrum results in a frequency band at approximately 350 and 510 nm resulting in a broad shoulder in the absorption spectrum rather than a significant maximum. However, these contributions to absorption have a very significant effect on the relative absorption coefficient of the diamond at wavelengths in the 400 to 600 nm spectral region where the eye is sensitive to small differences. Therefore, it makes an important contribution to the cognitive color of diamonds.

The width and position in the spectrum of these bands may vary. It is most easy to determine the position of the peak maximum using the second derivative of the spectrum. It has been found that the absorption spectrum of homogeneous epitaxial CVD diamonds in which nitrogen is present and which lacks any second impurities used in accordance with the present invention can generally be decomposed into the following approximate components.

1) a single set of alternative parts of nitrogen, having positioned 0.4 cm summarizes ^{- 1-10} cm ^- an absorption coefficient in the range of ¹ to 270 nm, and summarized located 0.04 cm ^{- 1-1} cm ^{- 1} at 425 nm An absorption coefficient.

2) An absorption band of 3.54 eV (350 nm) +/- 0.2 eV with a FWHM of approximately 1 eV and a maximum contribution of 1 to 8 cm ^{- 1} at the center for the absorption spectrum.

3) An absorption band of 2.43 eV (510 nm) +/- 0.4 eV with a FWHM of approximately 1 eV and a maximum contribution of 0.2 to 4 cm ^{- 1} at the center for the absorption spectrum.

4) A small residual wavelength-dependent component of the wavelength-dependent measured absorption coefficient (in centimeters ^{- 1} ) having the following approximate form: cx (wavelength in micrometers) ^{- 3} , where c < 0.2 at 510 nm so that the contribution of this component is less than 1.5 cm summarized ^--1.

Figure 1 shows the absorption spectrum (curve B) of a brown CVD diamond layer and its components that can be broken down into components. The first step in this spectral decomposition is to subtract the spectrum of the type 1b HPHT synthetic diamond (curve A) in such a way that the residue does not exhibit a 270 nm characteristic. The residue can be decomposed into a spectrum cx λ ^{- 3} two overlapping frequency band component (curve C) and of the type described above (curve D).

It has been found that the ratio of the UV/visible spectrum of CVD diamonds grown using a range of different procedures can be well specified by the sum of the above components, with different weighting factors for the components in different cases. The contributions of the different components are provided in the following manner for the purpose of specifying the shape of the spectrum.

270 nm: The peak 270 nm absorption coefficient of type 1b component is measured from a slope baseline on either side of the Type 1b spectrum used to connect the 270 nm characteristic extending above the approximate range of 235 nm to 325 nm. .

350 nm: The peak absorption coefficient contribution of this band.

510 nm: The peak absorption coefficient contribution of this band.

Slope: contribution of the cx λ ^{- 3} component to the absorbance at 510 nm.

The present invention is a method for producing a CVD diamond layer having a high chroma, comprising: providing a substrate; providing a CVD synthesis atmosphere in which one of the inclusions has a detrimental effect on the chromaticity of the diamond layer produced. a first gas of a first impurity atom type; and a second gas containing a second impurity atom type added to the synthesis atmosphere, wherein the first and second impurity atom types are not the same; The type and number of two impurity atom types to reduce the detrimental effect of the chromaticity caused by the first impurity atom type to thereby produce a diamond layer having a high chroma; and the first and second impurity atom types are independently It is an atom of nitrogen or a solid in the elemental state.

The present invention is also a method for fabricating a CVD diamond layer, comprising: providing a substrate; providing a CVD synthesis atmosphere in which more than 300 ppb of undesired addition of a concentration of nitrogen is present; and a second gas of a second impurity atom type of nitrogen is added to the synthesis atmosphere, wherein the second impurity atom type is added in a controlled manner by a quantity that reduces the detrimental effect on chromaticity caused by nitrogen a high chroma diamond layer; and the second impurity atom type is a solid in the element state.

The invention further relates to a method for making a CVD diamond layer comprising the steps of: providing a substrate; and adding a gaseous source containing helium to a CVD synthesis atmosphere.

The invention is further a CVD diamond layer produced by the method of any of the preceding claims.

The present invention is a CVD diamond layer comprising one of the impurity atom types selected from the group consisting of ruthenium, sulfur or phosphorus, wherein the diamond layer has a high chroma.

The present invention is also one kind of CVD diamond layer wherein the majority volume of the diamond-based layer selected from the group comprising silicon, sulfur or phosphorus from ¹⁰¹⁵ to 2-type impurity atom x 10 ^{1 8} atoms / cubic centimeter.

The invention is also a CVD diamond layer which is manufactured as an optical component according to the method of any one of claims 1 to 33.

The present invention is a CVD diamond layer manufactured according to the method of any one of claims 1 to 33 for use as an electrical or electronic component.

The present invention is also a CVD diamond layer which is produced according to the method of any one of claims 1 to 33 which has a thickness of more than 0.1 mm.

The present invention is also a CVD single crystal diamond layer which is produced in the form of a gemstone according to the method of any one of claims 1, 2, 4 to 22 and 24 to 31.

The invention further relates to a method for producing a sufficient amount of a gaseous source in a method for fabricating a CVD diamond layer having a high chroma, wherein the gaseous source comprises a second impurity atom type to counter a first impurity atom The detrimental effect of type on diamond color.

The invention further relates to a method for using a gaseous source in a CVD diamond manufacturing method, wherein the gaseous source is added to a reaction chamber comprising a substrate and a diamond synthetic atmosphere to make the crucible against a first impurity atom type Harmful effects.

Simple illustration

The invention is described herein with reference to the following drawings in which: Figure 1 shows a spectral decomposition of the UV/visible absorption spectrum of an orange-brown CVD diamond layer, representing a typical CVD diamond layer grown without the application of the method of the invention. . Spectrum A shows a type 1b HPHT synthetic diamond, spectrum B shows an original spectrum of orange-brown CVD diamonds, spectrum C shows a spectral component with (wavelength) ^{- 3} dependence, and spectrum D shows a mixture of two broad absorption bands. Spectral component; Figure 2 shows the photoluminescence spectrum of one of the erbium-doped CVD diamond samples recorded at 77 K by 785 nm laser excitation; and Figure 3 shows the same as described in Example 7. A low magnification optical microscopy image.

Detailed description of the invention

In a first embodiment, the present invention provides a method for fabricating a CVD diamond layer having high chroma, comprising: (i) providing a substrate; (ii) providing a CVD synthesis atmosphere, wherein there is a Generating a first layer of a first impurity atom type having a chromaticity of the diamond layer; and (iii) adding a second gas comprising a second impurity atom type to the synthesis atmosphere, wherein the first and second The types of impurity atoms are not the same; the type and amount of the second impurity atom type are selected to reduce the detrimental effect on the chromaticity caused by the first impurity atom type to produce a diamond layer having a high chroma; and the first and second The impurity atom type is independently nitrogen or an atom which is solid in an elemental state at room temperature and pressure.

In this manner, the method of the present invention is capable of providing a CVD diamond layer having a high chroma, wherein the synthetic atmosphere comprises a gas having a first impurity atom type that will prevent the generation of high chroma diamonds. For example, the presence of a gas in a synthetic atmosphere containing nitrogen will generally result in a yellow/brown synthetic diamond, while the presence of a gas in a synthetic atmosphere containing boron will generally result in a synthetic blue color.

In the present invention, the term "high chroma" is defined in two different ways depending on the form of the diamond material and its application. The definition of "high chroma" as used herein is best suited to the form of the diamond layer produced and its application. When the diamond is in the form of a round brilliant form (i.e., when the diamond is in the form of a gemstone), a GIA ruler is generally used. When a diamond is used in the form of a board for scientific applications, the material summary defines its absorption characteristics. Absorbing features are also used to define polycrystalline diamonds.

Thus, when the diamond layer of the present invention is in the form of a gemstone, the high chroma outline is defined as superior to K on the GIA gem diamond ruler (as described above) as determined for a 0.5 ct round brightness. Chromaticity. This colorimetric level is perceived by the skilled diamond evaluator as being nearly colorless or colorless. The diamond may have a chromaticity better than J, preferably better than I, preferably better than H, preferably better than G, preferably better than F, or preferably better than E. The diamond layer of the present invention has a "very high chroma" in which the chromaticity is determined to be D to F on the GIA gemstone diamond color scale as determined for a 0.5 ct round brilliant pattern.

For technical applications and for the polycrystalline diamond layer of the present invention, the "high chroma" generalization is defined as the majority of the volume of the material at the following specific wavelengths in the near-ultraviolet and visible portions of the electromagnetic spectrum (ie, located approximately 270 奈The wavelength in the range of meters to 800 nm) has at least one of the following absorption coefficients when measured at room temperature: (i) at 270 nm, less than 2.9 cm ^{- 1} , preferably less than 1.9 cm ^{- 1} , preferably less than 1.0 cm ^{- 1,} preferably less than 0.40 cm ^--1; (II) at 350 nm, of less than 1.5 cm ^{- 1,} preferably less than 0.90 cm ^{- 1,} preferably less than 0.50 cm ^{- 1,} preferably less than 0.20 cm ^--1 (iii) at 520 nm, less than 0.45 cm ^{- 1} , preferably less than 0.30 cm ^{- 1} , preferably less than 0.14 cm ^{- 1} , preferably less than 0.06 cm ^{- 1} ; and (iv) at 700 nm, less than 0.18 cm ^{- 1,} preferably less than 0.12 cm ^{- 1,} preferably less than 0.06 cm ^{- 1,} preferably less than 0.03 cm ^--1.

The materials of the present invention may have sharp absorption characteristics in the range of 720 to 750 nm, but they contribute less to chromaticity and are therefore not limited by these definitions.

In order to find the absorption coefficient, the reflection loss must first be subtracted from the measured absorption spectrum. When subtracting the reflection loss, it is important to consider the spectral dependence of the reflection coefficient. This can be determined by the wavelength dependence of the refractive index of the diamond provided by F. Peter at Z. Phys. 15, 358-368 (1923). Using the dependence of the reflection loss of a parallel side plate on the refractive index and the standard formula, the effect of the reflection loss on the apparent absorption rate can be calculated as a function of the wavelength and can be more accurately calculated by subtracting the measured spectrum. Absorption coefficient spectrum.

Alternatively, "high chroma" can be defined using the CIELAB colorimetric system outlined later in this specification. This chroma simulation system is self-absorbing to determine the level of excellence.

As used herein, the term "major volume" means at least 50% of the diamond layer, preferably at least 55%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90%, Preferably at least 95% of the diamond layer.

The second gas is finely added to the CVD diamond synthesis atmosphere. The second gas is preferably added in a controlled manner. The presence of the second gas may be controlled to stabilize the concentration of the second gas to be better than 20%, preferably better than 10%, preferably better than 3%.

Without being bound by any particular theory, the second impurity atom type inhibits the coarsening effect that the first impurity atom type originally had on the growing surface. By keeping the growing surface flat, the ingestion of a defect that would otherwise degrade a wide range of chromaticity is suppressed. Adding a gaseous source containing an impurity atom type (such as nitrogen) to the single crystal CVD diamond synthesis program will change the reaction occurring on the diamond growth surface in such a way that the surface roughness is increased, so that the surface is given The tendency to have defects. This is especially true when an impurity catalyzes a new layer of diamond in a different region of a {100} surface, resulting in a microstep consisting of a terrace with inclined risers for different types of sites containing different defects. The formation is described, for example, by Martineau et al., Gems & Gemology, 40(1), 2 (2004).

There are many types of defects that may potentially be included. For example, a single replacement impurity defect can be incorporated. It contains a carbon atom replaced by an impurity atom. Hydrogen always appears in the CVD growth environment and may become incorporated into itself or with one or more impurity atoms. A vacancy (an unoccupied address in a diamond lattice usually occupied by one carbon atom) may become one or more adjacent impurity atoms (such as nitrogen vacancies) or one or more hydrogen atoms (such as vacancy hydrogen complexes) ()) is incorporated. Partially defective complexes contain impurity atoms, hydrogen atoms, and vacancies (for example, nitrogen vacancy hydrogen complexes). The cluster of vacancies can be formed with or without bound hydrogen and in some cases can be associated with impurity atoms.

It has generally been found that a wide range of defect groups incorporated once the surface is roughened has an adverse effect on the optical and electronic properties of the material. For example, a defect set may contain a portion that would provide poor optical properties to the material because it would, for example, draw light in the visible region of the spectrum. Electronic properties will be degraded because it reduces carrier activity and lifetime.

One of the general mechanisms behind the invention is that a gaseous source containing a first impurity atom type is inhibited by the addition of a second gaseous source containing a second impurity atom type to suppress the first impurity atom type. The detrimental effect of the roughening effect of the growing surface. By suppressing the roughening of the surface, the addition of the second impurity also inhibits the incorporation of a wide range of defects outlined above which degrade the properties of the grown material.

In the case of two impurity atom types, where growth occurs on a flat surface, the two impurity atom types will be summarized in general but have lower efficiency than those observed for growth on a rough surface. However, many of the above-mentioned defects (such as vacancy clusters and hydrogen-related defects) are not observed at all when growth occurs on a flat surface such as the addition of the second impurity atom type. The result is that a moderate concentration of two impurity atom types can be incorporated into the diamond material without having a broad range of defects with the strongest negative effects on the properties of the diamond layer produced, such as its optical transmission.

It is also believed that the method of the present invention may additionally be based on a second general principle in which the two impurity atom types are incorporated in such a way as to compensate each other. For its part, the two impurity atom types are chosen such that within a particular concentration range of the diamond layer, there is no significant adverse effect on the desired material properties. In accordance with the prior teachings in this art, there will be a hypothesis that such an advantage would be excluded from the compensation of the use of nitrogen that would normally be associated with a defect that would degrade one of the chromaticity and other properties. However, in view of the first general principle outlined above, the addition of a second impurity atom type will reduce the defect, the mutual compensation effect between the two impurity atom types will have additional advantages. This is generally due in part to the fact that one impurity atom type compensates for the effect that the other has in its absence and vice versa. Examples of nitrogen and boron can be used to show compensation. Alternative nitrogen and boron provide diamond yellow/brown and blue, respectively, by themselves. However, the inventors of the present application have discovered that when provided together at approximately the same concentration, colorless color defects can be produced because the alternative nitrogen defects donate electrons to the alternative boron defects and the resulting ionized defects do not result in significant optical absorption. material.

For a given set of growth conditions (such as substrate temperature, pressure, and plasma temperature), the inventors have discovered that there is a lower limit that can be tolerated by the CVD diamond synthesis program before the surface is roughened and the grown diamond turns brown. Value nitrogen concentration. However, the low limit nitrogen concentration tends to be low enough to require significant time and expense to avoid the incorporation of defects that would affect the optical and other properties of the material.

The inventors of the present invention have found that the addition of a second impurity atom type (such as boron or ruthenium) to a growing gas will significantly increase the low limit nitrogen concentration to a potential growth environment when relatively little attention is paid to nitrogen elimination. The level of occurrence. This allows diamonds to grow without the presence of relatively high concentrations of nitrogen without degrading the optical and other properties that would otherwise be caused by incorporating defects such as vacancy clusters and hydrogen-related defects. Furthermore, it has been surprisingly found that even though both nitrogen and the second impurity atom type may be significantly incorporated into the grown diamond, this effect may still be present.

It is known in the prior art (WO 2005/061400) to intentionally add a specific dopant to the synthetic atmosphere of a CVD single crystal diamond to provide a "tag" for the single crystal CVD diamond, ie a source or fingerprint. The dopant is selected such that the source or fingerprint is not readily detectable or affects the cognitive quality of the diamond material under normal viewing conditions but can be detected or become specified under specified conditions such as exposure to light or radiation or a specified wavelength. Detectable.

In contrast, the present invention relates to the use of a second impurity atom type to counteract the deleterious effects of chromaticity of one of the first impurity atom types occurring in the CVD synthesis atmosphere. In this manner, the present invention is capable of producing a CVD diamond having a high chroma, even if the CVD synthesis atmosphere contains a first impurity atom type amount which is originally one of diamonds having no high chroma. This has the advantage that by simply adding a particular type and amount of second impurity atoms, no special steps are required to eliminate the type of impurity atoms known to negatively affect the chroma of the diamond from the synthetic atmosphere. Therefore, the synthesis of CVD diamonds can be simplified and more efficient in time and cost.

The CVD diamond layer produced by the method of the present invention can be a single crystal.

