Polycrystalline group III metal nitride with getter and method of making
View Patent ↗A gettered polycrystalline group III metal nitride is formed by heating a group III metal with an added getter in a nitrogen-containing gas. Most of the residual oxygen in the gettered polycrystalline nitride is chemically bound by the getter. The gettered polycrystalline group III metal nitride is useful as a raw material for ammonothermal growth of bulk group III nitride crystals.
1. A polycrystalline gallium-containing group III metal nitride material, comprising:
a plurality of grains of a crystalline gallium-containing group III metal nitride;
the plurality of grains having an average grain size in a range of from about 10 nanometers to about 1 millimeter and defining a plurality of grain boundaries; and
the crystalline gallium-containing group III metal nitride having:
an atomic fraction of a gallium-containing group III metal in a range of from about 0.49 to about 0.55, the metal being selected from at least one of aluminum, indium, and gallium; and
an oxygen content in the form of a gallium-containing group III metal oxide or a substitutional impurity within the crystalline gallium-containing group III metal nitride less than about 10 parts per million (ppm); and
a plurality of inclusions within at least one of the plurality of grain boundaries and the plurality of grains, the plurality of inclusions comprising a getter, the getter constituting a distinct phase from the crystalline gallium-containing group III metal nitride and being incorporated into the polycrystalline gallium-containing group III metal nitride material at a level greater than about 200 parts per million.
2. The material as defined in claim 1 , wherein the crystalline gallium-containing group III metal nitride has a porosity in volume fraction in a range of from about 0.1 percent to about 30 percent by volume; and an apparent density in a range of from about 70 percent to about 99.8 percent of a theoretical density value.
3. The material as defined in claim 1 , wherein the getter comprises a metal.
4. The material as defined in claim 1 , wherein the getter comprises at least one of alkaline earth metals, scandium, titanium, vanadium, chromium, yttrium, zirconium, niobium, the rare earth metals, hafnium, tantalum, tungsten, a nitride of any of the foregoing, and a halide of any of the foregoing.
5. The material as defined in claim 1 , wherein the getter is present at a level greater than about 0.1% by weight.
6. The material as defined in claim 1 , wherein the oxygen content present as a gallium-containing group III metal oxide or as a substitutional impurity within the crystalline gallium-containing group III metal nitride is less than about 3 parts per million (ppm).
7. The material as defined in claim 1 , wherein the oxygen content present as a gallium-containing group III metal oxide or as a substitutional impurity within the crystalline gallium-containing group III metal is less than about 1 part per million (ppm).
8. The material as defined in claim 1 , wherein the plurality of grains is characterized by a density from about 100 per cubic centimeter to about 10,000 per cubic centimeter.
9. The material as defined in claim 1 , wherein the polycrystalline gallium-containing group III metal nitride material has a porosity from about 0.1 percent to about 10 percent by volume.
10. The material as defined in claim 1 , wherein the polycrystalline gallium-containing group III metal nitride material has a porosity from about 10 percent to about 30 percent by volume.
11. The material as defined in claim 1 , wherein each of the plurality of grains is characterized by an average grain diameter in a range of from about 1 millimeter to about 10 micrometers.
12. The material as defined in claim 1 , wherein the plurality of grains is characterized by an average grain diameter greater than about 1.0 micrometer.
13. The material as defined in claim 1 , wherein the polycrystalline gallium-containing group III metal nitride material is characterized by an apparent density in a range of from about 85 percent to about 95 percent of a theoretical value.
14. The material as defined in claim 1 , wherein the atomic fraction of the gallium-containing group III metal in the crystalline gallium-containing group III metal nitride is in a range of from about 0.50 to about 0.51.
15. The material as defined in claim 1 , wherein the crystalline gallium-containing group III metal nitride comprises one or more dopants to provide one or more of an n-type material, a p-type material, or a semi-insulating material.
16. The material as defined in claim 15 , wherein the one or more of an n-type material, a p-type material, or a semi-insulating material is characterized by a dopant concentration in a range of from about 10 21 atoms per cubic centimeters to about 10 16 atoms per cubic centimeters.
17. The material as defined in claim 1 , wherein the polycrystalline gallium-containing group III metal nitride material has an inter-grain bend strength greater than about 20 MegaPascal.
18. The material as defined in claim 1 , wherein the plurality of inclusions comprise a material selected from a metal, a metal nitride, a metal halide, a metal oxynitride, a metal oxyhalide, a metal oxide, and a combination of any of the foregoing.