1. A composition, comprising:
a polycrystalline group III metal nitride material having a plurality of grains, the plurality of grains characterized by a columnar structure;
one or more of the grains having an average grain size in a range of from about 10 nanometers to about 1 millimeter;
an atomic fraction of a group III metal in the group III metal nitride in a range of from about 0.49 to about 0.55, the metal in the group III metal nitride being selected from at least aluminum, indium, or gallium; and
an oxygen content in the group III metal nitride material provided as a group III metal oxide or as a substitutional impurity within a group III metal nitride is less than about 10 parts per million (ppm).
2. The composition defined in claim 1, wherein the group III metal comprises gallium, the group III metal nitride comprises gallium nitride, and the group III metal oxide comprises Ga2O3.
3. The composition defined in claim 1, wherein the polycrystalline group III nitride has a porosity in volume fraction in a range of from about 0.1 percent to about 30 percent characterizing the metal nitride material; and
an apparent density in a range of from about 70 percent to about 99.8 percent of a theoretical density value corresponding to the metal nitride.
4. The composition as defined in claim 1, further comprising a getter, at a level greater than about 200 parts per million.
5. The composition as defined in claim 4, wherein the getter comprises a metal.
6. The composition as defined in claim 4, wherein the getter comprises at least one of alkaline earth metals, scandium, titanium, vanadium, chromium, yttrium, zirconium, niobium, the rare earth metals, hafnium, tantalum, and tungsten.
7. The composition as defined in claim 4, wherein the getter is present at a level greater than about 0.1%.
8. The composition as defined in claim 7, wherein the getter comprises a metal.
9. The composition as defined in claim 7, wherein the getter comprises at least one of alkaline earth metals, scandium, titanium, vanadium, chromium, yttrium, zirconium, niobium, the rare earth metals, hafnium, tantalum, and tungsten.
10. The composition as defined in claim 2, wherein the oxygen content present as Ga2O3 or as a substitutional impurity within gallium nitride is less than about 3 parts per million (ppm).
11. The composition as defined in claim 2, wherein the oxygen content as Ga2O3 or as a substitutional impurity within gallium nitride is less than about 1 part per million (ppm).
12. The composition as defined in claim 1, wherein the plurality of grains is characterized by an average number of grains in a range of from about 100 per cubic centimeter to about 10,000 per cubic centimeter.
13. The composition as defined in claim 1, wherein the porosity of the metal nitride in a volume fraction is in a range of from about 0.1 percent to about 10 percent.
14. The composition as defined in claim 1, wherein the porosity of the metal nitride in a volume fraction is in a range of from about 10 percent to about 30 percent.
15. The composition as defined in claim 1, further comprising an average grain diameter greater than about 1 millimeter.
16. The composition as defined in claim 1, further comprising an average grain diameter in a range of from about 1 millimeter to about 10 micrometers.
17. The composition as defined in claim 1, further comprising an average grain diameter greater than about 1.0 micrometer.
18. The composition as defined in claim 1, wherein the apparent density of the polycrystalline metal nitride is in a range of from about 85 percent to about 95 percent of the theoretical value.
19. The composition as defined in claim 1, wherein the atomic fraction of the metal in the metal nitride is in a range of from about 0.50 to about 0.51.
20. The composition as defined in claim 1, further comprising one or more dopants capable of producing one or more of n-type material, p-type material, or semi-insulating material.
21. The composition as defined in claim 20, further comprising a dopant concentration greater than about 1021 atoms per cubic centimeters.
22. The composition as defined in claim 21, wherein the dopant concentration is in a range of from about 1021 atoms per cubic centimeters to about 1016 atoms per cubic centimeters.
23. The composition as defined in claim 1, wherein the polycrystalline metal nitride has an inter-grain bend strength greater than about 20 MegaPascal.
24. The composition as defined in claim 1, wherein the polycrystalline metal nitride has an inter-grain bend strength that is in a range of from about 20 MegaPascal to about 90 MegaPascal.
25. The composition as defined in claim 1, wherein the polycrystalline metal nitride has an inter-grain bend strength greater than about 90 MegaPascal.