Alternatively, the CVD diamond layer can be polycrystalline. Polycrystalline CVD diamonds are known for this skill. It is generalized on a non-diamond substrate (eg, tantalum, tantalum carbide, tungsten, molybdenum, and other carbide forming metals). Combining a growth from a multi-random localization and a directional core in which the growth rate changes with crystallographic orientation results in a particle having a growth direction that is more or less aligned with a single crystallographic direction (eg, parallel to <100> or <110>), but a polycrystalline layer that is randomly oriented perpendicular to the growth direction (ie, in the plane of the layer). This dish is described by those skilled in the art as having a "wire pattern".

Alternatively, the CVD diamond layer can be heteroepitaxial. Heterogeneous epitaxial CVD diamond layers are well known in the art. It is generally grown on single crystal substrates comprising non-diamond materials such as tantalum, tantalum carbide, tantalum niobium and niobium. Complex interstitial structures are often used between the substrate and the CVD diamond layer to control strain and reduce thermal expansion mismatch shocks. The core of the heteroepitary diamond layer is initially formed by a specific orientation relationship with the substrate and subsequently grown into a "domain" of diamonds that are more or less in the same crystallographic orientation, typically for single crystal substrates. One direction presents a certain relationship. The subdomains are usually separated by low angle boundaries. Layers of tens of microns thick have been reported to have a lateral dimension of hundreds of microns.

In the method of the present invention, the first impurity atom type is preferably nitrogen and the second impurity atom type is selected from the group consisting of ruthenium, boron, phosphorus or sulfur. In this way, the addition of a gaseous source system containing atomic types of bismuth, boron, phosphorus or sulfur impurities can counteract the deleterious effects that nitrogen would otherwise have on diamond chromaticity. More preferably, the second impurity atom type is ruthenium and thus the ruthenium impurity atom is resistant to the harmful effects of the nitrogen impurity atom on the diamond. Alternatively, the second impurity atom type is boron and thus the boron impurity atom is resistant to the detrimental effect of the nitrogen impurity atom on the diamond color.

Alternatively, the first impurity atom type is yttrium, boron, phosphorus or sulfur and the second impurity atom type is nitrogen. In this way, the addition of a gaseous source containing nitrogen impurity atoms can counteract the deleterious effects of bismuth, boron, phosphorus or sulfur on the color of the diamond. More preferably, the first impurity atom type is 矽 and thus the nitrogen impurity atom is resistant to the detrimental effect of the erbium impurity atom on the diamond color. Alternatively, the first impurity atom type is boron and thus the nitrogen impurity atom is resistant to the detrimental effect of the boron impurity atom on the diamond color.

If the first or second impurity atom type is nitrogen, the first or second gas may be any gaseous species containing nitrogen such as N ₂ , NH ₃ (ammonia), N ₂ H ₄ ( hydrazine), and HCN (hydrogen cyanide) )Wait. The first or second gas is preferably N ₂ , NH ₃ or N ₂ H ₄ . The first or second gas is preferably N ₂ or NH ₃ , and the first or second gas is preferably N ₂ . The nitrogen present in the synthetic atmosphere is calculated in parts per million (ppm) or parts per billion (ppb) of molecular nitrogen (i.e., N ₂ ) which is the molecular proportion of the total gas volume. Thus, 100 ppb of nitrogen added with molecular nitrogen (N ₂ ) is equivalent to 200 ppb of nitrogen or 200 ppb of ammonia (NH ₃ ).

For the addition of impurities other than nitrogen, the gas phase concentration in ppm or ppb means the concentration in the synthetic atmosphere of the impurities added by the preferred gaseous species.

If the first or second impurity atom type is boron, the first or second gas is preferably B ₂ H ₆ , BCl or BH ₃ . The first or second gas is preferably B ₂ H ₆ .

If the first or second impurity atom type is ruthenium, the first or second gas is preferably SiH ₄ or Si ₂ H ₆ . The first or second gas is preferably SiH ₄ .

If the first or second impurity atom type is phosphorus, the first or second gas is preferably H ₂ S.

If the first or second impurity atom type is phosphorus, the first or second gas is preferably PH ₃ .

For bismuth, boron, sulphur and phosphorus, if a gaseous species other than the preferred species (ie, B ₂ H ₆ , SiH ₄ , H ₂ S, and PH ₃ ) is used to add the impurity atom type to the synthetic environment, the synthesis is determined. The concentration of this species in the environment must take into account the number of atoms of the impurity atom type in the added molecular species.

The impurity atom type is added to the synthetic atmosphere by a gas. Although it is possible to add all impurity atom types with a single element solid, it is not possible or extremely difficult to accurately and reproducibly control the rate at which such additions are made. For example, the addition of boron has been made by exposing solid boron to the synthetic atmosphere; it is also suitable for use in which a solid surface has been used. However, since a gaseous source of an impurity atom type can be prepared in a highly pure form, diluted by a carrier gas gravimetric method, and then post-manufactured to accurately determine the exact concentration, the method of the present invention uses a gaseous atom type of impurity atom. source. Knowing the gas concentration, a gas metering device such as a mass flow controller can be used to add precision and reproducible additions.

The first impurity atom type may be nitrogen and the second impurity atom type may be sulfur. The first impurity atom type may be nitrogen and the second impurity atom type may be phosphorus. The first impurity atom type may be sulfur and the second impurity atom type may be nitrogen. The first impurity atom type may be phosphorus and the second impurity atom type may be nitrogen. The first impurity atom type may be phosphorus and the second impurity atom type may be sulfur. The first impurity atom type may be sulfur and the second impurity atom type may be phosphorus. The first impurity atom type may be boron and the second impurity atom type may be ruthenium. The first impurity atom type may be ruthenium and the second impurity atom type may be boron. The first impurity atom type may be boron and the second impurity atom type may be phosphorus. The first impurity atom type may be phosphorus and the second impurity atom type may be boron. The first impurity atom type may be boron and the second impurity atom type may be sulfur. The first impurity atom type may be sulfur and the second impurity atom type may be boron. The first impurity atom type may be ruthenium and the second impurity atom type may be phosphorus. The first impurity atom type may be phosphorus and the second impurity atom type may be ruthenium. The first impurity atom type may be ruthenium and the second impurity atom type may be sulphur. The first impurity atom type may be sulfur and the second impurity atom type may be ruthenium.

The role of an impurity atom type from the synthetic atmosphere incorporated into a solid diamond is highly dependent on the exact details of the synthesis procedure. These matters have been described in great detail in the prior art and are known to those skilled in the art. The parameters that affect the incorporation level include the nature of the molecular species used to provide the impurity atoms, the temperature of the synthetic atmosphere, the pressure of the synthetic atmosphere, the temperature of the surface of the substrate, the crystallographic nature of the surface, and the gas flow conditions for the synthesis system.

If the first or second gas source comprises nitrogen, the concentration of the nitrogen-containing gas in the synthetic atmosphere may be greater than 300 ppb, greater than 500 ppb, greater than 600 ppb, greater than 1 ppm, greater than 2 ppm, greater than 3 ppm, greater than 5 ppm, greater than 10 Ppm, greater than 20 ppm, greater than 30 ppm. The concentration of the nitrogen-containing gas can range from 300 ppb to 30 ppm, 500 ppb to 20 ppm, 600 ppb to 10 ppm, 1 ppm to 5 ppm, or 2 ppm to 3 ppm.

If the first or second gas source comprises boron, the concentration of the boron-containing gas in the synthetic atmosphere may be greater than 0.5 ppb, greater than 1.0 ppb, greater than 2 ppb, greater than 5 ppb, greater than 10 ppb, greater than 20 ppb, greater than 50 ppb, greater than 0.1. Ppm, greater than 0.2 ppm. The concentration of boron-containing gases in the synthetic atmosphere can range from 0.5 ppb to 0.2 ppm, from 1.0 ppb to 0.1 ppm, from 2 ppb to 50 ppb, and from 10 ppb to 20 ppb. The concentration of the boron-containing gas in the synthetic atmosphere may be less than 1.4 ppm, less than 0.1 ppm, or less than 0.05 ppm.

If the first or second gas source comprises helium, the concentration of helium containing gas in the synthetic atmosphere may be greater than 0.01 ppm, greater than 0.03 ppm, greater than 0.1 ppm, greater than 0.2 ppm, greater than 0.5 ppm, greater than 1 ppm, greater than 2 ppm, greater than 5 Pppm, greater than 10 ppm, greater than 20 ppm. The concentration of helium containing gas in the synthetic atmosphere can range from 0.01 ppm to 20 ppm, 0.03 ppm to 10 ppm, 0.1 ppm to 5 ppm, 0.2 ppm to 2 ppm, or 0.5 ppm to 1 ppm.

Secondary ion mass spectrometry (SIMS) measurements have shown that for a given concentration of germanium in a growing gas, if there is a lack of nitrogen, the concentration of germanium in the growing diamond is greater for {111}, {110}, or {113} growth ratios. 100} grows higher. For the growth of a substrate with {100} orientation, although gaseous helium impurities tend to increase the low limit nitrogen concentration for surface roughening, the addition of high concentration nitrogen to the growing gas will eventually cause surface roughening and enthalpy The efficiency of the entry has increased dramatically. When this occurs, the SIMS measurement indicates that the concentration of germanium in the diamond can significantly exceed the concentration of nitrogen and in these cases the diamond will generally exhibit a high concentration of defects responsible for the spectral properties of the 945 nm in the absorption spectrum (currently One of the grays caused by Xianxin as a neutral vacancy defect. In general, as the concentration of gaseous enthalpy increases, materials that grow on {111}, {110}, or {113} are grayer than earlier for {100} growth.

When silicon is the first or second impurity atom type, the volume concentration of silicon in the majority of the diamond layer may be less than or equal to 2 x 10 ^{1 8} atoms / cc. Most silicon concentration in volume of the diamond layer may be located from ¹⁰¹⁴ atoms / cc to 2 x 10 ^{1 8} atoms / cm ^, from 3 x 10 ^{1 4} atoms / cubic centimeter to ¹⁰¹⁷ atoms / cc , from ¹⁰¹⁵ atoms / cm ^ to 3 x 10 ^{1 6} atoms / cubic centimeter, or from 3 x 10 ^{1 5} atoms / cc to the range of ¹⁰¹⁶ atoms / cc in the. The concentration of radon in most of the diamond layer may be greater than 10 ^{1 3} atoms/cm ^ 3 , greater than 10 ^{1 4} atoms/cm ^ 3 , greater than 3 x 10 ^{1 4} atoms/cm ^ 3 , greater than 10 ^{1 5} atoms / cm ^ 3 , greater than 3 x 10 ^{1 5} atoms / cm ^, greater than ¹⁰¹⁶ atoms / cc, is greater than 3 x 10 ^{1 6} atoms / cm ^, greater than ¹⁰¹⁷ atoms / cc.

When nitrogen is the first or second impurity atom type, the concentration of nitrogen in the volume of the diamond layer is most likely from ¹ x 10 1 ⁴ atoms / cc to 5 x 10 ^{1 7} atoms / cm ^, from 5 x ¹⁰¹⁵ atoms / cc to 2 x 10 ^{1 7} atoms / cubic centimeter, or from ¹ x 10 1 ⁶ atoms / cc to 5 x 10 ^{1 6} atoms / cc. The volume of the nitrogen concentration in the diamond layer may be greater than most 2 x 10 ^{1 5} atoms / cm ^, greater than ⁵ x 10 ¹ 5 atoms / cm ^, greater than ¹⁰¹⁶ atoms / cc, is greater than 3 x 10 ^{1 6} atoms / cubic centimeter, greater than 10 ^{1 7} atoms / cubic centimeter.

When boron is the first or second impurity atom type, the volume of the boron concentration in the diamond layer may be from most ¹⁰¹⁴ atoms / cubic centimeter to ¹⁰¹⁸ atoms / cubic centimeter, from 3 x 10 ^{1 4} atoms /cm ^ 3 to 10 ^{1 7} atoms / cubic centimeter, from 10 ^{1 5} atoms / cubic centimeter to 10 ^{16 6} atoms / cubic centimeter, or from 3 x 10 ^{15 5} atoms / cubic centimeter to 10 ^{16 6} atoms / cubic centimeter. The volume of the boron concentration in the diamond layer may be greater than most ¹⁰¹³ atoms / cc, is greater than ¹⁰¹⁴ atoms / cc, is greater than 3 x 10 ^{1 4} atoms / cm ^, greater than ¹⁰¹⁵ atoms / cc, greater than 3 x 10 ^{1 5} atoms / cm ^, greater than ¹⁰¹⁶ atoms / cc, is greater than 3 x 10 ^{1 6} atoms / cm ^, greater than ¹⁰¹⁷ atoms / cc.

Typically, secondary ion mass spectrometry (SIMS) can be utilized to measure the concentration of the first and second impurity atom types in the diamond layer and the concentration of any other impurities. The detection limit of the impurity atoms varies depending on the SIMS conditions used. However, for the first and second impurity atom types of the present invention, detection limit of SIMS is typically in the range of ¹⁰¹⁴ - ⁷ at ¹ to 10 / cm ^ of the. Certain words, for elements such as boron, silicon and the like, the detection limit is usually about ¹⁰¹⁵ atoms / cm ^, and for nitrogen usually about greater than 3 x 10 ^{1 6} atoms / cc. In some cases, other technologies such as combustion analysis, absorption, EPR can provide higher sensitivity.

When the first and second impurity atom types are nitrogen and silicon, or vice versa when silicon and nitrogen, the nitrogen concentration of the volume of the diamond layer most preferably less than or equal to 2 x 10 ^{1 7} atoms / cc and the diamond the concentration of silicon in the majority volume of the layer is preferably less than or equal to 2 x 10 ^{1 8} atoms / cc. In this way, high chroma in synthetic diamonds can be more easily achieved.

When the first and second impurity atom types are nitrogen and helium, respectively, or vice versa, the concentration ratio of nitrogen to germanium in most of the diamond layer may be 1:20 to 20:1, 1: 10 to 10:1, 1:9 to 9:1, 1:8 to 8:1, 1:7 to 7:1, 1:6 to 6:1, 1:5 to 5:1, 1:4 to 4:1, 1:3 to 3:1, 1:2 to 2:1, preferably 1:1.

When the first and second impurity atom types are nitrogen and helium, respectively, or vice versa, the nitrogen-containing gas may be present in the synthetic atmosphere at a concentration of more than 100 ppb, greater than 200 ppb, and greater than 300 ppb. The gas may appear in the synthetic atmosphere at concentrations greater than 10 ppb.

When the first and second impurity atom types are nitrogen and boron, respectively, or vice versa, the ratio of nitrogen concentration to boron concentration in most of the diamond layer may range from 1:2 to 2:1. 2:3 to 3:2, from 3:4 to 4:3, from 4:5 to 6:5, and from 9:10 to 11:10, and the ratio is preferably 1:1. The ratio of nitrogen to boron is preferably greater than 1:5.

When a single replacement of boron and nitrogen occurs in the diamond at approximately the same concentration, a colorless material can be produced because nitrogen defects donate electrons to boron defects and the resulting ionization defects do not result in significant optical absorption. Thus, not only does boron have a beneficial effect on growth in the presence of nitrogen because it inhibits the growth surface roughening, the boron and nitrogen incorporated into the diamond can compensate each other to provide low optical absorption for the material.

When the first and second impurity atom types are nitrogen and boron, respectively, or vice versa, the nitrogen-containing gas may be present in the synthetic atmosphere at a concentration greater than 100 ppb, preferably greater than 200 ppb, preferably greater than 300 ppb. And the boron-containing gas may appear in the synthetic atmosphere at a concentration greater than 0.5 ppb.

The CVD diamond layer produced by any of the above methods preferably has an increased normalized exciton intensity compared to a method in which the second gas containing the second impurity atom type is not added. It is preferred to have one of the strong free exciton luminescence in the cathodoluminescence spectrum measured at 77 K, wherein the accumulation of free exciton luminescence is more than the accumulation of a homogeneous epitaxial CVD diamond sample grown under high purity conditions. The exciton luminescence intensity is 0.3, preferably more than 0.4, preferably more than 0.5, preferably more than 0.6, preferably more than 0.7, preferably more than 0.8, preferably more than 0.9.

