Method and system for preparing polycrystalline group III metal nitride

1. A method using a reactor, comprising:

placing a group III metal inside a source chamber;

flowing a halogen-containing gas over the group III metal to form a group III metal halide;

contacting said group III metal halide with a nitrogen-containing gas in a deposition chamber containing a foil, said foil comprising at least one of Mo, W, Ta, Pd, Pt, Ir, or Re;

forming a polycrystalline group III nitride layer on said foil within said deposition chamber, wherein the polycrystalline group III nitride layer has a first surface that is in contact with said foil and a second surface that is opposite to the first surface, and the formed polycrystalline group III nitride layer is substantially free of pores that extend between the first surface and the second surface;

removing said polycrystalline group III nitride layer from said foil, wherein the first surface of the polycrystalline group III nitride layer has a root-mean-square roughness that is less than a root-mean-square roughness of the second surface; and

comminuting said polycrystalline group III nitride layer to form polycrystalline group III nitride chunks, wherein

said removing and said comminuting are performed in any order or simultaneously.

2. The method of claim 1 , wherein said foil comprises at least one of Mo or W.

3. A method of using a reactor, comprising:

placing a group III metal inside a source chamber, the source chamber being enclosed within an outer enclosure of the reactor;

flowing a halogen-containing gas through a first inlet line of the reactor and over the group III metal within the source chamber to form a group III metal halide and to transport the group III metal halide from the source chamber to a deposition chamber of the reactor through a transfer tube, wherein the deposition chamber is enclosed within the outer enclosure;

flowing a nitrogen-containing gas through a second inlet line to contact the group III metal halide in the deposition chamber;

flowing a purge gas through a third inlet line into a space between the outer enclosure, the source chamber and the deposition chamber;

forming a polycrystalline group III nitride layer on a deposition surface within the deposition chamber;

removing the polycrystalline group III nitride layer from the deposition surface; and

comminuting the polycrystalline group III nitride layer to form polycrystalline group III nitride chunks, wherein

the removing and the comminuting steps are performed in any order or simultaneously, wherein

at least one of a first joint coupling the source chamber to the transfer tube and a second joint coupling the transfer tube to the deposition chamber is non-leak-tight.

4. The method of claim 3 , further comprising using said polycrystalline group III nitride chunks as a nutrient for ammonothermal crystal growth to grow a group III nitride boule and preparing one or more group III nitride wafers from said group III nitride boule.

5. The method of claim 3 , wherein

the first inlet line is coupled to the source chamber by a non-leak-tight-joint,

the second inlet line is coupled to the deposition chamber by a non-leak-tight-joint, and

the flowing of the purge gas through the third inlet line and into the space between the outer enclosure, the source chamber and the deposition chamber is such that any gas leaking from the non-leak-tight-joints is entrained by the purge gas.

6. The method of claim 5 , wherein the reactor further comprises an intermediate enclosure configured between the outer enclosure, the source chamber and the deposition chamber, wherein the third inlet line is in fluid communication with the space between the outer enclosure and the intermediate enclosure.

7. The method of claim 3 , wherein at least one of the source chamber and the deposition chamber comprise a non-oxide-containing material, the non-oxide-containing material being selected from boron nitride, silicon carbide, graphite, molybdenum, tantalum, and tungsten, and combinations thereof.

8. The method of claim 3 , wherein the deposition surface comprises a foil comprising at least one of Mo, W, Ta, Pd, Pt, Ir, or Re.

9. The method of claim 3 , wherein at least one of the steps of placing the group III metal in the source chamber and removing the polycrystalline group III nitride layer from the deposition chamber is performed in a glove box without exposing the interior of the reactor to air.

10. The method of claim 1 , wherein the halogen-containing gas comprises one or more of HCl and Cl 2 .

11. The method of claim 1 , further comprising a dopant precursor into at least one of the source chamber and the deposition chamber.

12. The method of claim 11 , wherein the dopant precursor comprises at least one of SiH 4 , SiCl 4 , GeH 4 , GeCl 4 , H 2 O, or Mg(C 5 H 5 ) 2 .

13. The method of claim 1 , wherein at least the source chamber is baked to remove residual moisture or other contaminants prior to flowing the halogen-containing gas over the group III metal to form the group III metal halide.

14. The method of claim 1 , further comprising adjusting the flow rate of the halogen-containing gas and the flow rate of the nitrogen-containing gas to achieve an efficiency with which the group III metal atoms are converted from an elemental state in the source chamber to polycrystalline group III nitride on the foil in the deposition chamber that is greater than 75%.

15. The method of claim 1 , further comprising subjecting at least one surface of the formed polycrystalline group III nitride layer to one or more of scraping, scouring or scarifying.

16. The method of claim 1 , further comprising subjecting one or more surfaces of the polycrystalline group III nitride to one or more of jaw crushing, ball milling, attrition milling, sieving, oxidation in air or in dry oxygen, heating in aqueous base, washing, sonicating, or annealing in an inert, nitriding, or reducing atmosphere.

17. The method of claim 16 , wherein one or more of washing and sonicating is performed in one or more of organic solvents, acids, bases, hydrogen peroxide, o or other oxidizers.

18. The method of claim 3 , wherein the polycrystalline group III nitride layer has a first surface that is in contact with a foil disposed over the deposition surface and a second surface that is opposite to the first surface, and the formed polycrystalline group III nitride layer is substantially free of pores that extend between the first surface and the second surface.

19. The method of claim 18 , wherein the first surface of the polycrystalline group III nitride layer has a root-mean-square roughness that is less than a root-mean-square roughness of the second surface.

20. The method of claim 3 , wherein an intermediate enclosure is disposed between the outer enclosure, and the source chamber and the deposition chamber.

21. The method of claim 20 , wherein a path, along which the flowing of the purge gas through the third inlet line and into the space between the outer enclosure, the source chamber and the deposition chamber follows, comprises a space between the outer enclosure and the intermediate enclosure, a gap formed in the intermediate enclosure, and a space between the intermediate enclosure and the source chamber and the deposition chamber.