26. A method, comprising:
providing a group III metal in at least one crucible, the group III metal comprising at least one metal selected from at least aluminum, gallium, and indium;
providing a getter at a level of at least 100 ppm with respect to the group III metal, the getter being selected from at least alkaline earth metals, scandium, titanium, vanadium, chromium, yttrium, zirconium, niobium, rare earth metals, hafnium, tantalum, and tungsten;
providing the group III metal in the crucible and the getter into a chamber;
transferring a nitrogen-containing material into the chamber;
heating the chamber to a determined temperature;
pressurizing the chamber to a determined pressure;
processing the nitrogen-containing material with the group III metal in the chamber; and
forming a polycrystalline group III metal nitride in the at least the crucible that contained the group III metal.
27. The method as defined in claim 26, wherein the getter comprises at least one or more materials selected from calcium, strontium, barium, zirconium, hafnium, and tantalum.
28. The method of claim 26, wherein the getter is provided to the crucible together with the group III metal.
29. The method of claim 26, wherein the getter is at a level greater than 300 parts per million with respect to the group III metal.
30. The method of claim 29, wherein the getter is at a level greater than about 0.1% with respect to the group III metal.
31. The method of claim 30, wherein the getter is at a level greater than about 1% with respect to the group III metal.
32. The method of claim 26, further comprising supplying a dopant or a dopant precursor.
33. The method of claim 26, further comprising transferring hydrogen halide to the chamber so as to mix with the nitrogen containing material.
34. The method of claim 26, further comprising contacting the group III metal with one or more wetting agents, wherein the wetting agent comprises bismuth, germanium, tin, lead, antimony, tellurium, polonium, or a combination thereof.
35. The method of claim 26, further comprising:
cooling the chamber;
removing the polycrystalline group III nitride from the chamber;
providing the polycrystalline group III nitride to an autoclave or a capsule along with ammonia and a mineralizer; and
processing the polycrystalline group III nitride in supercritical ammonia at a temperature greater than 400 degrees Celsius and a pressure greater than 0.2 GPa.
36. The method of claim 35, wherein the mineralizer comprises at least one of an alkali metal and an alkaline earth metal.
37. The method of claim 36, further comprising providing an additional getter comprising at least one of Be, Mg, Ca, Sr, Ba, Sc. Y, a rare earth metal, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, or W.
38. The method of claim 35, wherein the mineralizer comprises at least one of a chloride and a fluoride.
39. The method of claim 38, further comprising providing an additional getter comprising at least one of Sc, Cr, Zr, Nb, Hf, Ta, or W.
40. The method of claim 26, further comprising:
cooling the chamber;
removing the polycrystalline group III nitride from the chamber;
providing the polycrystalline group III nitride to a furnace along with a flux; and
processing the polycrystalline group III nitride in a molten flux at a temperature greater than 400 degrees Celsius and a pressure greater than 1 atmosphere.
41. A method of forming a group III metal nitride containing substrate, comprising:
providing a group III metal as a source material, the group III metal comprising at least one metal selected from at least aluminum, gallium, and indium;
providing a getter at a level of at least 100 ppm with respect to the group III metal source material;
providing the group III metal source material and the getter into a chamber;
transferring a nitrogen-containing material into the chamber;
heating the chamber to a determined temperature;
pressurizing the chamber to a determined pressure;
processing the nitrogen-containing material with the group III metal source material in the chamber;
forming a crystalline group III metal nitride characterized by a wurtzite structure substantially free from any cubic entities and an optical absorption coefficient of about 2 cm\u22121 and less at wavelengths between about 385 nanometers and about 750 nanometers.
42. A gallium nitride containing crystal comprising:
a crystalline substrate member having a length greater than about 5 millimeters;
a substantially wurtzite structure characterized to be substantially free of other crystal structures, the other structures being less than about 1% in volume in reference to a volume of the substantially wurtzite structure;
an impurity concentration greater than about 1015 cm\u22121 of at least one of Li, Na, K, Rb, Cs, Mg, Ca, F, and Cl; and
an optical absorption coefficient of about 2 cm\u22121 and less at wavelengths between about 385 nanometers and about 750 nanometers.