The CVD diamond layer produced by any of the above methods may have an increase in carrier activity, carrier lifetime, charge collection distance, and/or charge collection efficiency as compared to a method in which a second gas comprising a second impurity atom type is not added. The charge collection distance of the resulting diamond layer may be greater than 100 microns, greater than 150 microns, greater than 200 microns, greater than 300 microns, greater than 500 microns, or greater than 1000 microns as measured by an applied electric field of 1.0 volts/micron. A method for measuring the charge collection distance in a diamond is as described in WO 01/96633. The carrier activity of the resulting diamond layer may be 1200 cm ² volts ^{- 1} sec ^{- 1} , preferably 1500 cm ² volts ^{- 1} second ^{- 1} , preferably 1800 cm ² volts ^{- 1} second ^{- 1} , preferably 2200 cm ² volts ^{- 1} second ^{- 1} , preferably 2500 cm ² volts ^{- 1} second ^{- 1} . The charge collection efficiency of the resulting diamond layer is preferably 30%, preferably 50%, preferably 70%, preferably 80%, preferably 90%, preferably 95%, preferably 97%. The carrier lifetime of the resulting diamond layer can be greater than 1 nanosecond, greater than 3 nanoseconds, greater than 10 nanoseconds, greater than 30 nanoseconds, or greater than 100 nanoseconds.

It is known that nitrogen as an impurity affects the electronic properties of single crystal CVD diamonds, particularly charge collection distance, carrier activity, and carrier lifetime. In the absence of nitrogen, the electronic properties of single crystal CVD diamonds will be very good (see, for example, Isberg et al., Science, Vol. 297, pp. 1970-1672, which discloses measurement methods and results). As the nitrogen is gradually added to the synthetic atmosphere, the electronic properties of the resulting material are progressively deteriorated.

Previous experiments have shown that the intensity of the free exciton emission at 235 nm measured at 77 K is a good agent of electronic properties (WO 01/96633). Using this agent, we are able to provide the following expected performance for the combined nitrogen and niobium additions to the diamond.

If hydrazine is added to nitrogen, the harmful effects of nitrogen on the electronic properties are improved, and as the concentration of stront added increases, the amount of modification increases but the rate of improvement decreases until a certain proportion of nitrogen concentration is applied, and further enthalpy is added. There is a further improvement effect at which point the properties will begin to deteriorate again.

Thus, there will be one that is optimal for the addition of a given amount of nitrogen in the solid, but the optimum values will depend on the exact nature of the consideration and the amount of nitrogen incorporated. The inventors expect that the optimum value of the enthalpy additive relative to its effect on the electronic properties is generally less than the enthalpy additive that causes the diamond chromaticity to begin to degrade (i.e., the gradation caused by enthalpy begins to become apparent).

Therefore, a series of diamonds containing a given concentration of nitrogen and different concentrations of germanium (between just above zero and above the optimum) may be slightly better than an otherwise diamond-free diamond. Far better, the same or worse electronic properties.

A diamond of the present invention may likewise have poor electronic properties (i.e., the cerium concentration is stable above the optimum value), but the good optical properties of gradation such as yttrium have not become sufficient to be recognized or optically absorbed by one color change. One of the spectrum changes significantly.

A similar situation relates to the addition of boron to a synthetic atmosphere containing diamonds. Initially, boron improved the harmful effects of nitrogen and improved the electronic properties. As the amount of boron added increases, perhaps when the amounts of nitrogen and boron are approximately equal, the improvement in electronic properties will cease and then begin to decrease by a higher rate of addition. This performance can be understood by a classical semiconductor compensation model. The improvement in properties and the rate of subsequent decline are expected to be far more acute than in the case of nitrogen and helium.

A first gas containing a first impurity atom type may be deliberately added to the synthesis atmosphere. Alternatively, the first gas may unintentionally appear in the synthetic atmosphere, including because it affects the nature of the diamond layer produced but it has not been removed and appears in the synthetic atmosphere. Preferably, the synthetic atmosphere comprises a first gas which has not been intentionally added at a concentration greater than 0.1 ppb, preferably greater than 1 ppb, preferably greater than 10 ppb. An example of this case to tie such NH _3, N ₂ H ₄ or air left in the form of nitrogen in the synthesis atmosphere, and it is considered too expensive or time-consuming and can not adopt additional measures to remove such gases from the synthesis atmosphere. Preferably, the synthetic atmosphere comprises a nitrogen-containing gas having a concentration of greater than 300 ppb that has not been intentionally added.

The first gas may be present in the synthetic atmosphere in a controlled manner or in an uncontrolled manner. If the first gas is present in an uncontrolled manner, the first impurity type atom may be present as an impurity of one of the gases required for diamond synthesis. Alternatively, if the first gas is added in a controlled manner, it may have only an upper limit of the amount of gas that can be introduced into the synthesis atmosphere. Alternatively, the presence of the first gas may be controlled such that the concentration of the first gas is stabilized to be better than 20%, preferably better than 10%, preferably better than 3%.

The diamond layer is preferably greater than 0.1 mm thick, preferably greater than 0.5 mm thick, preferably greater than 1 mm thick, and preferably greater than 2 mm thick.

In the method of the first embodiment: (1) the substrate may be a diamond substrate having a surface substantially free of crystal defects so that a plasma etch will be revealed to be less than 5 x 10 ³ /cm 2 . One of the surface etch characteristic densities associated with the defect; (2) the time course of synthesis of the diamond layer may be at least 50 hours; and/or (3) the substrate may comprise multiple separated single crystal diamond substrates.

The method may comprise at least one, preferably at least two, preferably all three of the characteristics (1) to (3). The method may include characteristics (1), characteristics (2), characteristics (3), characteristics (1) and (2), characteristics (1) and (3), characteristics (2) and (3), and characteristics (1). , (2) and (3).

The use of a diamond substrate having a surface that is substantially free of crystal defects can greatly improve the quality of the diamond being grown. In particular, fewer features will appear in the growing diamond layer.

The substrate may be a single diamond substrate such as in the above 1). Alternatively, the substrate can be a plurality of separate single crystal diamond substrates. The plurality of substrates are preferably laterally separated. Each of the plurality of single crystal diamond substrates may have substantially no crystal defects as described above. A plurality of laterally separated single crystal diamond substrates can be simultaneously grown in the same synthesis system under substantially the same growth conditions.

The method can include the use of a separate multiple single crystal diamond substrate. Preferably, it has greater than 5, greater than 20, greater than 50, greater than 80, greater than 100, greater than 120, greater than 150, and greater than 200 single crystal substrates. The use of such multiple-separated single crystal diamond substrates produces multiple single crystal diamond layers. Alternatively, a polycrystalline diamond layer extending laterally in at least one direction by more than 30 mm, preferably more than 60 mm, preferably more than 90 mm, preferably more than 110 mm, preferably more than 130 mm, may be produced. .

The diamond layer may have a synthetic time course of at least 50 hours, at least 75 hours, at least 100 hours, and at least 150 hours.

In a second embodiment of the present invention, there is provided a method of making a CVD diamond layer comprising: (i) providing a substrate; (ii) providing a CVD synthesis atmosphere in which there is an unintentionally added one of greater than 300 ppb a nitrogen concentration; and (iii) adding a second gas comprising a second impurity atom type other than nitrogen to the synthesis atmosphere,

Wherein the second impurity atom type is added in a controlled manner by a reduced amount of chromogenic effects caused by nitrogen reduction, thereby producing a diamond layer having a high chroma; and the second impurity atom type is in the element state solid.

In this way, even if the synthetic atmosphere is contained in the absence of the second gas, it will have an adverse effect on the chromaticity of the produced diamond so that the produced diamond does not have a high chroma one nitrogen, and a high chroma CVD diamond can be produced. Floor. The method of the second embodiment is capable of synthesizing high chroma CVD diamonds without having to take any additional steps to remove undesirable nitrogen from the synthetic atmosphere. The term "high chroma" is as previously defined. The diamond layer preferably has a very high chroma, as previously defined.

In a second embodiment of the invention, the CVD diamond layer can be a single crystal. Alternatively, in a second embodiment of the invention, the CVD diamond layer may be polycrystalline.

The preferred features of the first embodiment of the method of the invention outlined above are equally applicable to the second embodiment of the method of the invention, as long as the first source gas comprises nitrogen.

In particular, the second impurity atom type may be boron, germanium, phosphorus or sulfur. The second impurity atom type is preferably ruthenium.

In the method of the second embodiment of the present invention, the concentration of nitrogen that is not intentionally added to the synthetic atmosphere can be added in an uncontrolled manner. In addition to the concentration of nitrogen that is not intentionally added to the synthetic atmosphere, additional nitrogen can be deliberately added to the synthetic atmosphere.

In a third embodiment of the invention, a method of producing a CVD diamond layer is provided, comprising the steps of: (i) providing a substrate; and (ii) adding a gaseous source comprising ruthenium to a CVD synthesis atmosphere.

In this way, a tantalum doped diamond layer is provided. Preferably, in the third embodiment of the invention, the CVD diamond layer is a single crystal. Alternatively, in a third embodiment of the invention, the CVD diamond layer is polycrystalline.

In the method of the third embodiment: (1) the layer can be grown to a thickness greater than 0.1 mm; (2) the substrate can be a diamond substrate having a surface substantially free of crystal defects, such that a plasma etching is exposed A surface etch characteristic density of less than 5 x 10 ³ /cm ^ 2 associated with the defect will be revealed; (3) the synthesis time of the single crystal diamond layer can be at least 50 hours; and / or (4) the substrate can be A single crystal diamond substrate comprising multiple separations.

The method may comprise at least one, at least two, at least three, and preferably all four characteristics (1) to (4). The method may include characteristics (1), characteristics (1), characteristics (3), characteristics (4), characteristics (1) and (2), characteristics (1) and (3), characteristics (1) and (4). , characteristics (2) and (3), characteristics (2) and (4), characteristics (3) and (4), characteristics (1), (2) and (3), characteristics (1), (3) and (4), characteristics (2), (3) and (4).

The layer can be grown to a thickness greater than 0.5 mm, greater than 1 mm, and greater than 2 mm.

The synthetic time course of the diamond layer can be at least 50 hours, at least 75 hours, at least 100 hours, at least 150 hours.

The method can include the use of multiple isolated single crystal diamond substrates. It preferably has more than 5, preferably more than 20, preferably more than 50 single crystal substrates. Multiple single crystal diamond layers can be produced using such separate single crystal diamond substrates. Alternatively, a polycrystalline diamond layer extending laterally in at least one direction by more than 30 mm, preferably more than 60 mm, preferably more than 90 mm, preferably more than 110 mm, preferably more than 130 mm, may be produced. .

The preferred features of the first embodiment of the method of the invention outlined above are equally applicable to the third embodiment of the method of the invention, as long as the first or second source gas comprises helium.

Most diamond ¹⁰¹⁴ atomic layer of the third embodiment of the method of the present invention arising / cc to 2 x 10 ^{1 8} atoms / cm ^, from 3 x 10 ^{1 4} atoms / cc to ¹⁰¹⁷ atoms / cubic centimeter, from ¹⁰¹⁵ atoms / cm ^ to 3 x 10 ^{1 6} atoms / cm ^, from 3 x 10 ^{1 5} atoms / cubic centimeter to ¹⁰¹⁶ atoms / cubic centimeter, from 2 x 10 ^{1 7} atoms /cubic centimeters to 2 x 10 ^{1 8} atoms / cubic centimeter.

In a third embodiment of the method of the present invention, the addition of niobium reduces the deleterious effects on the properties of the diamond layer produced due to the presence of an impurity atom type. The impurity atom type is preferably nitrogen. The impurity atom type can be introduced into the synthesis atmosphere as a gas in a controlled or uncontrolled manner, as previously described. The impurity atom type is preferably nitrogen, and the synthetic atmosphere contains an unintentionally added nitrogen concentration of more than 300 ppb.

This property can be chromaticity, and the addition of nitrogen produces a CVD diamond layer with high chroma, where "high chroma" is as defined above. The CVD diamond layer preferably has a very high chroma, wherein "very high chroma" is as defined above.

This property can be a free exciton emission of the diamond layer, while the addition of germanium can result in a CVD diamond layer having an increased normalized exciton intensity compared to a method in which no germanium is added. There may be one strong free exciton luminescence in the cathodoluminescence spectrum measured at 77 K, where the accumulation of free exciton luminescence is more than the accumulation of a homogeneous epitaxial CVD diamond sample grown under high purity conditions. The sub-luminous intensity is 0.3, preferably more than 0.4, preferably more than 0.5, preferably more than 0.6, preferably more than 0.7, preferably more than 0.8, preferably more than 0.9.

The property can be at least one of: carrier activity, carrier lifetime, charge collection distance, and the addition of hydrazine can result in increased carrier activity, carrier lifetime, and/or charge collection compared to a method in which strontium is not added. Distance to the CVD diamond layer. The charge collection distance of the resulting diamond layer may be greater than 100 microns, greater than 150 microns, greater than 200 microns, greater than 300 microns, greater than 500 microns, greater than 1000 microns as measured by an applied electric field of 1.0 volts/micron. The carrier activity of the resulting diamond layer may be 1200 cm ² volts ^{- 1} sec ^{- 1} , preferably 1500 cm ² volts ^{- 1} second ^{- 1} , preferably 1800 cm ² volts ^{- 1} second ^{- 1} , preferably 2200 cm ² volts ^{- 1} second ^{- 1} , preferably 2500 cm ² volts ^{- 1} second ^{- 1} . The charge collection efficiency of the resulting diamond layer is preferably 30%, preferably 50%, preferably 70%, preferably 80%, preferably 90%, preferably 95%, preferably 97%. The carrier lifetime of the resulting diamond layer can be greater than 1 nanosecond, greater than 3 nanoseconds, greater than 10 nanoseconds, greater than 30 nanoseconds, and greater than 100 nanoseconds.

In any of the above methods (i.e., for the first, second, and third embodiments), when the CVD diamond layer is a single crystal, a majority of the volume of the diamond layer can have at least one of the following characteristics: a) at room temperature One of the absorption spectra is measured so that a standard 0.5 ct circular brilliant chromaticity will be better than K; b) an absorption coefficient of less than 1.9 cm ^{- 1} at 270 nm is measured at room temperature; c) measured at room temperature An absorption coefficient of less than 0.90 cm ^{- 1} at 350 nm; d) an absorption of less than 0.30 cm ^{- 1} at 520 nm; or e) an absorption of less than 0.12 cm ^{- 1} at 700 nm.

A majority of the volume of the diamond layer may comprise at least 55%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90%, preferably at least 95% of the diamond layer.

The single crystal diamond layer may have at least two, at least three, at least four, and preferably all five characteristics (a) to (e). The diamond layer may have characteristics a) and b); characteristics a) and c); a) and d); a) and e); b) and c); b) and d); b) and e); And d); c) and e); d) and e); a), b) and c); a), b) and d); a), b) and e); a), c) and d ); a), c) and e); a), d) and e); b), c) and d); b), c) and e); b), d) and e); c), d) and e); a), b), c) and d); a), b), c) and e); a), b), d) and e); a), c), d) And e); b), c), d) and e); or a), b), c), d) and e).

Preferably, for characteristic a), the diamond layer has an absorption spectrum measured at room temperature such that a standard 0.5 ct circular brilliant chromaticity will be better than J, preferably better than I, preferably better than H, Preferably, it is better than G, preferably better than F, preferably better than E, and more preferably D.

Preferably, for characteristic b), the diamond layer has an absorption coefficient of less than 1.0 cm ^{- 1} ; preferably less than 0.4 cm ^{- 1} at room temperature measured at 270 nm.

Preferably, for characteristic c), the diamond layer has an absorption coefficient of less than 0.5 cm ^{- 1} ; preferably less than 0.2 cm ^{- 1} at room temperature measured at 350 nm.

Preferably, for characteristic d), the diamond layer has an absorption coefficient of less than 0.14 cm ^{- 1} ; preferably less than 0.06 cm ^{- 1} at room temperature measured at 520 nm.

Preferably, for the characteristic E), the diamond layer has less than 0.06 cm ^--1; preferably less than 0.03 cm ^--1 measured at room temperature of the absorption coefficient at a 700 nm.

In any of the above methods (i.e., with respect to the first, second, and third embodiments), when the CVD layer is polycrystalline, a majority of the volume of the diamond layer can have at least one of the following characteristics: a) less than 1.9 cm. ^--1 measured at room temperature in the 270 nm absorption coefficient a; b) is less than 0.90 cm ^--1 measured at room temperature in the 350 nm absorption coefficient a; c) is less than 0.30 cm ^--1 at 520 nm of an absorbent; and d) less than 0.12 cm ^--1 of absorption in a 700 nm.

The polycrystalline diamond layer may have characteristics a), properties b), properties c), properties d), properties a) and b), properties a) and c), properties a) and d), properties b) and c), Characteristics b) and d), characteristics c) and d), characteristics a), b) and c), characteristics a), b) and d), characteristics a), c) and d), characteristics b), c) And d), or characteristics a), b), c) and d).

