SINGLE CRYSTAL CVD SYNTHETIC DIAMOND MATERIAL

• US 20140335339A1
• Filed: 12/12/2012
• Published: 11/13/2014
• Est. Priority Date: 12/16/2011
• Status: Active Grant

• Current Assignee: Element Six (Holdings) Ltd. (Anglo American PLC)
• Original Assignee: Element Six Technologies US Corporation (Anglo American PLC)
• Inventors: Twitchen, Daniel James, Khan, Rizwan Uddin Ahmad, Dhillon, Harpreet Kaur
• Granted Patent: US 9,260,797 B2
• Time in Patent Office: Days
• US Class Current: 428/220
• CPC Class Codes: C30B 21/02 by normal casting or gradient freezing
• CPC Class Codes: C30B 21/04 by zone-melting
• CPC Class Codes: C30B 25/10 Heating of the reaction chamber or the substrate
• CPC Class Codes: C30B 25/16 Controlling or regulating controlling or regulating in general G05
• CPC Class Codes: C30B 25/20 the substrate being of the same materials as the epitaxial layer
• CPC Class Codes: C30B 29/04 Diamond

Abstract

A single crystal CVD synthetic diamond material comprising: a total as-grown nitrogen concentration equal to or greater than 5 ppm, and a uniform distribution of defects, wherein said uniform distribution of defects is defined by one or more of the following characteristics: (i) the total nitrogen concentration, when mapped by secondary ion mass spectrometry (SIMS) over an area equal to or greater than 50×50 μm using an analysis area of 10 μm or less, possesses a point-to-point variation of less than 30% of an average total nitrogen concentration value, or when mapped by SIMS over an area equal to or greater than 200×200 μm using an analysis area of 60 μm or less, possesses a point-to-point variation of less than 30% of an average total nitrogen concentration value; (ii) an as-grown nitrogen-vacancy defect (NV) concentration equal to or greater than 50 ppb as measured using 77K UV-visible absorption measurements, wherein the nitrogen-vacancy defects are uniformly distributed through the synthetic single crystal CVD diamond material such that, when excited using a 514 nm laser excitation source of spot size equal to or less than 10 μm at room temperature using a 50 mW 46 continuous wave laser, and mapped over an area equal to or greater than 50×50 μm with a data interval less than 10 μm there is a low point-to-point variation wherein the intensity area ratio of nitrogen vacancy photoluminescence peaks between regions of high photoluminescent intensity and regions of low photolominescent intensity is <2× for either the 575 nm photoluminescent peak (NV⁰) or the 637 nm photoluminescent peak (NV); (iii) a variation in Raman intensity such that, when excited using a 514 nm laser excitation source (resulting in a Raman peak at 552.4 nm) of spot size equal to or less than 10 μm at room temperature using a 50 mW continuous wave laser, and mapped over an area equal to or greater than 50×50 μm with a data interval less than 10 μm, there is a low point-to-point variation wherein the ratio of Raman peak areas between regions of low Raman intensity and high Raman intensity is <1.25×; (iv) an as-grown nitrogen-vacancy defect (NV) concentration equal to or greater than 50 ppb as measured using 77K UV-visible absorption measurements, wherein, when excited using a 514 nm excitation source of spot size equal to or less than 10 μm at 77K using a 50 mW continuous wave laser, gives an intensity at 575 nm corresponding to NV⁰ greater than 120 times a Raman intensity at 552.4 nm, and/or an intensity at 637 nm corresponding to NV⁻ greater than 200 times the Raman intensity at 552.4 nm; (v) a single substitutional nitrogen defect (N_s) concentration equal to or greater than 5 ppm, wherein the single substitutional nitrogen defects are uniformly distributed through the synthetic single crystal CVD diamond material such that by using a 1344 cm⁻¹ infrared absorption feature and sampling an area greater than an area of 0.5 mm², the variation is lower than 80%, as deduced by dividing the standard deviation by the mean value; (vi) a variation in red luminescence intensity, as defined by a standard deviation divided by a mean value, is less than 15%; (vii) a mean standard deviation in neutral single substitutional nitrogen concentration of less than 80%; and (viii) a colour intensity as measured using a histogram from a microscopy image with a mean gray value of greater than 50, wherein the colour intensity is uniform through the single crystal CVD synthetic diamond material such that the variation in gray colour, as characterised by the gray value standard deviation divided by the gray value mean, is less than 40%.

