Molten-salt-based growth of group III nitrides

• US 7,435,297 B1
• Filed: 04/08/2005
• Issued: 10/14/2008
• Est. Priority Date: 04/08/2004
• Status: Active Grant

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Kerley, Thomas M., Waldrip, Karen E., Tsao, Jeffrey Y.
• Primary Examiner(s): Kunemund; Robert M.
• Assistant Examiner(s): RAO, G NAGESH
• Application Number:
  US11/102,357
• Time in Patent Office: 1,285 Days
• Field of Search: 117/84, 117/89, 117/105, 117/108, 117/952
• US Class Current: 117/89
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 9/12 Salt solvents, e.g. flux growth
• CPC Class Codes: C30B 9/14 by electrolysis

Abstract

A method for growing Group III nitride materials using a molten halide salt as a solvent to solubilize the Group-III ions and nitride ions that react to form the Group III nitride material. The concentration of at least one of the nitride ion or Group III cation is determined by electrochemical generation of the ions.

Claims

1. A method for growing Group III nitride crystalline material comprising:

forming a nitride ion by reducing a nitrogen gas;

forming a Group III cation by oxidizing a liquid Group III metal; and

combining the Group III cation and the nitride ion to form a Group III nitride.

2. The method of claim 1, further comprising performing in a molten salt solvent the steps of forming the nitride ion, forming the Group III cation, and combining the Group III cation and the nitride ion.

3. The method of claim 2, further comprising dissolving a Group III nitride in the molten salt solvent.

4. The method of claim 2, wherein the molten salt solvent is selected from the group consisting of LiF, NaF, KF, CsF, LiCl, NaCl, KCl, CsCl, LiBr, NaBr, KBr, CsBr, LiI, NaI, KI, and CsI.

5. The method of claim 2, wherein the molten salt solvent comprises LiCl and KCl.

6. The method of claim 2, wherein the molten salt solvent comprises a nitride ion primer.

7. The method of claim 6, wherein the nitride ion primer is selected from the group consisting of Li₃N, Na₃N, K₃N, and Ca₃N₂.

8. The method of claim 1, wherein the step of forming the nitride ion by reducing the nitrogen gas is performed by applying a reducing electrical potential.

9. The method of claim 1, wherein the step of forming the Group III ion by oxidizing the liquid Group III metal is performed by applying an oxidizing electrical potential.

10. The method of claim 1, wherein the Group III cation is selected from the group consisting of a B ion, an Al ion, a Ga ion, and an In ion.

11. A method for growing Group III nitride crystalline material comprising:

dissolving a nitride ion precursor to produce a nitride ion in a molten salt solvent;

forming a Group III cation by oxidizing a liquid Group III metal in the molten salt solvent; and

combining the Group III cation and the nitride ion to form a Group III nitride.

12. The method of claim 11, wherein the molten salt solvent is selected from the group consisting of LiF, NaF, KF, CsF, LiCl, NaCl, KCl, CsCl, LiBr, NaBr, KBr, CsBr, LiI, NaI, KI, and CsI.

13. The method of claim 11, wherein the molten salt solvent comprises LiCl and KCl.

14. The method of claim 11, wherein the step of forming the Group III cation by oxidizing the liquid Group III metal is performed by applying an oxidizing electrical potential.

15. The method of claim 11, wherein the Group III cation is selected from the group consisting of a B ion, an Al ion, a Ga ion, and an In ion.

16. The method of claim 11, further comprising cooling the nitride ion precursor prior to the step of dissolving the nitride ion precursor in the molten salt solvent.

17. A method for growing Group III nitride crystalline material comprising:

dissolving a Group III ion precursor to form a Group III cation in a molten salt solvent;

forming a nitride ion by electrochemically reducing a nitrogen gas in the molten salt solvent; and

combining the Group III cation and the nitride ion to form a Group III nitride.

18. The method of claim 17, wherein the molten salt solvent is selected from the group consisting of LiF, NaF, KF, CsF, LiCl, NaCl, KCl, CsCl, LiBr, NaBr, KBr, CsBr, LiI, NaI, KI, and CsI.

19. The method of claim 17, further comprising cooling the Group III ion precursor prior to the step of dissolving the Group III ion precursor in the molten salt solvent.

20. The method of claim 17, wherein the molten salt solvent comprises LiCl and KCl.

21. The method of claim 17, wherein the molten salt solvent comprises a nitride ion primer.

22. The method of claim 21, wherein the nitride ion primer is selected from the group consisting of Li₃N, Na₃N, K₃N, and Cd₃N₂.

23. The method of claim 17, wherein the step of forming the nitride ion by reducing the nitrogen gas is performed by applying a reducing electrical potential.

24. The method of claim 17, wherein the Group III cation is selected from the group consisting of a B ion, an Al ion, a Ga ion, and an In ion.

25. A method for growing Group III nitride crystalline material comprising:

dissolving a Group III ion precursor to form a Group III cation in a molten salt solvent;

dissolving a nitride ion precursor to form a nitride ion in the molten salt solvent;

forming an excess of a constituent ion by applying an electrochemical potential; and

combining the Group III cation and the nitride ion to form a Group III nitride.

26. The method of claim 25, wherein the constituent ion is a nitride ion formed by reducing a nitrogen gas.

27. The method of claim 25, wherein the constituent ion is a Group III cation formed by oxidizing a liquid Group III metal.

28. The method of claim 27, wherein the Group III cation is selected from the group consisting of a B ion, an Al ion, a Ga ion, and an In ion.

29. The method of claim 25, wherein the molten salt solvent is selected from the group consisting of LiF, NaF, KF, CsF, LiCl, NaCl, KCl, CsCl, LiBr, NaBr, KBr, CsBr, LiI, NaI, KI, and CsI.

30. The method of claim 25, wherein the molten salt solvent comprises LiCl and KCl.

31. The method of claim 25, further comprising cooling the Group III ion precursor prior to the step of dissolving the Group III ion precursor in the molten salt solvent.

32. The method of claim 25, further comprising cooling the nitride ion precursor prior to the step of dissolving the nitride ion precursor in the molten salt solvent.