Preferably, for characteristic a), the diamond layer has an absorption coefficient of less than 1.0 cm ^{- 1} ; preferably less than 0.4 cm ^{- 1} at room temperature measured at 270 nm.

Preferably, for characteristic b), the diamond layer has an absorption coefficient of less than 0.5 cm ^{- 1} ; preferably less than 0.2 cm ^{- 1} at room temperature measured at 350 nm.

Preferably, for characteristic c), the diamond layer has an absorption coefficient of less than 0.14 cm ^{- 1} ; preferably less than 0.06 cm ^{- 1} at room temperature measured at 520 nm.

Preferably, for the characteristics d), the diamond layer has less than 0.06 cm ^--1; preferably less than 0.03 cm ^--1 measured at room temperature of the absorption coefficient at a 700 nm.

In any of the above methods wherein CVD is a single crystal, the diamond layer is preferably formed into a gemstone having three orthogonal dimensions greater than 2 mm, wherein at least one axis is disposed along the <100> crystallographic direction or along The main axis of symmetry of the gemstone.

According to the present invention, there is provided a CVD diamond layer produced by any of the methods disclosed above.

If the CVD layer is a single crystal, most of the volume of the diamond layer can be formed from a single growth section.

In view of the reduced defects in the diamond layer produced by any of the above methods of the present invention due to reduced surface roughening during growth, the diamond layer may also have improved mechanical and chemical properties, including abrasion resistance and thermal stability. The wear properties of a material are the result of a very complex interaction between a broad range of material macroscopic properties, including, for example, hardness, strength, stiffness, toughness, particle size, thermal conductivity, particle orientation, and the like. Diamonds are known in the art to have excellent attrition properties and are widely used: they are used in a wide range of applications including cutting tools, rock drills, wire dies, and many other applications. As a tool material.

The effectiveness of diamond tools in specific applications is strongly influenced by their microstructure and is affected by point and extended defect densities in the case of specific single crystal diamonds. A specific example is a wire drawing die as disclosed in WO 2004/074557, wherein it is shown that reducing the strain system by controlling the elongation defect density is particularly effective for improving the wear properties. Since the method of the present invention provides reduced dots and extended defect densities for single crystal diamond materials as compared to diamonds prepared using the same general method but without the addition of a second impurity, it is reasonable to expect that the materials of the present invention will have Improved wear properties.

According to the present invention, there is also provided a CVD diamond layer comprising one of the impurity atom types selected from the group consisting of ruthenium, sulfur or phosphorus, wherein the diamond layer has a high chroma.

According to the present invention, there is provided a CVD diamond layer comprising an impurity atom type selected from the group consisting of ruthenium, sulfur or phosphorus, wherein the concentration of impurity atom types in a majority of the volume of the diamond layer is from 10 ^{1 4} to 2 x 10 ^{1 8} atoms / cubic centimeter. Most of the volume concentration of the silicon-based diamond layer may be greater than ¹⁰¹³ atoms / cc, is greater than ¹⁰¹⁴ atoms / cc, is greater than 3 x 10 ^{1 4} atoms / cm ^, greater than ¹⁰¹⁵ atoms / cc , greater than 3 x 10 ^{1 5} atoms / cm ^, greater than ¹⁰¹⁶ atoms / cc, is greater than 3 x 10 ^{1 6} atoms / cm ^, greater than ¹⁰¹⁷ atoms / cc. The concentration of impurity atom type may be from 3 x 10 ^{1 4} atoms / cubic centimeter to ¹⁰¹⁷ atoms / cubic centimeter, from ¹⁰¹⁵ atoms / cm ^ to 3 x 10 ^{1 6} atoms / cubic centimeter, or from 3 x 10 ¹⁵ atoms / cubic centimeter to ¹⁰¹⁶ atoms / cubic centimeter, from ¹⁰¹⁶ atoms / cc to 2 x 10 ^{1 7} atoms / cm ^, from 2 X ¹⁰¹⁶ atoms / cubic centimeter to ¹⁰¹⁷ atoms / cc, is greater than 2 x 10 ^{1 7} atoms / cc. Most preferred volume-based CVD diamond layer comprises from 2X10 ^{1 7} atoms / cm ^ to impurity atom type selected from silicon, sulfur or phosphorus 2 x 10 ^{1 8} atoms / cm ^ of. The impurity atom type is preferably ruthenium. The CVD diamond layer can be a single crystal. Alternatively, the CVD diamond layer can be polycrystalline.

Photoluminescence spectroscopy provides a sensitive method for detecting the presence of defects associated with defects in diamonds. A 737 nm of a related photoluminescent line can generally be detected by a 77K 633 nm HeNe laser excitation. Studies by the inventors have indicated that the photoluminescence spectrum of ytterbium doped diamond excited by 785 nm laser radiation at 77 K also often shows a line of 946 nm. This is usually accompanied by another line of 975 nm. The two photoluminescent lines have not been reported before. Figure 2 shows a typical photoluminescence spectrum for a warp-doped diamond excited by 785 nm of laser radiation.

The present invention has also utilized EPR (Electron Ultra Magnetic Resonance) to investigate warp-doped samples. This provides a sensitive method for detecting and characterizing defects associated with defects. Current detection limits allow measurement of defect concentrations as low as one ppb. EPR has recently been utilized to detect and characterize a neutral vacancy defect, and work continues to identify other 矽 related defects in the same manner. The current results suggest that the 946 nm photoluminescence line may be an optical signature that utilizes the EPR to identify the neutral vacancy defect.

The CVD diamond layer preferably has a high chroma, wherein "high chroma" is as defined above.

The CVD diamond layer preferably has a thickness greater than 0.1 mm, preferably greater than 0.5 mm, preferably greater than 1 mm, preferably greater than 2 mm.

The CVD diamond layer produced by any of the methods of the present invention may be greater than 0.1 cubic centimeters, preferably greater than 0.5 cubic centimeters, preferably greater than 1 cubic centimeter, preferably greater than 3.4 cubic centimeters, and more preferably greater than 8 cubic centimeters. Preferably, it is greater than 27 cubic centimeters, preferably greater than 64 cubic centimeters, preferably greater than 125 cubic centimeters, preferably greater than 512 cubic millimeters, preferably greater than 1000 cubic millimeters, and one volume above one x 10- ^3, preferably less than 1 x 10 ^{- 4,} preferably less than 3 x 10 ^{- 4,} preferably less than 1 x 10 ^{- 5} of the birefringence. Available, such as Metripol Equipped to characterize birefringence.

For a directional medium such as a stress-free diamond, the refractive index is independent of the direction of polarization of the light. If a diamond sample is stressed in a heterogeneous manner, the refractive index will be anisotropic due to growth stress or local defects or due to externally applied pressure. The refractive index variation for the polarization direction can be represented by a surface having one of the general forms of an ellipsoid called optical indicatrix. The difference between the axes of any two ellipsoids is the linear birefringence of the light guided along the third. This can be expressed as a function of the refractive index, stress, and photo-elastic coefficient of the unstressed material.

Metripol (Oxford Cryosystems) provides information on how the refractive index of a given wavelength depends on the direction of polarization in a plane perpendicular to the viewing direction. Metripol For a description of how this works, see AMGlazer et al., Proc. R. Soc. Lond. A (1996) 452, 2751-2765.

Metripol The instrument determines the direction of the "slow axis", that is, the direction of polarization in a plane perpendicular to the viewing direction that maximizes the refractive index. Also measured | sinδ |, where δ is the phase shift provided by: δ = (2π / λ) Δn L

Where λ is the wavelength of light, L is the thickness of the sample, and Δn is the difference between the refractive indices of light polarized parallel to the slow and fast axis (ie, birefringence). Δn L is known as "optical block".

For the first-order block, where L = 0.6 mm and λ = 589.6 nm, then: when sin δ = 1 and Δn L = λ / 4, Δn = 2.45 x 10 ^{- 4} can be inferred.

When sin δ = 0.5 and Δn L = λ / 12, Δn = 0.819 x 10 ^{- 4} can be inferred.

Metripol A three color code image is produced which shows a) the spatial variability of the "slow axis", b) | sin δ | and c) the absorbance of the operating wavelength.

The samples were prepared from optical plates of known thickness and analyzed on an area of at least 1.3 mm x 1.3 mm, preferably 2.5 mm x 2.5 mm, more preferably 4 mm x 4 mm. Metripol The sinδ | image is then analyzed and the maximum value of | sin δ | in each frame above the overall analysis area can be calculated for the overall analyzed area and these values used to characterize the maximum value of Δn.

The sinusoidal δ is expressed as a property of a particular material sheet, and is limited to a plate of effective thickness by applying a minimum thickness. △ difference between the information may be converted by a sinusoidal δ back above the average thickness of the sample parallel to the polarization of light for the slow and fast axes of the refractive index n _{[average level]} values one obtains a more basic properties of the material .

Instrument resolution and noise system for | sinδ | values and therefore for Metripol The measured retardation Delta-nd sets a lower limit. This in turn sets a lower limit on the measurable birefringence, but the limit of this parameter depends on the thickness of the sample. Used for demonstration, if | sin delta | lower limit is 0.03, for light of 550 nm wavelength, which corresponds to a 500 micron thickness △ samples of n = 1.05x10 ^{- 5} measurable lower limit of a birefringent; or a 3500 △ thickness of the sample of m n = 7.5x10 ^{- 7} measurable lower limit of a birefringent.

The birefringence value can be determined in three orthogonal directions that are substantially capable of volume measurement. This may be particularly important in some applications such as spherical optics. The limits defined below are calculated on a measurement basis and assuming a 3 mm path length.

Preferably, the method of the present invention provides for the manufacture of a diamond material such that the birefringence measurement exhibits a value of Δn in at least one, preferably two, preferably all three orthogonal directions such that: Δn is preferably greater than 1x1 Above the aliquot, preferably above 2x2 mm, preferably above 4x4 mm, preferably above 7x7 mm, preferably above 15x15 mm, less than 2x10 ^{- 6} ; Δn is better 1x1 mm larger than the above area, preferably greater than 2x2 mm in the upper region, preferably greater than 4x4 mm in the upper region, preferably greater than 7x7 mm in the upper region, preferably greater than 15x15 mm upper region is smaller than 5x10 ^{- 6;} △ n in the preferred system is greater than the upper region of 1x1 mm, preferably greater than 2x2 mm in the upper region, preferably greater than 4x4 mm in the upper region, preferably greater than 7x7 mm in the upper region, preferably greater than 15x15 mm upper area is less than 1x10 ^{- 5} .

If the birefringence value is below a given low limit for each of the three orthogonal directions of a particular diamond volume, then for the purposes of this specification, the volume is considered to have a birefringence below the lower limit. Value.

The invention also provides for the use of a CVD diamond layer as an optical component in accordance with any of the methods outlined above.

The invention also provides for the use of a CVD diamond layer as an electrical or electronic component in accordance with any of the methods outlined above. The invention also provides a CVD diamond layer produced by any of the above methods for use as a cutting tool or wire drawing die or other anti-wear element.

The invention also provides a CVD diamond layer produced according to any of the methods outlined above, wherein the diamond layer has a thickness greater than 0.1 mm, preferably greater than 0.5 mm, preferably greater than 1 mm, preferably greater than 2 mm. a thickness.

The invention also provides a CVD single crystal diamond layer produced according to any of the methods outlined above, wherein the diamond layer is in the form of a gemstone.

The CVD single crystal diamond preferably has three orthogonal dimensions greater than 2 mm, wherein at least one of the axes is configured along the <100> crystal direction or along the major axis of symmetry of the gemstone. The three orthogonal dimensions are preferably greater than 2.5 mm, preferably greater than 3.0 mm, and more preferably greater than 3.5 mm. The CVD single crystal diamond preferably has a high definition clarity and at least SI1 clarity on the GIA gemstone scale, as defined above. The CVD single crystal diamond layer preferably has a clarity of at least VS2, preferably at least VVS2, preferably at least VVS1, on the GIA gemstone scale.

The method of the present invention can be used to make CVD polycrystalline diamonds in which the deleterious effects of, for example, nitrogen can be improved. In particular, it can counteract the detrimental effects of having a small amount of nitrogen on the electrical properties of polycrystalline diamonds, such as charge collection efficiency and carrier lifetime. In this way, because of the improvement in electrical properties, a polycrystalline diamond containing nitrogen can be used as a detector. This has the advantage of enabling the detector to be made of nitrogen-containing polycrystalline diamonds rather than relying on "pure" polycrystalline diamonds that are far more expensive than synthetic.

The polycrystalline CVD diamonds produced by the method of the present invention can be used as a material having low optical absorption in the far infrared portion of the electromagnetic spectrum (which is used to fabricate long-wave infrared optical components including imaging domes for laser exit windows and missiles, And other uses). Components that are more efficient than currently possible can be fabricated using the method of the present invention.

The polycrystalline diamond produced by the method of the present invention can also be used as a material having a low dielectric loss in the microwave portion of the electromagnetic spectrum (which is used in the exit window of a high-powered gyrotron) and as a material in which heat conduction is highly valued. (used in thermal management applications).

The diamond layer produced by any of the methods of the present invention preferably has a high crystalline quality. In the case of single crystal diamonds, "high crystalline quality" may allow the presence of impurity atoms and associated point defects but may be limited for the presence of differential beams or other extended defects that may affect the use of the material in optical applications, such as causing excessive scattering. , or the chromaticity, or intensity or handleability, is reduced below what is required for the intended optical application. In the case of polycrystalline diamonds, "high crystalline quality" refers to materials having a negligible amount of non-diamond carbon and other defects in the grain boundaries. These defects have a significant impact on the workability of the material in optical and other applications and are therefore undesirable.

The present invention also provides for the use of a sufficient amount of a gaseous source containing a second impurity atom type to counteract a deleterious effect on the chromaticity of a first impurity atom type in a method for fabricating a CVD diamond layer having a high chroma. High chroma is as defined above. Preferred properties relating to the gaseous source and the first and second impurity atom types as defined in the first, second and third embodiments of the method of the invention are equally applicable to this use.

The present invention also provides for the use of a gaseous source of ruthenium to add to a reaction chamber comprising a substrate and a diamond synthetic atmosphere such that the ruthenium adversely affects the first impurity atom type in a CVD diamond manufacturing process. The preferred characteristics of the gaseous source, hydrazine and first impurity atom type as defined in the second embodiment of the method of the invention are equally applicable to this use.

In all methods, diamond layers and uses provided by the present invention, additional impurities may be present in the diamond layer produced. The total concentration of any additional impurities (excluding hydrogen) is less than 5 ppm, preferably less than 2 ppm, preferably less than 1 ppm, preferably less than 0.5 ppm, preferably less than 0.2 ppm. The concentration of any single crystal additional impurities (excluding hydrogen) in the diamond layer is 2 ppm or less, preferably 1 ppm or less, preferably 0.5 ppm or less, preferably 0.2 ppm or less, preferably 0.1. Ppm or less.

In accordance with the present invention, a method for making a "high chroma", low optical absorption single crystal CVD diamond as defined above includes providing a diamond substrate providing a level of one or more gaseous impurities comprising or exhibiting significant The source gas, the source gas is dissociated to produce a synthetic atmosphere containing a significant level of one or more gaseous impurities, and the step of allowing the homogeneous epitaxial diamond on the diamond substrate to grow.

By "low optical absorption" is meant a material that absorbs little in the visible spectrum. In particular, a diamond layer has low optical absorption if at least 50% of the diamond layer (most of the volume) has an absorption coefficient of less than 20 cm ^{- 1} at all wavelengths between 300 and 1000 microns. A diamond layer having low optical absorption may have an absorption coefficient of less than 2 cm ^{- 1} at 270 nm, and/or an absorption coefficient of less than 1.5 cm ^{- 1} at 350 nm, and/or less than 1 cm at 520 nm. ^{- 1} absorption coefficient. All absorption coefficients were measured at room temperature.

The gaseous impurities (as defined below) are preferably selected from the group consisting of N, B, Si, P and S, and particularly preferably at least N.

In a preferred embodiment of the invention, the level of the first gaseous impurity, and particularly the nitrogen, is not optimal for high chroma, low optical absorption CVD diamond materials that are capable of producing the present invention alone. In this embodiment of the invention, at least to the extent that the upper limit is not exceeded, the level of the first gaseous impurity in the synthetic atmosphere may be stabilized or determined, and a second gaseous impurity is introduced into the synthetic atmosphere in a controlled manner. The second impurity is selected and provided in an appropriate amount to reduce the effect on the chromaticity of the first impurity.

