# US 2014/0190403 A1 · Method for growing group iii-nitride crystals in supercritical ammonia using an autoclave > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0190403 A1 - Document ID: US20140190403A1 - Status: Published application - Kind: A1 - Application number: 14/206,558 - Filed: 2014-03-12 - Published: 2014-07-10 - Earliest claimed: 2007-11-30 - Assignees: Japan Science and Technology Agency; The Regents of the University of California - Applicants: Japan Science and Technology Agency; The Regents of the University of California - Inventors: Kenji Fujito; Tadao Hashimoto; Shuji Nakamura - Web page: https://patentgrep.com/patent/US20140190403A1 ## CPC - C30B 7/105: {using ammonia as solvent, i.e. ammonothermal processes} - C30B 7/10: by application of pressure, e.g. hydrothermal processes - C30B 29/403: {AIII-nitrides} - C30B 29/406: {Gallium nitride} - Y10T 117/1096: including pressurized crystallization means [e.g., hydrothermal] - C30B: SINGLE-CRYSTAL GROWTH (by using ultra-high pressure, e.g. for the formation of diamonds, B01J3/06); UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL (zone-refining of metals or alloys C22B); PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (casting of metals, casting of other substances by the same processes or devices B22D; working of plastics B29; modifying the physical structure of metals or alloys C21D, C22F); SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE (for producing semiconductor devices or parts thereof H10); APPARATUS THEREFOR - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A method of growing high-quality, group-III nitride, bulk single crystals. The group III-nitride bulk crystal is grown in an autoclave in supercritical ammonia using a source material or nutrient that is a group III-nitride polycrystals or group-III metal having a grain size of at least 10 microns or more and a seed crystal that is a group-III nitride single crystal. The group III-nitride polycrystals may be recycled from previous ammonothermal process after annealing in reducing gas at more then 600° C. The autoclave may include an internal chamber that is filled with ammonia, wherein the ammonia is released from the internal chamber into the autoclave when the ammonia attains a supercritical state after the heating of the autoclave, such that convection of the supercritical ammonia transfers source materials and deposits the transferred source materials onto seed crystals, but undissolved particles of the source materials are prevented from being transferred and deposited on the seed crystals. ## Claims ### Claim 1 An apparatus for growing group-III nitride crystals, comprising: (a) an autoclave; and (b) an internal chamber placed within the autoclave, wherein the internal chamber is filled with source materials, group-III nitride seed crystals and ammonia, the autoclave's temperature is raised, and the ammonia is released from the internal chamber into the autoclave when the ammonia attains a supercritical state, such that convection of the supercritical ammonia transfers the source materials and deposits the transferred source materials onto the group-III nitride seed crystals. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the ammonia is released from the internal chamber into the autoclave to balance the pressure between inside and outside of the internal chamber. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the internal chamber is equipped with a valve that is mechanically opened when the internal chamber is inside the autoclave. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the internal chamber is equipped with a pressure-releasing mechanism that is activated at a high pressure. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein the internal chamber is equipped with a pressure-releasing mechanism that is activated at a low temperature. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the internal chamber is equipped with a pressure-releasing mechanism comprising a rupture disk that ruptures at a high pressure. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the internal chamber is equipped with a pressure-releasing mechanism comprising a fitting seal that leaks at a high pressure. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the internal chamber is equipped with a pressure-releasing mechanism comprising a metal seal that melts at a low temperature. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein the source materials are held in a mesh basket and the mesh basket is made of Ni or Ni-based alloy that contains at least 30% of Ni. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the source materials have a grain size of at least 10 microns. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein the source materials are group-III nitride polycrystals. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein the source materials are a group-III metal. ### Claim 13 (depends on 1) The apparatus of claim 1, wherein the source materials are a mixture of group-III metal and group-III nitride polycrystals. ### Claim 14 (depends on 1) The apparatus of claim 1, wherein part or all of the source materials are prepared by a recycling process for a nutrient used in a previous ammonothermal process or fragments of the group III-nitride crystals grown in the previous ammonothermal process ### Claim 15 (depends on 14) The apparatus of claim 14, wherein the nutrients or the fragments are annealed in the recycling process at more than 600° C. in a reducing environment. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the reducing environment contains hydrogen or ammonia. ### Claim 17 (depends on 1) The apparatus of claim 1, wherein undissolved particles of the source materials are prevented from being transferred and deposited on the group-III nitride seed crystals during the convection of the supercritical ammonia.