Claims

1. A single crystal CVD synthetic diamond material comprising:

a total as-grown nitrogen concentration equal to or greater than 5 ppm, and

a uniform distribution of defects, wherein said uniform distribution of defects is defined by one or more of the following characteristics;

(i) the total nitrogen concentration, when mapped by secondary ion mass spectrometry (SIMS) over an area equal to or greater than 50×

50 μ

m using an analysis area of 10 μ

m or less, possesses a point-to-point variation of less than 30% of an average total nitrogen concentration value, or when mapped by SIMS over an area equal to or greater than 200×

200 μ

m using an analysis area of 60 μ

m or less, possesses a point-to-point variation of less than 30% of an average total nitrogen concentration value;

(ii) an as-grown nitrogen-vacancy defect (NV) concentration equal to or greater than 50 ppb as measured using 77K UV-visible absorption measurements, wherein the nitrogen-vacancy defects are uniformly distributed through the synthetic single crystal CVD diamond material such that, when excited using a 514 nm laser excitation source of spot size equal to or less than 10 μ

m at room temperature using a 50 mW continuous wave laser, and mapped over an area equal to or greater than 50×

50 μ

m with a data interval less than 10 μ

m, there is a low point-to-point variation wherein the intensity area ratio of nitrogen vacancy photoluminescence peaks between regions of high photoluminescent intensity and regions of low photolominescent intensity is <

2×

for either the 575 nm photoluminescent peak (NV⁰) or the 637 nm photoluminescent peak (NV⁻

);

(iii) a variation in Raman intensity such that, when excited using a 514 nm laser excitation source (resulting in a Raman peak at 552.4 nm) of spot size equal to or less than 10 μ

m at room temperature using a 50 mW continuous wave laser, and mapped over an area equal to or greater than 50×

50 μ

m with a data interval less than 10 μ

m, there is a low point-to-point variation wherein the ratio of Raman peak areas between regions of low Raman intensity and high Raman intensity is <

1.25×

;

(iv) an as-grown nitrogen-vacancy defect (NV) concentration equal to or greater than 50 ppb as measured using 77K UV-visible absorption measurements, wherein, when excited using a 514 nm excitation source of spot size equal to or less than 10 μ

m at 77K using a 50 mW continuous wave laser, gives an intensity at 575 nm corresponding to NV⁰ greater than 120 times a Raman intensity at 552.4 nm, and/or an intensity at 637 nm corresponding to NV⁻

greater than 200 times the Raman intensity at 552.4 nm;

(v) a single substitutional nitrogen defect (N_s) concentration equal to or greater than 5 ppm, wherein the single substitutional nitrogen defects are uniformly distributed through the synthetic single crystal CVD diamond material such that by using a 1344 cm<sup>−

1</sup> infrared absorption feature and sampling an area greater than an area of 0.5 mm², the variation is lower than 80%, as deduced by dividing the standard deviation by the mean value;

(vi) a variation in red luminescence intensity, as defined by a standard deviation divided by a mean value, is less than 15%;

(vii) a mean standard deviation in neutral single substitutional nitrogen concentration of less than 80%; and

(viii) a colour intensity as measured using a histogram from a microscopy image with a mean gray value of greater than 50, wherein the colour intensity is uniform through the single crystal CVD synthetic diamond material such that the variation in gray colour, as characterised by the gray value standard deviation divided by the gray value mean, is less than 40%.

2. A single crystal CVD synthetic diamond material according to claim 1, wherein the single crystal CVD synthetic diamond material comprises two, three, four, five, six, seven or all eight of said characteristics.

3. A single crystal CVD synthetic diamond material according to claim 1, wherein the total nitrogen concentration, when mapped by secondary ion mass spectrometry (SIMS) over an area equal to or greater than 50×

50 μ

m with an analysis area defined as 10 μ

m or less, possesses a point-to-point variation of less than 25%, 20%, 15%, 10%, 5%, 3%, or 1% of an average nitrogen concentration value.

4. A single crystal CVD synthetic diamond material according to claim 1, wherein the luminescence from the nitrogen-vacancy defects, when mapped over an area equal to or greater than 50×

50 μ

m with an analysis area defined as 10 μ

m or less, possesses a point-to-point variation such that the intensity ratio between regions of high PL intensity and regions of low PL intensity is less than 1.8, 1.6, 1.4, or 1.2.