The second gaseous impurity is preferably selected from the group consisting of N, B, Si, S, and P.

The single crystal CVD diamond material of the present invention, in addition to being grown in a synthetic atmosphere having significant gaseous impurity levels, may itself include significant impurity levels while maintaining the desired high chroma and low optical absorption characteristics.

In particular, the single crystal CVD diamond material of the present invention preferably contains one or more of the significant levels of impurities N, B or Si, and in particular at least N.

The single crystal CVD diamond material of the present invention preferably also has a high definition clarity, particularly as defined herein.

Preferably, the CVD diamond material is grown on the surface of a diamond substrate that is substantially free of crystal defects.

The invention extends to high chroma, low optical absorption, and preferably high definition, single crystal CVD diamonds containing significant impurity levels in the crystalline structure.

The single crystal CVD diamond of the present invention is suitable for use in optical applications such as diamond windows, diamond lenses and drills, and is used to shape a gemstone, particularly a high chroma grade gemstone.

The application of the CVD diamond produced by the method of the present invention includes optical applications such as infrared transmission windows, etalons for which stress control and birefringence are to be minimized, blades, electrons such as Schottky diodes Components, and radiation detectors.

The above described method of the present invention is useful for the manufacture of high chroma, low optical absorption single crystal CVD diamonds suitable for optical and gemstone applications. The above described method of the invention is also useful for the manufacture of high chroma, low optical absorption polycrystalline CVD diamonds. The CVD procedure is carried out in a synthetic atmosphere containing one or more gaseous impurities of significant level and in particular a gaseous impurity in which nitrogen gas is present. High-color, low optical absorption single crystal CVD diamonds are suitable for use in optical and gemstone applications, although or in certain cases because of one or more impurities that contain significant levels and such impurities include nitrogen, helium, and boron. The particular properties of diamonds that are often considered to be present in a high quality, high purity CVD diamond in a particular form or to a particular extent are also modified or incorporated into the diamond by the presence of impurities in the growth process, and the invention is further These modified high chroma diamond materials.

A particular example is the addition of niobium to a nitrogen-containing CVD diamond synthesis atmosphere, which has been shown to increase the normalized FE intensity, and thus is expected to significantly improve other electronic properties toward values already measured in the absence of nitrogen. . In addition, the reduction in defects in diamonds due to reduced surface roughening during growth is expected to improve several other mechanical and chemical properties, including abrasion resistance and thermal stability. It is expected that the thermal stability will be improved particularly in the case where it is possible to have a stabilizing pressure, such as during annealing.

The diamond material of the present invention may advantageously have "high chroma" and "low optical absorption" as defined above.

High chroma diamonds can be characterized in several ways. The preferred and most defined way for a material used in a gemstone application is to prepare a gemstone from the material and characterize the color of the gemstone. In particular, the present invention can be used to manufacture a material of a number and size of a 0.5 ct CVD diamond gemstone that will form a round brilliant shape, which has a better than K, better than J, better than I, and more Better than H, better than G, better than F, best better than E, the natural diamond color ruler is based on one color. By "better" in this context is meant one of the higher chroma or lower absorption side, ie towards the side with the D color stone body, in the case of better than the E color, the D color or complete Colorless diamonds.

Throughout this application, the chromaticity of a diamond refers to the GIA color scale, as described above. The GIA ruler passes from D to Z, and the higher letters. The "high chroma" convention is the range of chromaticities from D to better than K at the lower end of the letter. The GIA ruler system is widely used in the global diamond industry [see "Diamond Ratings ABC", V. Pagel-Theisen, 9th Edition, 2001, pages 61 and 64-83, how to determine the chromaticity description]. Basically, the chroma level is determined by comparing the diamonds against the diamond standard of the previously determined chroma. The use of “colorless” to describe diamond chromaticity seems to be abnormal, but “colorless” refers to undetected or slightly assisted human eye detection low limits: optical instruments such as spectrometers are capable of detecting far below them. The absorption of color in a diamond that is recognized by the human eye as a color. Therefore, it would be perfectly reasonable to treat the human eye as a colorless diamond as having a position on a color ruler.

Since a larger gemstone has a lower chromaticity level for the same optical absorption coefficient, a specific size of the gemstone is required in this chromaticity definition to properly identify the chromaticity of a diamond material. However, it is understood that this reference to a gem size does not limit the invention to any particular size or cut gemstone. If the material is in the form of a different size and/or cut gemstone, or cannot be made in a gemstone form, and a better round brilliant cut gemstone, the chromaticity calculation of the uniform round brilliant cut chroma is provided here. The appropriate method.

For other optical applications, the key parameters are generally the optical absorption coefficients across the relevant optical range in the application. In particular, the absorption coefficients of diamonds with wavelengths of 270 nm, 350 nm, and 500 nm are specific coherence, resulting from defects caused by common impurities under normal processing conditions, and often play a role in material color or absorption. A significant role may limit its use. Accordingly, the CVD diamond material of the present invention described above will preferably have one, preferably two, and most preferably the following features that can be observed in the optical absorption spectrum: (i), (ii), (iii), (iv) : i) all wavelengths between 300 to 1000 nm in one of the absorption coefficient measured at room temperature, which is smaller than 2 cm ^{- 1,} more preferably less than 1 cm ^{- 1,} more preferably less than 0.5 cm ^{- 1,} and most preferably less than 0.2 cm ^{- 1} ; ii) one absorption coefficient of 270 nm, which is less than 2 cm ^{- 1} , more preferably less than 1 cm ^{- 1} , more preferably less than 0.5 cm ^{- 1} , and most preferably less than 0.2 cm ^{- 1} ; iii) 350 one nm absorption coefficient, which is smaller than 1.5 cm ^{- 1,} more preferably less than 0.75 cm ^{- 1,} more preferably less than 0.3 cm ^{- 1,} and most preferably less than 0.15 cm ^--1; IV) one of the absorption coefficient 520 nm, which Less than 1 cm ^{- 1} , more preferably less than 0.5 cm ^{- 1} , more preferably less than 0.2 cm ^{- 1} , and most preferably less than 0.1 cm ^{- 1} .

The CVD diamond material of the present invention described above will preferably have one, more preferably two, more preferably three, more preferably four, and most preferably the following features (1) that can be observed in most of the volume of the layer, (2), (3), (4), (5), wherein a majority of the volume comprises at least 50%, preferably at least 55%, preferably at least 60%, preferably at least 70%, preferably at least 80% Preferably, at least 90% and optimally at least 95% of the overall volume of the layer: 1) less than 150 microns, preferably less than 100 microns, more preferably less than 50 microns, more preferably less than 20 microns, more preferably less than 10 microns, and Optimal charge collection distance of less than 5 microns, all charge collection distances are measured at an applied field of 1 volt/micron and measured at 300K. Or a charge collection distance greater than 100 microns, preferably greater than 150 microns, preferably greater than 200 microns, preferably greater than 300 microns, preferably greater than 500 microns, and preferably greater than 1000 microns (although most applications may benefit from A high charge collection distance requires that some applications of very high speed detectors benefit from low charge collection distances, especially high crystal quality that can be achieved with a preferred method of the invention; 2) greater than 0.05 ppm, more One of at least one impurity (excluding hydrogen) preferably greater than 0.1 ppm, more preferably greater than 0.2 ppm, more preferably greater than 0.5 ppm, more preferably greater than 1 ppm, still more preferably greater than 2 ppm, more preferably greater than 5 ppm, and most preferably greater than 10 ppm The level (impurity concentration can be measured, for example, by secondary ion mass spectrometry (SIMS), glow discharge mass spectrometry (GDMS) or combustion mass spectrometry (CMS), electronic ultra-magnetic resonance (EPR), and IR (infrared) absorption). In addition, uncompensated single-substitute nitrogen concentrations (calibrated against standard values obtained from destructively analyzed samples from combustion analysis) can be determined from baseline peaks at 270 nm after baseline subtraction; 3) greater than 0.2 ppm, more preferably more than 0.5 ppm, more preferably more than 1 ppm, more preferably more than 2 ppm, more preferably more than 5 ppm, more preferably more than 10 ppm, more preferably more than 20 ppm, one total impurity concentration (excluding hydrogen) (impurity concentration) Can be measured as above); 4.1) weak free exciton luminescence in the cathodoluminescence spectrum measured at 77 K, wherein the accumulation of free exciton luminescence is preferably not more than 0.5, more preferably not more than 0.2, more preferably not more than 0.1. Preferably, no more than 0.05 is a free exciton luminescence intensity accumulated for a homogeneous epitaxial CVD diamond sample grown under high purity conditions (as disclosed by WO 01/96634). Alternatively, one of the cathode luminescence spectra measured at 77K is strongly free exciton luminescence, wherein the intensity of accumulation of free exciton luminescence is preferably more than 0.5, preferably more than 0.6, preferably more than 0.7, preferably more than 0.8, preferably. Excessive exciton luminescence intensity over 0.9 for a homogeneous epitaxial CVD diamond sample grown under high purity conditions; or 4.2) free radical excitation by a 193 nm ArF excimer laser at room temperature The intensity of the sub-emission is such that the quantum productivity for free exciton emission is less than 10 ^{- 4} , more preferably less than 10 ^{- 5} , and even more preferably less than 10 ^{- 6} . Alternatively, the free exciton emission is greater than 10 ^{- 6} , preferably greater than 10 ^{- 5} , preferably greater than 10 ^{- 4} . The free exciton emission can also be excited by the above-described bandgap radiation, such as by 193 nm radiation from an ArF excimer laser. The appearance of strong free exciton emission in the photoluminescence spectrum excited by this method indicates that there is substantially no difference in emissions and impurities; 5) in EPR, more than 1 x 10 ^{16 6} centimeters ^{- 3} at g = 2.0028, More preferably more than 2 x 10 ^{1 6} atomic centimeters ^{- 3} , more preferably more than 5 x 10 ^{1 6} atomic centimeters ^{- 3} , more preferably more than 1 x 10 ^{1 7} atomic centimeters ^{- 3} , more preferably more than 2 x 10 ^{1 7} atomic centimeters ^{- 3} , optimally more than 5 x 10 ^{1 7} atomic centimeters ^{- 3} one spin density. Alternatively, the spin density is preferably less than 5 x 10 ^{1 7} atoms cm ^{- 3} and preferably less than 2 x 10 ^{1 7} atoms cm ^{- 3} and preferably less than ¹ x 10 1 ⁷ atoms cm ^{- 3} and preferably less than 5 x 10 ^{1 6} atomic centimeters ^{- 3} , preferably less than 2 x 10 ^{1 6} atomic centimeters ^{- 3} , preferably less than 1 x 10 ^{1 6} atomic centimeters ^{- 3} (in single crystal diamonds, this line is related to lattice defect concentration and is usually poor The quality of the homogeneous epitaxial diamond is large but is small in high chroma CVD diamonds using a high purity growth procedure).

Most of the volume of the layer is preferably formed from a single growth section.

A key aspect of the above described invention is that growth occurs in a CVD reactor using a gas mixture containing at least one gaseous impurity, more preferably at least two gaseous impurities. Preferably, the method of the present invention resides in wherein at least one gaseous impurity is at least partially produced without intentional addition, but because of the difficulty or cost of further reducing its level by treating the source gas or modifying the vacuum environment, Deliberately adding a second impurity or a procedure available to improve the effect of the first impurity. In this specification, a gaseous impurity is any element other than carbon, and its normal elemental state at room temperature and pressure is solid but can be taken in gaseous form and can be added, or otherwise treated as a gas in a gas mixture. Occurs, or may be transferred within the program via a gaseous form such as from the wall of the reactor or from other solid elements within the reactor volume, where the element may (i) be incorporated into the diamond lattice, or (ii) The diamond's growth surface interacts and modifies the quality of the diamond formed, or (iii) interacts with other gaseous species present in the program to influence the outcome of the program.

In a preferred method of the above invention, wherein a gaseous impurity is at least partially produced without intentional addition, the concentration of the program is generally such that if it occurs as a single gaseous impurity, it will be incorporated into the diamond lattice or with the diamond's growth surface. Interactions, or interactions with other gaseous species present in the program, can significantly affect the results of the program, and in particular degrade the color or increase the optical absorption of the material. The definition of gaseous impurities specifically excludes noble gases, halogens, oxygen, and hydrogen, and specifically includes elements such as B, P, S, Si, and the like. Further, as a specific and unique exception to the condition that the elemental state of the impurity is a solid at room temperature, any form of nitrogen (e.g., N ₂ , NH ₂ ) in this specification is also regarded as a gaseous impurity.

In particular, the emergence of nitrogen is known to affect growth processes. Previously, the manufacture of high purity diamonds or colorless diamonds showed that the electronic properties described in WO 01/96634 had to be controlled to a nitrogen level of less than 300 ppb. Within this specification, nitrogen above 300 ppb (in N ₂ measurements, or to equivalents of nitrogen such as NH ₃ other forms) is tied to a gaseous impurities.

Accordingly, the method of the above invention provides means for fabricating high chroma diamonds from a growth process comprising greater than 300 ppb, more preferably greater than 500 ppb, more preferably greater than 1 ppm, even more preferably greater than 2 ppm, more preferably greater than Nitrogen at a concentration of 5 ppm, more preferably greater than 10 ppm, optimally greater than 20 ppm or higher.

As mentioned above, preferably at least nitrogen is present in the synthetic atmosphere as a gaseous impurity. Thus, the above described method of the invention can be used in two different ways, with the nitrogen level in the first being carefully controlled, while in the second preferred method the nitrogen level is only controlled to remain below the manufacturing high color. The degree to which a low limit is required for normal diamonds.

In the first method in which nitrogen is carefully controlled, its primary advantage is that the uncontrolled impurities are not nitrogen, and nitrogen can be used to reduce its effect. For example, boron contamination in a CVD chamber is very continuous, even if low levels of boron add significant blue to the synthesized diamond. However, the use of carefully controlled nitrogen additions (in the form of N ₂ or any other N containing gas) to compensate this boron and reduce its effect to the color of the diamond. In addition, there may be an effect of modifying the added nitrogen and, in particular, reducing the amount of boron in the ingested solids. Those skilled in the art will appreciate that this technique can be applied to contaminants that are not boron.

However, a preferred method of the above invention is to cope with the more common problem of nitrogen occurring at a level higher than that required for normal color synthesis of high chroma diamonds. For example, a process gas containing significant levels of nitrogen impurities may be selected, or the process chamber may have a small leak, or nitrogen may enter the process by other components. In these cases, the reduction in nitrogen levels can be expensive.

By carefully adding selected gaseous impurities to the gas phase of the growth process, which may affect the growth process and which itself can be incorporated into the diamond, the nitrogen present in the growth process can be reduced for the color of the diamond produced. influences. In particular, the benefit to chromaticity may be due to the incorporation of impurities that may be used to compensate for the deliberate addition of nitrogen, or it may reduce nitrogen uptake during growth, or it may simply reduce the deleterious effects of nitrogen on diamond chromaticity. Or it can provide a merger of these effects.

To this end, a preferred embodiment of one of the above-described methods of the present invention includes modifying the effect of nitrogen on the chromaticity produced by the growth process and/or the diamond, and in particular reducing if the nitrogen below it is present as the only gaseous impurity. The optical absorption of the diamond that occurs will be used to improve the controlled addition of gaseous impurities, one of its chromaticities. This gaseous impurity may be any of B, Si, S, and P, but is not limited thereto. This gaseous impurity is more preferably B or Si, and is most preferably Si.

Thus, one such selected impurity is boron, which may be added to the gas phase, for example, in the form of diborane. In the presence of boron, nitrogen intake can be reduced depending on precise concentrations and growth conditions, and boron can compensate for the nitrogen being ingested. In addition, boron appears to reduce the deleterious effects of nitrogen intake on diamond color. One difficulty with boron is that too much boron will make the diamond blue, so it is necessary to optimize the boron level for the nitrogen level and carefully control it.

As is well known, the ratio of nitrogen incorporation in CVD diamond growth is generally much lower than boron. As a result, when the target achieves a degree of equilibrium for the nitrogen and boron levels incorporated into the solid to achieve compensation, the boron level added to the gas phase may be much lower than the nitrogen level present, and preferably less 10 Double factor, better 30 times smaller factor, best smaller 100 times factor. In view of the need to balance boron and nitrogen to at least some extent, since the relative uptake of impurities varies between growth stages, this method has the best efficacy and therefore preference when the final object from the material is limited to a single diamond growth stage. This method.