43. The gallium nitride crystal of claim 42 wherein the other structures are less than about 0.5% in volume.
44. The gallium nitride crystal of claim 42 wherein the other structures are less than about 0.1% in volume.
45. The gallium nitride crystal of claim 42, wherein the crystalline substrate member is an n-type semiconductor, characterized by a carrier concentration n between about 1016 cm\u22123 and 1020 cm\u22123 and a carrier mobility \u03b7, in units of centimeters squared per volt-second, such that the logarithm to the base 10 of \u03b7 is greater than about \u22120.018557 n3+1.0671 n2-20.599 n+135.49.
46. The gallium nitride crystal of claim 42, wherein the crystalline substrate member is a p-type semiconductor, characterized by a carrier concentration n between about 1016 cm\u22123 and 1020 cm\u22123 and a carrier mobility \u03b7, in units of centimeters squared per volt-second, such that the logarithm to the base 10 of \u03b7 is greater than about \u22120.6546 n+12.809.
47. The gallium nitride crystal of claim 42, wherein the crystalline substrate member is semi-insulating, with a resistivity greater than 107 \u03a9-cm.
48. The gallium nitride crystal of claim 42, characterized by an impurity concentration greater than 1015 cm\u22121 of at least one of Li, Na, K, Rb, and Cs and an impurity concentration greater than 1014 cm\u22121 of at least one of Be, Mg, Ca, Sr, Ba, Sc, Y, a rare earth element, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, or W.
49. The gallium nitride crystal of claim 42, characterized by an impurity concentration greater than 1015 cm\u22121 of at least one of F and Cl and an impurity concentration greater than 1014 cm\u22121 of at least one of Sc, Cr, Zr, Nb, Hf, Ta, or W.
50. The crystal of claim 42 wherein the other crystal structures comprise a cubic structure.
51. The crystal structure of claim 42 wherein the crystalline substrate member comprises gallium nitride.
52. The crystal structure of claim 42 wherein the crystalline substrate member comprises a gallium species and a nitrogen species.
53. The crystal structure of claim 42 wherein the substrate member having a thickness of greater than about 1 millimeter.
54. The crystal structure of claim 42 wherein the length is greater than about 20 millimeters.
55. The crystal structure of claim 42 wherein the length is greater than about 50 millimeters.
56. The crystalline structure of claim 42 wherein the length is greater than about 100 millimeters.
57. The crystalline structure of claim 42 wherein the crystalline substrate member is characterized by crystallographic radius of curvature of greater than 100 meters.
58. The crystalline structure of claim 42 wherein the crystalline substrate member is characterized by crystallographic radius of curvature of greater than 1000 meters.
59. The crystalline structure of claim 42 wherein the crystalline substrate member is characterized by an infinite crystallographic radius of curvature.
60. The crystalline structure of claim 42 wherein the crystalline substrate member has a root-mean-square surface roughness of 1 nanometer and less.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A mould apparatus for securing a stent onto a balloon of a stent delivery system, the stent delivery system balloon having a stent receiving portion intermediate a proximal balloon portion and a distal balloon portion, the stent mounted on the stent receiving portion, the mould apparatus comprising:
a mould body being split along its longitudinal axis to provide a top cavity portion and a bottom cavity portion which in use, are positioned together over the stent and stent delivery system with the top cavity portion and bottom cavity portion forming a finished profile for the delivery system the top and bottom cavity portions having a first section having a first diameter and a single second section with a second diameter, the second diameter smaller than the first diameter wherein the finished profile for the delivery system has a single stent section for receiving the stent mounted on the stent receiving portion and at least one balloon pillow section next to the single stent section for receiving the proximal balloon portion, the balloon pillow section having the first diameter and the stent section having the second diameter;
at least one mould holder to facilitate clamping of the mould cavity portions and;
a hot block coupled to the mould for providing heat to the first and second sections of the mould cavities.
2. An apparatus of claim 1 wherein the finished profile for the stent delivery system has a tapered profile.
3. An apparatus of claim 1 wherein the finished profile for the stent delivery system has a second balloon pillow section for receiving the distal balloon portion of the stent delivery system.