DIAMOND MATERIAL

• US 20120051996A1
• Filed: 07/22/2009
• Published: 03/01/2012
• Est. Priority Date: 07/23/2008
• Status: Active Grant

• Current Assignee: Element Six Technologies US Corporation (Anglo American PLC)
• Original Assignee: Daniel James Twitchen, Geoffrey Alan Scarsbrook, Matthew Lee Markham
• Inventors: Scarsbrook, Geoffrey Alan, Twitchen, Daniel James, Markham, Matthew Lee
• Granted Patent: US 9,317,811 B2
• Time in Patent Office: Days
• US Class Current: 423/446
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: C30B 25/105 by irradiation or electric discharge
• CPC Class Codes: C30B 25/20 the substrate being of the same materials as the epitaxial layer
• CPC Class Codes: C30B 29/04 Diamond
• CPC Class Codes: C30B 31/22 by ion-implantation
• CPC Class Codes: C30B 33/02 Heat treatment C30B33/04, C30B33/06 take precedence
• CPC Class Codes: G06N 10/00 Quantum computing, i.e. information processing based on quantum-mechanical phenomena

Abstract

Single crystal diamond having a high chemical purity i.e. a low nitrogen content and a high isotopic purity i.e. a low ¹³C content, methods for producing the same and a solid state system comprising such single crystal diamond are described.

Claims

1. A method of preparing diamond material of high chemical purity and high isotopic purity comprising;

activating and/or dissociating providing a source gas mixture and a solid carbon source to form gaseous carbon species, the source gas mixture comprising high purity gases, wherein the concentration of nitrogen in the source gas mixture is about 300 ppb or less,

the solid carbon source comprising ¹²C in an amount of at least about 99% of the total C content of the source, wherein the solid carbon source has a low nitrogen impurity content;

and

growing a homoepitaxial diamond layer on the surface of a substrate from the gaseous carbon species, the substrate surface being substantially free of crystal defects.

2. A method according to claim 1, wherein the solid carbon source is diamond.

3. A method according to claim 1, wherein the solid carbon source provides about 80% or more of the gaseous carbon species.

5. A method according to claim 1, wherein at least one of the following conditions is satisfied:

(i) the temperature of the substrate is in the range from about 800°

C. to about 1000°

C.; and

(ii) oxygen is added to the source gas in an amount of between about 0.5% and about 5% by volume, measured as O₂ equivalent, of the total source gas mixture.

19. A method according to claim 5, wherein at least one isolated NV centre is formed in the diamond material.

20. A method according to claim 19, wherein the NV centre is formed by nitrogen ion implantation, nitrogen atom implantation or nitrogen-containing ion implantation.

21. A method according to claim 19, wherein the NV centre is grown into the diamond material.

22. A method according to claim 5, comprising a further step of annealing at a temperature in the range from about 600°

C. to about 900°

C. for a time period in the range from about 0.1 hours to about 16 hours.

23. A method according to claim 5, comprising a further step of annealing at a temperature of about 1000°

C. or more for a time period in the range from about 0.1 hours to about 16 hours.

25. A method according to claim 19, wherein at least one NV centre is separated from other elements with magnetic spin by about 0.02 μ

m or more.

4. (canceled)

6-7. -7. (canceled)

8. A method of preparing a diamond material of high chemical purity and high isotopic purity comprising:

dissociating a source gas mixture, the source gas mixture comprising high purity gases and a carbon source gas, wherein the high purity gases contribute about 300 ppb or less to the total nitrogen levels in the source gas mixture and the carbon source gas comprises ¹²C in an amount of at least 99% of the total C content of the carbon source gas and contains nitrogen impurities in amount of about 20 ppm or less;

growing a homoepitaxial diamond layer on the surface of a diamond substrate from the dissociated source gas mixture, the diamond surface being substantially free of crystal defects, wherein at least one of the following conditions is satisfied;

(a) the temperature of the substrate is in the range from about 800°

C. to about 1000°

C.; and

(b) oxygen is added to the source gas in an amount of between about 0.5% and about 5% by volume, measured as O₂ equivalent, of the total source gas mixture.

11. A method according to claim 8, wherein the carbon source gas comprises less than about 5 ppm nitrogen impurities.

13. A method according to claim 8, comprising a further step of processing a surface of the diamond material to form a surface which is substantially free of crystal defects.

18. A method according to claim 13, comprising growing a further layer of host material over the processed surface of the host material, wherein the further layer has a thickness of about 100 μ

m or less.

9-10. -10. (canceled)

12. (canceled)

14-17. -17. (canceled)

24. (canceled)

26-27. -27. (canceled)

28. A synthetic diamond material layer, wherein the diamond layer has a total nitrogen concentration of about 5 ppb or less and a total concentration of ¹³C of about 0.9% or less.

35. Synthetic diamond material according to claim 28, wherein the concentration of paramagnetic defects is about 1 ppm or less.

42. A solid state system according to claim 39, wherein the host material is a synthetic diamond material layer as defined in claim 28.

29-34. -34. (canceled)

36-38. -38. (canceled)

39. A solid state system comprising a host material and a quantum spin defect, said quantum spin defect having a T₂ at room temperature of about 500 μ

s or more.

41. A solid state system according to claim 39, wherein the stability of the transition from the m_s=±

1 to the m_s=0 state for the quantum spin defect is such that the FWHM of the peak of a histogram of the number of photons having a particular frequency versus the frequency of the photon is about 500 MHz or less.

45. A system according to claim 39, wherein the quantum spin defect is positioned within about 100 μ

m of a surface of the diamond.

47. A system according to claim 39, wherein the surface of the host material is terminated with ¹⁶O.

51. A system according to claim 39, wherein the host material is CVD diamond which has a high chemical purity and has a concentration of neutral single substitutional nitrogen of about 10 ppb or less.

52. A system according to claim 51, wherein the CVD diamond has a high isotopic purity, wherein the fraction, expressed as a percentage of the total C atoms that are ¹²C atoms in the CVD diamond is about 99% or more.

54. A system according to claim 39, wherein the quantum spin defect is an NV centre.

61. A system according to claim 39, which is a quantum repeater, a quantum cryptography device, a quantum computing device, a spintronic device or a magnetometer.

40. (canceled)

43-44. -44. (canceled)

46. (canceled)

48-50. -50. (canceled)

53. (canceled)

55-60. -60. (canceled)