Deliberately added boron, such as diborane or some other boron-containing gas, is preferably greater than 0.5 ppb (parts per billion, or the number of diborane molecules per 10 ⁹ molecules present in the gas phase, as Preferably, the influent stream appears before dissociation), more preferably greater than 0.1 ppb, more preferably greater than 2 ppb, more preferably greater than 5 ppb, more preferably greater than 10 ppb, more preferably greater than 20 ppb, more preferably greater than 50 ppb, optimal Provided at concentrations greater than 0.1 ppb.

When nitrogen is present in the program as an impurity, it is deliberately added to the program to improve one of the chromaticities. When 矽 occurs, it is known that the system is ingested into the diamond and is known to form a 737 nm luminescence center especially when nitrogen is present. This center does not affect the visible color of the diamond. However, this invention discloses that the addition of a lanthanide in the form of a decane at a suitable concentration to the gas phase results in a substantial reduction in the effect of any nitrogen present as a gaseous impurity on the color of the diamond. This mechanism may be one of the centers of defects typically produced by reducing nitrogen intake or simply reducing nitrogen uptake, or may have a compensatory effect, but this is the case for previously reported p-type dopants in diamonds. It will be amazing. However, in the case of 矽, the additional minimum 添加 will have a much larger margin than the minimum required for the observed chromaticity without any detrimental effect on the observed chromaticity, so that The program is easier to apply than boron. Therefore, it is preferred to use hydrazine compared to the use of boron. In particular, because sufficient Si can be added until all of the desired growth stages exhibit the desired degree of colorlessness, it is less desirable to limit the product to materials from a single growth stage.

The precise concentration of germanium dopant required to achieve this effect will depend, in part, on other process conditions such as program power, pressure, substrate temperature, etc., but those skilled in the art will be able to adapt the conditions provided herein to themselves. Specific synthetic systems without undue difficulty.

Deliberately added hydrazines such as decane or some other hydrazine-containing gas form are preferably greater than 0.01 ppm (parts per million or every 10 ⁶ parts, equal decane molecules: all gas molecules appear in the intake before dissociation More preferably in the stream), more than 0.03 ppm, more preferably more than 0.1 ppm, more preferably more than 0.2 ppm, more preferably more than 0.5 ppm, more preferably more than 1 ppm, more preferably more than 2 ppm, more preferably more than 5 ppm, more preferably more than 10 A concentration of ppm, optimally greater than 20 ppm is provided.

The CVD diamond material itself preferably comprises a significant level, or preferably more than one impurity, wherein the impurities may be one or more of the following: a) solid phase boron, greater than 10 ^{1 4} atomic centimeters ^{- 3} , preferably greater than 3 x 10 ^{1 4} atomic centimeters ^{- 3} , preferably greater than 10 ^{1 5} atomic centimeters ^{- 3} , more preferably greater than 3 x 10 ^{1 5} atomic centimeters ^{- 3} , more preferably greater than 10 ^{1 6} atomic centimeters ^{- 3} , more preferably greater than 3 x 10 ^{1 6} atomic centimeters ^{- 3} , optimally greater than 10 ^{1 7} atomic centimeters ^{- 3} concentration; b) solid enthalpy, greater than 10 ^{1 4} atomic centimeters ^{- 3} , preferably greater than 3 x 10 ^{1 4} atomic centimeters ^{- 3} , Preferably greater than 10 ^{1 5} atomic centimeters ^{- 3} , more preferably greater than 3 x 10 ^{1 5} atomic centimeters ^{- 3} , more preferably greater than 10 ^{1 6} atomic centimeters ^{- 3} , more preferably greater than 3 x 10 ^{1 6} atomic centimeters ^{- 3} , optimal greater than ¹⁰¹⁷ atoms cm ^{- 3} the concentration; c) solid nitrogen is greater than ⁵ x 10 ¹ 5 atoms cm ^{- 3,} preferably greater than ¹⁰¹⁶ atoms cm ^{- 3,} more preferably greater than 3 X ¹⁰¹⁶ atoms cm ^{- 3} , optimally greater than 10 ^{1 7} atomic centimeters ^{- 3} concentration. Preferably, the nitrogen is present next to at least one other impurity, and the other impurity is more preferably B or Si and satisfies the criterion for the above-mentioned boron and bismuth, and is preferably Si and satisfies the criterion for the above-mentioned enthalpy. Although nitrogen at these levels is known in CVD diamonds, it is not known to be associated with high chroma gems of high chroma, especially in high definition and significant size.

Those skilled in the art will appreciate that embodiments of the above methods can in principle be applied to many other combinations of impurities in diamonds, such as boron and sulfur or boron and phosphorus, or antimony and sulfur, or antimony and phosphorus, but will appear in the growth process. One of these impurities, which is an uncontrolled impurity, is a far less common phenomenon.

Since deliberately added impurities may reduce the intake of uncontrolled impurities, the electronic properties of the resulting material may be improved compared to those not intentionally added, but typically will not exceed those from, for example, WO 01/ Those obtained by the high purity program such as those disclosed in 96634. In this context, improved electronic properties may include increased activity, lifetime, charge collection distance, and the like.

The diamond layer of the above invention preferably has a "high crystal quality". "High crystalline quality" herein may permit the presence of impurity atoms and associated point defects, but may be affected, for example, by causing excessive scattering, or color, or reduced intensity or handleability lower than required for a predetermined optical application. The use of differential beams or other extended defects in materials used in optical applications constitutes a limitation.

Another aspect of the above invention is that the high chroma CVD diamond of the present invention can be prepared in the form of a gemstone. These stones can be of high quality. One of the four key quality parameters in the gem quality rating is the clarity of the diamond gemstone. The clarity levels used are generally defined by GIA (American Gem Society) and are from FL (no flaw), IF, VVS1 (very very slight inclusions), VVS2, VS1 (very slight inclusions), VS2, SI1 (slight inclusions), SI2, I1 (imperfect), I2 and I3 scale operations. The clarity is such that no visible defects are present in the gemstone, and poor substrate preparation and/or impure process gases are often used in CVD diamond growth procedures to produce inclusions or other characteristics in the diamond that degrade clarity.

It is desirable to have high definition in gemstones, particularly in conjunction with high chroma, but it has not previously been known to produce high chroma and high definition materials in the presence of significant impurities in the process or in subsequent materials. In particular, the method of the present invention provides high chroma growth in the process of one or more of the presence of significant gaseous impurities and, in a preferred embodiment, a significant level of such gaseous impurities in the solid. The material, wherein the clarity is better than I1, better than SI1, better than VS2, better than VS1, better than VVS2, better than VVS1, and most preferably no flaw.

The above invention provides a CVD single crystal diamond material having a high chroma, low optical absorption, and preferably high definition diamond, preferably having a thickness of more than 0.1 mm, more preferably more than 0.2 mm, more preferably more than 0.5 mm, more Preferably, the thickness is more than 1 mm, more preferably more than 2 mm, more preferably more than 2.5 mm, more preferably more than 3 mm, most preferably more than 3.5 mm, wherein the layer contains significant impurities or grows in the presence of significant gaseous impurities. .

The above invention further provides a CVD diamond produced by the single crystal diamond layer polished in the form of a gemstone, characterized by having three orthogonal dimensions of greater than 2 mm, preferably greater than 2.5 mm, and more preferably greater than 3.0 mm. At least one of the axes is configured along the <100> crystal direction or along the main axis of symmetry of the stone body. The diamond will have one or more of high quality and may have the above characteristics.

For the manufacture of the uniform high chroma single crystal CVD diamond material of the present invention described above, growth must occur on the surface of a diamond having substantially no crystal defects. In this context, defects mainly refer to displacement and micro-cracks, but also include double boundaries, point defects, low-angle boundaries, and any other disturbances to the crystal structure. The substrate is preferably a low birefringence type Ia natural, Ib or IIa high pressure/high temperature synthetic diamond or a CVD synthetic single crystal diamond. Defects can degrade materials in two ways, creating stresses, cracks, and associated preferred addresses for chrominance defect formation, and negatively affecting localized uptake of impurities. Because the differential operation occurs during thick layer growth, the differential control during the substrate and during the early stages of growth is particularly important.

The defect density is most easily characterized by optical evaluation after the use of an optimized plasma or chemical etch to reveal defects (referred to as a reveal plasma etch) (e.g., using a short plasma etch of the type described below). Two types of defects can be revealed: 1) the quality of the substrate material is intrinsic. In selected natural diamonds, the density of these defects can be as low as 50/cm 2 , more typically 10 ² /cm ² , and in other cases 10 ⁶ /mm ^ 2 or more.

2) Caused by polishing, including the differential structure and the formation of micro-cracks along the polishing line to form a trembling track (sometimes referred to as a bump track). The density can vary significantly from sample to sample, with typical values ranging from 10 ² /cm ² to less than 10 ⁴ /cm ^{2 in} poorly polished areas or samples.

The preferred low density of the defects is such that the density of the surface etch characteristics associated with the defects as described above is less than 5 x 10 ³ /cm ² , more preferably less than 10 ² /cm ² .

Therefore, defects at or below the surface of the substrate where CVD growth occurs can be minimized by carefully preparing the substrate. Since each stage affects the density of defects in the material at the plane where the surface of the substrate will eventually form when the substrate is completed, the preparation here includes self-mineral reclaimed material (in the case of natural diamonds) or synthetic (in the case of synthetic materials) Medium) Any procedure applied to the material. Specific processing steps may include conventional diamond procedures such as mechanical sawing, grinding and polishing (in this application, specifically optimized to produce low defect levels), and such as laser processing or exit implant and excavation techniques. Lesser-known techniques such as chemical/mechanical polishing, and liquid and plasma chemical processing techniques. In addition, the surface R _Q should be minimized (the root mean square difference between the surface profile measured by the stylus profilometer and the flat portion, preferably measured over 0.08 mm), and the typical value before any plasma etch is no more than a few Meter, that is, less than 10 nm.

One particular method of minimizing surface damage to the substrate is a field plasma etch on the surface on which the growth of the homogeneous epitaxial diamond occurs. In principle, this etch does not need to be on site and does not need to be in front of the growth process, but it will be of maximum benefit if located at the site, as this avoids any further physical or chemical contamination hazards. When the growth process is also based on plasma, on-site etching is generally the most convenient. Plasma etching can use conditions similar to those of deposition or diamond growth procedures, but there are no carbon source gases present and are generally at a slightly lower temperature to provide better etch rate control. For example, it may be composed of one or more of the following: (i) an oxygen etch, which primarily uses hydrogen and, if desired, a small amount of Ar and a small amount of O _{2 required} . Typical oxygen etching conditions are 50 to 450 x 10 ² Pa pressure, an etching gas containing 1 to 4% oxygen content, 0 to 30% argon content and the balance being hydrogen, all percentages based on volume, 600 to 1100 ° C Substrate temperature (typically 800 ° C) and a typical time course of 3 to 60 minutes; (ii) hydrogen etching, similar to (i) but no aerobic; (iii) can be used not only argon, hydrogen And oxygen-based alternative etching methods, such as the use of halogens, other inert gases or nitrogen.

In general, the etch process involves an oxygen etch followed by a hydrogen etch followed by direct transfer to synthesis by introduction of a carbon source gas. The etch time/temperature is selected to be able to remove residual surface damage from the process and remove any surface contaminants, but does not form a highly roughened surface and does not extend along defects such as intersections with the surface and thus causing deep pits. Widely etched. Due to the aggressiveness of the etch, the chamber design and material selection at this stage must be such that the assembly does not allow the material to be transferred into the gas phase by the plasma or transferred to the surface of the substrate. Hydrogen etching after oxygen etching is less specific to crystalline defects, and rounding will aggressively attack the edges caused by oxygen etching of such defects and provide a smoother, better surface for subsequent growth.

The surface of the diamond substrate on which the CVD diamond grows is preferably a {100}, {110}, {113} or {111} surface. Due to processing constraints, the actual sample surface orientation will differ from these ideal orientations by a maximum of 5. In some cases, the highest difference is 10°, but it is less than ideal because it will negatively affect the reproducibility.

The above method of the present invention can be further combined with post-growth treatment such as annealing. In this context, annealing can occur at a temperature and pressure range, from near atmospheric annealing at temperatures as low as 1000 ° C to 1800 ° C, and high pressure annealing in graphite or diamond stabilizing regions at temperatures ranging from 1200 ° C to 3000 ° C.

There are three visual attributes for chromaticity: hue, luminosity, and saturation. Hue is a color attribute that allows it to be classified as red, green, blue, yellow, black or white, or between adjacent pairs or groups of three basic tones (Stephen C. Hofer, colored diamonds) Collection and Classification, 1998, Ashland Press, New York).

White, gray and black objects are differentiated from a light to dark shade. The luminosity is a color attribute defined by the degree of similarity by a neutral achromatic ruler that progressively passes through the darker level of gray and ends in black.

The saturation is a color attribute defined by the degree of difference from an achromatic color of the same luminosity. It is also a descriptive term corresponding to color intensity. The diamond industry uses adjectives such as strong, powerful and realistic to represent the different degrees of saturation of visual assessment. In the CIELAB color system, the saturation is the degree of departure from the neutral color axis (defined by saturation = [(a ^* ) ² + (b ^* ) ² ] ¹ / ² , see below). The luminosity is a visual quality that is perceived separately from saturation.

In cases where materials with specific absorption properties have grown to a finite thickness, absorption spectra measurements from a thin parallel side plate of the material can be used to predict a thicker uniform material if it has the same absorption coefficient spectrum. The polishing of the plate is a round bright style, which will be a useful way. A simple routine to achieve this is described here. The first stage of this routine is the deviation of a parallel side panel of material from its CIELAB chromaticity coordinates that measure its transmittance in the visible region of the spectrum.

The perceived color of an object depends on the transmittance/absorption spectrum of the object, the spectral power distribution of the illumination source, and the response curve of the observer's eye. The CIELAB chromaticity coordinates quoted in this specification have been found in the following manner.

CIE L ^* a ^* b color of a parallel side panel of a diamond using a standard D65 illumination spectrum and eye standard (red, green, and blue) response curves (G. Wyszecki and WSStiles, John Wiley, New York-London-Sydney, 1967) The coordinates have been derived from their transmission spectrum using the following relationship (between 350 nm and 800 nm with a 1 nm data gap).

S _λ = transmittance of wavelength λ L _λ = spectral power distribution of illumination x _λ = red response function of the eye y _λ = green response function of the eye z _λ = blue response function of the eye X = Σ _λ [S _λ x _λ L _λ ] / Y ₀ Y = _{λ λ} [S _λ y _λ L _λ ] / Y ₀ Z = Σ _λ [S _λ z _λ L _λ ] / Y ₀ where Y ₀ = Σ _λ y _λ L _λ L ^* = 116 ( Y/Y ₀ ) ^{1 / 3} -16=luminosity (for Y/Y ₀ >0.008856)a ^* =500[(X/X ₀ )-(Y/Y ₀ ) ^{1 / 3} ] (for X/X ₀ > 0.008856,Y/Y ₀ >0.008856)b ^* =200[(Y/Y ₀ )-(Z/Z ₀ ) ^{1 / 3} ](for Z/Z ₀ >0.008856)C ^* =(a ^{* 2} +b ^{* 2} ) ^{1 / 2} = saturated hab = arctan (b ^* / a ^* ) = gray adjustment angle

Modified versions of these equations must be used outside the limits of X/X ₀ , Y/Y _0, and Z/Z ₀ . The modified version is provided in a technical report prepared by Commission Internationale de L'Eclairage (Colormetry (1986)).

It would be normal for a ^* to correspond to the x-axis and b ^* to correspond to the y-axis to depict a ^* and b ^* coordinates on a graph. The positive a ^* and b ^* values correspond to the red and yellow components of the hue, respectively. The negative a ^* and b ^* values correspond to the green and blue components, respectively. The positive quadrant of the graphic covers the hue from yellow to orange to red, and the saturation (C ^* ) is provided by the distance from the origin.

It can be predicted how the a ^* b ^* coordinate of a diamond having a given absorption coefficient spectrum will change as the length of the optical path changes. In order to have this effect, the reflection loss must first be subtracted from the measured absorption spectrum. The absorbance is then scaled to allow for a different path length and then the return loss is added back. The absorption spectrum can be converted to a transmission spectrum to find the CIELAB coordinates for the new thickness. In this way, the model can be used to simulate the dependence of hue, saturation, and luminosity on the length of the optical path to understand how the chromaticity of the diamond with a given absorption property per unit thickness will depend on the length of the optical path.