5. A single crystal CVD synthetic diamond material according to claim 1, wherein the NV⁰ luminescence at 575 nm is greater than 140, 160, or 180 times the Raman intensity at 552.4 nm, and/or the NV⁻

luminescence at 637 nm is greater than 220, 240, or 260 times the Raman intensity at 552.4 nm;

6. A single crystal CVD synthetic diamond material according to claim 1, the single substitutional nitrogen defects are uniformly distributed through the synthetic single crystal CVD diamond material such that by using the 1344 cm⁻

1 infrared absorption feature from the single substitutional nitrogen defects and sampling an area greater than an area of 0.5 mm² the variation is lower than 60%, 40%, 20%, 10% as deduced by dividing the standard deviation by the mean.

7. A single crystal CVD synthetic diamond material according to claim 1, wherein the variation in red luminescence is less than 10%, 8%, 6%, or 4%.

8. A single crystal CVD synthetic diamond material according to claim 1, wherein the mean standard deviation in neutral single substitutional nitrogen concentration is less than 60%, 40%, 20%, or 10%.

9. A single crystal CVD synthetic diamond material according to claim 1, wherein the colour intensity, when imaged over volume equal to or greater than 200×

200×

200 μ

m, possesses a point-to-point variation of less than 30%, 20%, 10%, or 5% of an average colour intensity, as defined by the gray value standard deviation divided by the gray value mean.

10. A single crystal CVD synthetic diamond material according to claim 1, wherein the total nitrogen concentration is equal to or greater than 7 ppm, 10 ppm, 15 ppm, 20 ppm, 30 ppm, 50 ppm, 75 ppm, 100 ppm, 150 ppm, 200 ppm, or 300 ppm.

11. A single crystal CVD synthetic diamond material according to claim 1, wherein the single substitutional nitrogen defect (N_s) concentration is equal to or greater than 7 ppm, 10 ppm, 15 ppm, 20 ppm, 30 ppm, 50 ppm, 75 ppm, 100 ppm, 150 ppm, 200 ppm, or 300 ppm.

12. A single crystal CVD synthetic diamond material according to claim 1, wherein the as-grown nitrogen-vacancy defect (NV⁻

) concentration is equal to or greater than 120 ppb, 140 ppb, 160 ppb, 180 ppb, 200 ppb, 250 ppb, 300 ppb, 400 ppb, 500 ppb, 1000 ppb, or 5000 ppb.

13. A single crystal CVD synthetic diamond material according to claim 1, having a concentration of silicon equal to or less than 1×

10¹⁵ atoms cm<sup>−

3</sup>.

14. A single crystal CVD synthetic diamond material according to claim 1, wherein the single crystal CVD synthetic diamond material has a longest dimensions equal to or greater than 200 μ

m, 500 μ

m, 1 mm, 1.5 mm, 2.0 mm, 3.0 mm, or 5.0 mm.

15. A single crystal CVD synthetic diamond material according to claim 1, having a volume equal to or greater than 0.01 mm³, 0.05 mm³, 0.1 mm³, 0.5 mm³, 1.0 mm³, 3.0 mm³, 6.0 mm³, 9.0 mm³, or 15.0 mm³ though which said one or more characteristics hold true.

16. A single crystal CVD synthetic diamond material according to claim 1, wherein the single crystal CVD synthetic diamond material is in the form of a layer having a thickness less than 200 μ

m, 100 μ

m, 50 μ

m, 20 μ

m, 10 μ

m, 5 μ

m, 2 μ

m, or 1 μ

m.

17. A single crystal CVD synthetic diamond material according to claim 1, wherein the single crystal CVD synthetic diamond material is in the form of a layer having a thickness greater than 200 μ

m, 500 μ

m, 1 mm, 1.5 mm, 2.0 mm, 3.0 mm, or 5.0 mm.

18. A single crystal CVD synthetic diamond material according to claim 1, having a dislocation bundle density equal to or less than:

10⁶ dislocations cm<sup>−

2</sup>;

10⁴ dislocations cm<sup>−

2</sup>;

3×

10³ dislocations cm<sup>−

2</sup>;

10³ dislocations cm<sup>−

2</sup>;

10² dislocations cm<sup>−

2</sup>;

or 10 dislocations cm<sup>−

2</sup>.

19. A single crystal CVD synthetic diamond material according to claim 1, having a birefringence equal to or less than 5×

10<sup>−

5</sup>, 1×

10<sup>−

5</sup>, 5×

10<sup>−

6</sup>, or 1×

10<sup>−

6</sup>.

20. A single crystal CVD synthetic diamond material according to claim 1, which has been annealed and/or irradiated.

21. A single crystal CVD synthetic diamond material according to claim 1, wherein the single crystal CVD synthetic diamond material has one or more of the following colours:

pink, yellow, green, orange, red, purple.

22-31. -31. (canceled)