Since the absorption coefficient gradually increases toward shorter wavelengths, most of the CVD material is brown. The CVD synthetic circular bright form has generally been produced by a homogeneous epitaxial CVD material in a direction that allows the polished stone body table to be oriented parallel to the interface of the diamond substrate deposited with the CVD material. After the substrate is removed and the top and bottom surfaces of the resulting sheet are polished, the absorption/transmission spectrum has collected the saturation values determined in the manner described above. Saturated and trained diamond critics who have been modeled for parallel side plates when polishing round brilliant shapes (a "depth-limited round brilliant") at a depth limited by the thickness of the plates An approximate linearity is found between the numerical chromaticity levels of the finished stone bodies determined from the GIA level, using the following transformation formulas: D=0, E=1, F=2, G=3, H=4, etc. relationship. For medium to weak saturation, the numerical relationship between the brown/pan-brown depth-limited CVD circular bright numerical chromaticity level and the absorption/transmission spectrum from the plate is modeled to saturate (C ^* ). Observe the following approximate relationship: round brilliant numerical chroma level = 2 x C ^*

The observed linearity is supported by the following arguments. Chroma simulation work has shown that for materials with a given absorption property, for low to medium saturation, the path length has an approximation between the C ^* values obtained using the routine self-absorption/transmission spectrum outlined above. Linear relationship. Under a given viewing and lighting condition, the average path length of light that reaches a viewer's eye from a round brilliant form should be proportional to the linear dimension of the stone body. There should then be an approximately linear relationship between saturation for a parallel side panel and saturation for a depth limited circular bright pattern produced from the panel. Previous work has suggested that there is an approximately linear relationship between the chroma level of a polished stone and its saturation. In summary, this implies that there should be an approximately linear relationship between the depth-limited circular bright chromaticity level and the saturation obtained from the absorption/transmission spectrum of the parallel side plates it is polished.

It should be understood from the above discussion that if a relatively thin plate is fabricated, it can be predicted from the absorption/transmission spectrum measured for the plate if a thicker plate of uniform material having the same absorption coefficient spectrum is polished, What is the color of a round bright style? In order to achieve this, the reflection loss must first be subtracted from the measured absorption spectrum. The absorbance is then scaled to allow for a different path length and then the return loss is added back. The absorption spectrum can then be converted to a transmission spectrum to find the CIELAB coordinates for the new thickness (e.g., approximately 3.2 mm for a 0.5 ct circular bright approximation or 3.8 mm for a 1 ct circular bright approximation). When subtracting the reflection loss, it is important to consider the spectral dependence of the reflection coefficient. It can be determined from the wavelength dependence of the refractive index of the diamond provided by F. Peter in Z. Phys. 15, 358-368 (1923). Using the dependence of the reflection loss of a parallel side plate on the refractive index and the standard formula, the effect of the reflection loss on the apparent absorbance can be calculated as a function of the wavelength and the self-measured spectral subtraction can be used to allow a more accurate calculation of the absorption coefficient. Spectrum.

The invention will now be described with reference to the following non-limiting examples. In each of these examples, unless otherwise specified, in order to control nitrogen and thus characterize the utilization of the present invention, nitrogen is removed from the inlet gas stream using a purifier and a high purity gas source, so nitrogen dopants are not intentionally added. In the case of a source, the gas stream contains less than 100 ppb of N ₂ . Then 100 ppm hydrogen typically utilize one of N ₂ mixture of nitrogen was added back to the program, the provider of this gas mixture of nitrogen gas level well controlled, especially in the range of 0.5 to 20 ppm, especially natural. Those skilled in the art will appreciate that the use of lower purity gases or poorer vacuum implementations can easily lead to levels of nitrogen impurities in the process, especially in the range of 1 to 20 ppm or greater, where nitrogen will not be Deliberately added impurities, but due to poor control or cost savings.

Example 1

A lb HPHT substrate suitable for the synthesis of single crystal CVD diamond having a {100} major face is prepared according to the method described in WO 01/96634.

These substrates are brazed to a tungsten substrate using a high temperature diamond brazing material. This was introduced into a microwave plasma CVD reactor and an etching and growth cycle was initiated in the general form described in WO 01/96634 using the specific synthesis conditions described below.

Nitrogen was added to the program using a mixture of 100 ppm N ₂ in hydrogen. Boron impurities were added to the procedure using 20 ppm or 100 ppm of B ₂ H _{6 in} hydrogen.

Two sets of samples were prepared.

Sample group 1-1

The first growth stage comprised 200/250/4500 sccm (standard cubic centimeters per minute) of CH ₄ /Ar/H ₂ at 200 x 10 ² Pa and a substrate temperature of 850 ° C without the addition of dopants. This is a control layer of high purity and high chroma growth controlled by an exemplary program.

The second growth phase is the same as the first phase described above, with 1 ppm of N _{2 added} . This phase evaluates the effect of 1.0 ppm nitrogen as the sole gaseous impurity.

Sample group 1-2

The first growth phase repeats the conditions for the first growth phase of Group 1-1.

The second growth stage was the same as the first stage described above, with 0.003 ppm B ₂ H ₆ added and 1 ppm N _{2 added} .

Upon completion of the growth period, the reactor is removed and processed to produce a range of samples of the test piece (especially the growing cross-sectional slice), while the separate plates of the second stage growth layer are typically 2 to 3 mm thick. Cross-sectional sectioning confirmed that in the first case, the growth of the first stage was basically colorless and high-purity growth, while the growth of the second stage was significantly brown in the sample group 1-1, and the second stage was the second procedure of adding boron. It is almost colorless.

Several further samples were generated using the following general growth conditions: 200/250/4500 sccm (standard cubic centimeters per minute) at a substrate temperature of 200 x 10 ² Pa CH ₄ /Ar/H ₂ and 850 ° C with 0.003 ppm added B ₂ H ₆ , adding 1 ppm of N ₂ , but making small variations for different growth parameters and especially making the temperature change +/- 100 ° C, the B and N concentrations have a relative ratio of 5 times in both directions (eg , relative to nitrogen with higher and lower boron), and a pressure of +/- 100 x 10 ² Pa. The conclusion is that B is a blue material with respect to excessive nitrogen, and a brown material is produced with respect to B with too little nitrogen. The optimum balance between B and N varies to some extent with other program parameters such as pressure and temperature. However, the deleterious effects of nitrogen on the production of brown or optically absorptive diamonds can be improved and substantially stopped by the addition of an optimum level of boron to the process, matching the particular growth conditions employed.

Example 2

A 1b HPHT diamond substrate was prepared as in Example 1 and mounted on a tungsten dish. The dish was introduced into a microwave plasma CVD reactor and an etching and growth cycle was initiated in the general form described in WO 01/96634, but with the specific synthesis conditions described below.

Nitrogen was added to the program using a mixture of 100 ppm of N ₂ in hydrogen. The cerium impurity is added to the procedure using SiH ₄ , typically 500 ppm in hydrogen. Two sets of samples were prepared.

Sample group 2-1

The first growth stage comprised 36/0/600 sccm (standard cubic centimeters per minute) of CH ₄ /Ar/H ₂ at 250 x 10 ² Pa and a substrate temperature of 810 ° C without the addition of dopants. This is a control layer of high purity and high chroma growth controlled by an exemplary program.

The second growth phase is the same as the first phase described above, with 2.0 ppm of nitrogen added. This phase evaluates the effect of 2.0 ppm nitrogen as the sole gaseous impurity.

Sample group 2-2

The first growth phase repeats the conditions for the first growth phase of Group 2-1.

The second growth stage was the same as the first stage described above, with 0.03 ppm of decane added and 2.0 ppm of nitrogen added.

Upon completion of the growth period, the reactor is removed and processed to produce a range of samples of the test piece (especially the growing cross-sectional slice), while the separate plates of the second stage growth layer are typically 2 to 3 mm thick. Cross-section slicing confirmed that in the first case, the first stage of growth was basically colorless and high-purity growth, while the second stage of growth was significantly brown in sample group 2-1, and the second stage grew in the second procedure of adding bismuth. It is almost colorless.

Several further samples were generated using the following general growth conditions: 36/0/600 sccm (standard cubic centimeters per minute) at a substrate temperature of 250 x 10 ² Pa CH ₄ /Ar/H ₂ and 810 ° C, adding 0 to 5 ppm of decane, with 0 to 10 ppm of nitrogen added, but with small variations for different growth parameters and especially for temperature fluctuations of +/- 100 ° C, and pressures of +/- 100 x 10 ² Pa. Specifically, the following combinations were tested and the decane/nitrogen concentration was recorded at a ppm of 0.2:1, 1:1, 5:10. In each case, the effect of decane is to inhibit any brown coloration that would otherwise be produced in the diamond. In addition, the excessive enthalpy required to inhibit brown coloration does not produce any harmful color or other changes in diamond growth. Since the concentration of decane is not important, and the precise value of the nitrogen concentration level or other program parameters of the gas phase becomes far less important, this provides one of the advantages over B in reducing the harmful effects on nitrogen using Si as a gaseous impurity. Additional advantages.

Example 3

A 1b HPHT diamond substrate was prepared as in Example 1 and mounted on a tungsten dish. The dish was introduced into a microwave plasma CVD reactor and an etching and growth cycle was initiated in the general form described in WO 01/96634, but with the following specific synthesis conditions: growth conditions of 36/0/600 sccm (standard cube) The centimeters per minute is at a substrate temperature of 250 x 10 ² Pa C ₄ /Ar/H ₂ and 810 ° C with a decane concentration of 0.25 ppm and a nitrogen concentration of 2 ppm. Continue to grow until the CVD layer thickness is 2 mm. After the growth procedure is terminated, the sample is removed and processed to produce one of the individual parallel side plates of the single crystal CVD diamond. The other is processed to produce a {100} cross-sectional slice. Characterized CVD separate plate following results: a) SIMS measurements carried out in four places on each side of the plate, indicating approximately 6 x 10 ^{1 5} cm having ^{- 3} (34 ppb) uniform Si concentration.

b) UV/visible/NIR absorption spectroscopy measurements at room temperature indicating an absorption coefficient of less than 0.15 cm ^{- 1} for all wavelengths between 300 nm and 1000 nm. 270 nm absorption coefficient of 0.18 cm ^{- 1,} and, after baseline subtraction, the peak 270 nm absorption coefficient characteristic of 0.036 cm ^{- 1,} indicating that the concentration of uncompensated nitrogen of approximately 24 ppb. 350 nm and 520 nm absorption coefficient of 0.10 and 0.07 cm ^--1.

c) A 0.5 ct round brilliant CIELAB chromaticity coordinate system generated for this type of material is estimated using the self-absorption spectroscopy data described earlier and found to be: L ^* = 87.9, a ^* = -0.13, b ^* =1.07, C ^* =1.08

Using the method described earlier, it can be inferred that a stone body having these chromaticity coordinates will have a FGIA chromaticity level.

d) Perform absorption spectrum at 77K, indicating that it has 6.02 meV. Cm ^{- 1} absorption coefficient product set of strong 737 nm feature.

e) Photoluminescence spectroscopy was performed at 77 K with a excitation of 633 nm, indicating a Raman normalization intensity of 4 for the Si-related property of 737 nm.

f) Photoluminescence spectroscopy with a 514 nm excitation at 77 K, indicating photoluminescence characteristics of 575, 637 and 737 nm with the following Raman normalization intensity:

g) Photoluminescence spectroscopy at 77 K with 325 nm excitation, indicating photoluminescence characteristics of 533 nm and 575 nm.

A cross-sectional slice of the feature lines following results: a) SIMS measurements again indicated a dominant <100> Segment of approximately 6 x 10 ^{1 5} cm for ^- a Si concentration of ³ (34 ppb) of. A significantly higher Si concentration was measured for the secondary <100> segment that had been formed by the {100} edge face growth from the substrate. Subarea, optical microscopy indicated a nearly colorless, the Si concentration was found above ^1,018 cm ^{- 3} (5.7 ppm).

b) The photoluminescence spectrum collected at 77K with 633 nm excitation shows a strong Si-related property of 737 nm, which has a Raman normalization intensity of approximately 4 for the dominant <100> segment and is secondary < 100> increased to almost 40 in the segment.

c) A luminescence image of the CVD material, which is generated by the above-described band gap excitation, dominated by orange-red illumination.

Example 4

A 1b HPHT diamond substrate was prepared as in Example 1 and mounted on a tungsten dish. The dish was introduced into a microwave plasma CVD reactor and an etching and growth cycle was initiated in the general form described in WO 01/96634, but with the following specific synthesis conditions: growth conditions of 36/0/600 sccm (standard cube) The centimeters per minute is at a substrate temperature of 250 x 10 ² Pa C ₄ /Ar/H ₂ and 810 ° C with a decane concentration of 0.25 ppm and a nitrogen concentration of 1 ppm. Continue to grow until the CVD layer thickness is 0.7 mm. After the growth procedure is terminated, the sample is removed and processed to produce one of the individual parallel side plates of the single crystal CVD diamond. The other is processed to produce a {100} cross-sectional slice. Characterized CVD separate plate following results: a) SIMS measurements carried out in four places on each side of the plate, indicating approximately having ⁵ x 10 ¹ 5 cm ^- uniform Si concentration of ³ (28 ppb) of.

b) UV/visible/NIR absorption spectroscopy measurements at room temperature indicating an absorption coefficient of less than 0.5 cm ^{- 1} for all wavelengths between 300 nm and 1000 nm. The absorption coefficient of 270 nm is 0.5 cm ^{- 1} , and after the baseline subtraction, the peak absorption coefficient of the 270 nm characteristic is 0.074 cm ^{- 1} , indicating an uncompensated nitrogen concentration of approximately 50 ppb. 350 nm and 520 nm were 0.32 and absorption coefficient of 0.28 cm ^--1.

c) A 0.5 ct round brilliant CIELAB chromaticity coordinate system generated for this type of material is estimated using the self-absorption spectroscopy data described earlier and found to be: L ^* = 84.0, a ^* = -0.19, b ^* =-0.43, C ^* =0.47

Using the method described earlier, it can be inferred that a stone body having these chromaticity coordinates will have an E GIA chromaticity level.

d) Perform absorption spectrum at 77K, indicating that it has 5.41 meV. Cm ^{- 1} absorption coefficient product set of strong 737 nm feature.

e) Photoluminescence spectroscopy was performed with a 633 nm excitation at 77 K, indicating a Raman normalization intensity of approximately 0.99 nm for the Si-related property of approximately 0.90.

f) Photoluminescence spectroscopy with a 514 nm excitation at 77 K, indicating photoluminescence characteristics of 575, 637 and 737 nm with the following Raman normalization intensity:

g) Photoluminescence spectroscopy at 77 K with 325 nm excitation, indicating photoluminescence characteristics of 533 nm and 575 nm.

Wherein a cross-sectional slice of the system provides the following results: a) SIMS measurements again indicated for the dominant <100> Segment of approximately ⁵ x 10 ¹ 5 cm ^{- 3} (28 ppb) of a Si concentration. A significantly higher Si concentration was measured for the secondary <100> segment that had been formed by the {100} edge face growth from the substrate. Subarea, optical microscopy indicated a nearly colorless, the Si concentration was found above ^1,018 cm ^{- 3} (5.7 ppm).

b) The photoluminescence spectrum collected at 77K with 633 nm excitation shows a strong Si-related property of 737 nm, which has a Raman normalization intensity of approximately 1 for the dominant <100> segment and is secondary < 100> increased to almost 4 in the segment.

c) A luminescence image of the CVD material, which is generated by the above-described band gap excitation, dominated by orange-red illumination.

Example 5

A one-layer single crystal CVD diamond sample was grown on a {100} HPHT synthetic substrate in six different stages. The gas flow rate was 36/600 sccm (standard cubic centimeters per minute) of CH ₄ /H ₂ and the substrate temperature was 810 °C. Nitrogen and decane are supplied to provide the concentrations listed in Table 3 below for different stages of the growth procedure in the process gas. Growth ends at a total thickness of 1.4 mm when CVD is grown.

A {100} polished cross-section slice is processed from the sample to enable the study of the properties of the layer. When the sections were viewed under an optical transmission microscope, the CVD grew to be uniform and colorless. However, different layers corresponding to different growth stages can be clearly discerned in the luminescence image of the slice recorded by the above-described band gap excitation. It can also be readily identified in a cathodoluminescence image recorded by a scanning electron microscope equipped with an Oxford instrument low magnification cathodoluminescence imaging system. A MonoCL spectrometer was used to measure the intensity of the 235 nm free exciton luminescence emitted by each layer under electron beam excitation. Table 3 lists the gas phase enthalpy and nitrogen concentrations, the enthalpy concentration produced by SIMS and the free exciton luminescence intensity measured relative to a standard sample of high purity CVD diamond.

This example shows that even with a significant concentration of yttrium and growing in the presence of a nitrogen concentration that would normally cause the material to exhibit a weak free exciton emission, the growing diamond exhibits a surprisingly strong free exciton luminescence (relative to a high As measured by the purity diamond standard). At the highest enthalpy concentration achieved by the higher gas phase nitrogen concentration, the free exciton emission system is significantly weaker, but the material still traverses the spectrally visible region with a very low absorption coefficient and is therefore colorless. The absorption coefficient spectrum is derived from the absorbance measurement (after subtracting the calculated reflection loss spectrum) and the absorption coefficient in the 350 to 800 nm is found to be less than 0.9 cm ^{- 1} for all positions across the sample and only at 737 nm. Raise to above 0.7 cm ^{- 1} .

Example 6

A one-layer single crystal CVD diamond sample was grown on a {100} HPHT synthetic substrate in five different stages. The gas flow rate was 36/600 sccm (standard cubic centimeters per minute) of CH ₄ /H ₂ and the substrate temperature was 883 °C. Nitrogen and decane are supplied to provide the concentrations listed in Table 4 below for different stages of the growth procedure in the process gas. Growth ends at a total thickness of 1.2 mm when CVD is grown.

A {100} polished cross-section slice is processed from the sample to enable the study of the properties of the layer. Different layers corresponding to different growth stages can be clearly discerned in the luminescence image of the slice recorded by the above-described band gap excitation. It can also be readily identified in a cathodoluminescence image recorded by an SEM equipped with an Oxford instrument low magnification cathodoluminescence imaging system. A MonoCL spectrometer was used to measure the intensity of the 235 nm free exciton luminescence emitted by each layer under electron beam excitation. Table 4 lists the gas phase enthalpy and nitrogen concentrations, the enthalpy concentration produced by SIMS measurement and the intensity of the free exciton luminescence measured relative to a standard sample of high purity CVD diamond.

When the sections were viewed under an optical transmission microscope, it was found that except for the slightly gray final layer, the CVD growth was uniform and colorless. At 77 K, the absorption spectrum indicates that in addition to the well-known Si-related lines of 737 nm, this last layer also shows absorption lines of approximately 945.3 nm, 830.1 and 856.8 nm and these lines and approximately 750 nm. The wide increase in absorption between the two. This higher level of absorption is observed across the entire visible spectrum, resulting in a gray appearance. The absorption coefficient spectrum is derived from the absorbance measurement (after subtracting the calculated reflection loss spectrum). For all positions in the first four samples, the absorption coefficient was found to be less than 1 cm ^{- 1} between 350 and 800 nm, and only increased from 737 nm to above 0.8 cm ^{- 1} . For the final layer, the absorption coefficient was found located 0.9 cm ^{- 1} to 2.1 cm ^- between ¹ only rises above 737 nm in the 1.5 cm ^{- 1.}

Example 7

A one-layer single crystal CVD diamond sample was grown on a {100} HPHT synthetic substrate in four different stages. The gas flow rate used was CH ₄ /Ar/H ₂ of 250/60/4000 sccm and the substrate temperature was 825 °C. Table 5 lists the N ₂ and B ₂ H ₆ process gas concentrations supplied for each growth stage, as well as the corresponding concentrations of atomic nitrogen and boron in each layer of the sample (as measured by SIMS). The total thickness of the deposited CVD material is 1.0 mm.

A {100} polished cross-sectional slice was taken from the sample to study the layers. Figure 3 shows a low magnification optical microscope image of this sample showing the CVD growth phase.

The layer corresponding to the first growth stage is carried out under the procedural conditions for the growth of high purity CVD diamond, and as such, this thin initial layer has a high chroma. For subsequent growth stages, the nitrogen level of the gas phase is set to the level at which an uncontrolled air leaks into the gas system, where the size of this leak will introduce sufficient nitrogen to result in a poor crystalline quality CVD material. Figure 3 shows that, despite the high nitrogen concentration in the process gas mixture, reasonable color and good crystallinity are maintained in the layers corresponding to the second and third growth stages. This is due to the amount of diborane added to the program, which improves the negative effects of nitrogen. In particular, the boron incorporated into the material inhibits excessive surface roughening and subsequent material degradation and additionally provides compensation for the nitrogen donor. In the fourth growth phase, the diborane in the process gas mixture is now below the level at which the surface roughening is inhibited and the boron incorporated into the material completely compensates for the nitrogen. Therefore, the material changes to black and has poor crystalline properties. The increase in boron and nitrogen concentrations measured in the material can be explained by the increased surface roughness, which results in a general increase in the impurity uptake value.

Example 8

A one-layer single crystal CVD diamond sample was grown on a {100} HPHT synthetic substrate in seven different stages. The gas flow rate used was CH ₄ /Ar/H ₂ of 250/60/4000 sccm and the substrate temperature was 805 °C. Table 6 lists the N ₂ and B ₂ H ₆ process gas concentrations supplied for each growth stage, as well as the corresponding concentrations of atomic nitrogen and boron in each sample (as measured by SIMS). The total thickness of the deposited CVD material was 1.2 mm.

In this example, although a fixed concentration of diborane in the process gas mixture may be due to small changes in reactor conditions such as temperature, the boron incorporated into the material increases steadily as a function of growth time. In each of the growing layers, the boron incorporated into the material is greater than the incorporation of nitrogen, thus achieving complete compensation for the nitrogen donor. Thus, similar to Example 6, the material can tolerate a relatively high amount of nitrogen without degradation as long as the full compensation of the nitrogen donor is maintained.

Exciton frequencies were measured in each layer of the sample using an SEM system equipped with an Oxford Instrument Cathodoluminescence (CL) system. The spectrum is recorded at liquid nitrogen temperature and the ratio of boron bound exciton intensity to free exciton intensity is calculated from each spectrum. In addition, the exciton intensity is compared to the free exciton intensity in a standard sample of high purity CVD diamond. The boron bound exciton intensity is as expected to have a cross-correlation with the increased boron concentration in the material. Furthermore, the free exciton intensity relative to the high purity standard sample is reduced by a function of increased boron incorporation, which is consistent with the increase in boron bound exciton intensity. It is clear that the free exciton intensity relative to standard high purity samples is as high as the nitrogen level in the material. For example, for a boron-free, but only 0.08 ppm nitrogen CVD sample, a free exciton intensity of <10% relative to a standard high purity sample has been measured. This is further evidence of the improved effect of boron in the presence of high nitrogen levels: the effect of boron is to prevent surface roughening associated with high nitrogen uptake, which inhibits other point defects that would normally extinguish the excitability of free excitons. Ingestion.

This compensating effect also results in high chroma materials compared to the case where nitrogen has not yet appeared. In layer 6 of Table 6, where the gas phase nitrogen is reduced to 1 ppm, the layer is significantly visible due to the presence of blue, as compared to the relatively higher chroma of layers 5 and 7.

Example 9

A 50 mm diameter molybdenum substrate was prepared for growth of a polycrystalline CVD diamond layer. Before starting to grow, gas chromatograph measurements were used to determine the uncontrolled nitrogen concentration of 2.5 ppm in the growing environment. This nitrogen concentration will generally result in a polycrystalline diamond layer of poor quality. A decane addition to 100 ppm of decane in hydrogen was made to approximate the ruthenium concentration in the gas phase to 1.5 ppm. Addition of H ₂ /Ar/CH ₄ gas composition of 600/10/23 sccm at a temperature of 880 ° C and a pressure of 200 x 10 ² Pa, 9.5 sccm of 100 ppm SiH _{4 in} H ₂ (equivalent to ~ in the gas phase) One of the 1.5 ppm 矽) plasma-assisted CVD programs began to grow.

The growth lasted for more than 75 hours and a polycrystalline layer was removed with a thickness of approximately 500 microns when measured with a micrometer with sharp diamonds. The appearance of the layer was light gray and the crystal quality was judged to be good without evidence of porosity.

Optical properties were measured by laser cutting a few 10 x 10 mm squares from the layer. The material is transparent at the visible wavelength and has a slight gray color.

C ^* . . . saturation

z _λ . . . Blue response function of the eye

Hab. . . Gray adjustment angle

△n. . . Difference in refractive index of light parallel to slow and fast axis polarization (ie, birefringence)

L. . . Thickness of sample

L _λ . . . Spectral power distribution of illumination

S _λ . . . Transmittance of wavelength λ

△n. . . L optical retardation

x _λ . . . Red response function of the eye

δ. . . Phase shift

y _λ . . . Green response function of the eye

λ. . . Wavelength of light

Figure 1 shows the spectral decomposition of the UV/visible absorption spectrum of an orange-brown CVD diamond layer, representing the presence of nitrogen without the application of a typical CVD diamond layer grown by the method of the present invention. Spectrum A shows a type 1b HPHT synthetic diamond, spectrum B shows an original spectrum of orange-brown CVD diamonds, spectrum C shows a spectral component with (wavelength) ^{- 3} dependence, and spectrum D shows a mixture of two broad absorption bands. Spectral component; Figure 2 shows the photoluminescence spectrum of one of the erbium-doped CVD diamond samples recorded at 77 K by 785 nm laser excitation; and Figure 3 shows the same as described in Example 7. A low magnification optical microscopy image.

Claims (29)

A method for forming a CVD diamond, the method comprising: (i) providing a substrate; (ii) providing a CVD synthesis atmosphere in which a nitrogen-containing gas having a concentration of nitrogen molecules greater than 300 ppb is present; and (iii Adding a gas containing boron or lanthanum to the CVD diamond synthesis atmosphere, wherein the boron or lanthanum is added to the CVD diamond synthesis atmosphere in a controlled manner to reduce the CVD caused by nitrogen for the single crystal CVD The detrimental effect of the chromaticity of the diamond to produce a single crystal CVD diamond in which at least 80% of the volume of the single crystal CVD diamond has at least one of the following characteristics (a) to (e): (a An absorption spectrum, measured at room temperature, so the standard 0.5 ct round brilliant chromaticity will be superior to the chromaticity of K on the GIA gem diamond ruler; (b) measured at room temperature at 270 奈An absorption coefficient of less than 2.9 cm ^-1 for rice; (c) an absorption coefficient of less than 1.5 cm ^-1 at 350 nm measured at room temperature; (d) less than 0.45 cm at 520 nm measured at room temperature ^- an absorption coefficient of ^1; or (e) an absorption at 0.18 cm ^-1 of less than 700 nm measured at room temperature The main volume number, wherein the single crystal CVD diamond having a thickness greater than 0.1 mm, the volume of which is mainly in the single crystal CVD diamond of greater than the concentration of nitrogen-based 5x 10 ¹⁵ atoms / cm ^, and wherein the single crystal CVD diamond of The concentration of boron or cerium in the medium is greater than 10 ¹⁴ atoms/cm 3 . The method of claim 1, wherein the lanthanide is added to the CVD diamond synthesis atmosphere. The method of claim 2, wherein a concentration of nitrogen in a majority of the volume of the diamond layer is less than or equal to 2 x 10 ¹⁷ atoms/cm 3 , and a concentration of germanium in a majority of the volume of the diamond layer is less than Or equal to 2 x 10 ¹⁸ atoms / cubic centimeter. The method of claim 2, wherein the ratio of the concentration of nitrogen to the concentration of cerium in the majority of the volume of the diamond layer is from 1:20 to 20:1. The method of claim 2, wherein the nitrogen-containing system is present in the synthesis atmosphere at a concentration greater than 300 ppb, and the helium-containing gas is present in the synthesis atmosphere at a concentration greater than 10 ppb. The method of claim 1, wherein boron is added to the CVD diamond synthesis atmosphere. The method of claim 6, wherein the ratio of the concentration of nitrogen to the concentration of boron in the majority of the volume of the diamond layer is from 1:2 to 2:1. The method of claim 6, wherein the nitrogen-containing system is present in the synthesis atmosphere at a concentration greater than 300 ppb, and the boron-containing gas is present in the synthesis atmosphere at a concentration greater than 0.5 ppb. The method of claim 1, wherein the CVD diamond layer produced has an increased normalization freedom compared to a method in which the second gas containing a second impurity atom type is not added. Exciton intensity. The method of claim 1, wherein the CVD diamond layer produced has a carrier activity, a carrier lifetime, and a method in which the second gas containing a second impurity atom type is not added. / or one of the charge collection distances increases. The method of claim 1, wherein the synthetic atmosphere comprises a concentration of greater than 300 ppb of the nitrogen-containing gas that has not been intentionally added. The method of claim 1, wherein the first gas is not added in a controlled manner. The method of claim 1, wherein the method comprises one or more of the following characteristics: (1) the substrate is a diamond having a surface which is substantially free of crystal defects such that a plasma etching is exposed A density will be revealed for surface etch characteristics of defects below 5 x 10 ³ /mm ^ 2 ; (2) the single diamond layer has a synthesis time of at least 50 hours; and (3) the substrate contains multiple Separated single crystal diamond substrate. The method of claim 1, wherein the CVD diamond layer is a single crystal, and wherein a majority of the volume of the diamond layer has at least one of the following characteristics: a) an absorption spectrum, measured at room temperature A standard 0.5 ct round brilliant chromaticity will be better than K; b) at 270 nm at room temperature measuring less than 1.9 cm ^-1 one absorption coefficient; c) at room temperature at 350 nm measuring less than 0.90 cm ^{- 1} one absorption coefficient; d) at 520 nm less than 0.30 cm ^-1 absorption; or e) at 700 nm less than 0.12 cm ^-1 absorption. The method of claim 1, wherein the CVD diamond layer is a single crystal and wherein the diamond layer is formed in a gemstone having a triple orthogonal dimension greater than 2 mm, wherein at least one axis is configured along <100> Crystallization direction or along the main axis of symmetry of the gemstone. A CVD diamond layer produced by the method of claim 1 of the patent application. An optical component comprising a CVD diamond layer produced according to the method of claim 1 of the patent application. An electrical or electronic component comprising a CVD diamond layer produced according to the method of claim 1 of the patent application. A CVD diamond layer produced according to the method of claim 1 which has a thickness greater than 0.1 mm. A CVD single crystal diamond layer produced in the form of a gemstone according to the method of claim 1 of the patent application. A CVD single crystal diamond layer according to claim 20, which has three orthogonal dimensions greater than 2 mm, wherein at least one axis is configured along the <100> crystallographic direction or along the major axis of symmetry of the gemstone. A CVD single crystal diamond layer as claimed in claim 20, which has at least one of the clarity of SH on the GIA gem rating. A single crystal CVD diamond layer, wherein at least 80% of the volume of the single crystal diamond layer has at least one of the following characteristics (a) to (e): (a) an absorption spectrum, measured at room temperature The standard 0.5ct round brilliant chromaticity will be superior to the chromaticity of K on the GIA diamond diamond ruler; (b) the absorption coefficient at 270 nm below 2.9 cm ^-1 at room temperature (c) measuring an absorption coefficient of less than 1.5 cm ^-1 at 350 nm at room temperature; (d) measuring an absorption coefficient of less than 0.45 cm ^-1 at 520 nm at room temperature; or (e) Measuring an absorption coefficient of less than 0.18 cm ^-1 at 700 nm, wherein the single crystal CVD diamond has a thickness greater than 0.1 mm, wherein the nitrogen concentration in the main volume of the single crystal CVD diamond is greater than 5 x 10 ¹⁵ atoms/cm 3 , and wherein the concentration of boron or lanthanum in the main volume of the single crystal CVD diamond is greater than 10 ¹⁴ atoms/cm 3 . The CVD diamond layer of claim 23, wherein a majority of the volume of the diamond layer contains ¹⁵ from 10 ¹⁵ to 2 x 10 ¹⁸ atoms/cm 3 . The CVD diamond layer of claim 23, wherein the lanthanide is present in the single crystal CVD diamond layer. A CVD diamond layer according to claim 23, wherein the layer has a thickness greater than 1 mm. The CVD diamond layer of claim 23, wherein the layer has a birefringence of less than 1 x 10 ^-3 at a volume greater than 0.1 cubic centimeters. The CVD diamond layer of claim 23, wherein the diamond layer is a single crystal. The CVD diamond layer of claim 23, wherein the concentration of boron is greater than the concentration of the nitrogen.