Process and apparatus for obtaining bulk monocrystalline gallium-containing nitride
First Claim
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1. A process for obtaining a bulk monocrystalline gallium-containing nitride in an autoclave having a gallium-containing feedstock in one zone, a seed in another zone and a supercritical solvent containing ions of alkali metals therein, said process comprising the steps of:
- dissolving the gallium-containing feedstock in the supercritical solvent to form a supercritical solution at a first temperature; and
crystallizing the bulk monocrystalline gallium-containing nitride from the supercritical solution on the seed at a second temperature higher than the first temperature at which the feedstock dissolves in the supercritical solvent.
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Abstract
The present invention refers to an ammonobasic method for preparing a gallium-containing nitride crystal, in which gallium-containing feedstock is crystallized on at least one crystallization seed in the presence of an alkali metal-containing component in a supercritical nitrogen-containing solvent. The method can provide monocrystalline gallium-containing nitride crystals having a very high quality.
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Citations
74 Claims
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1. A process for obtaining a bulk monocrystalline gallium-containing nitride in an autoclave having a gallium-containing feedstock in one zone, a seed in another zone and a supercritical solvent containing ions of alkali metals therein, said process comprising the steps of:
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dissolving the gallium-containing feedstock in the supercritical solvent to form a supercritical solution at a first temperature; and crystallizing the bulk monocrystalline gallium-containing nitride from the supercritical solution on the seed at a second temperature higher than the first temperature at which the feedstock dissolves in the supercritical solvent. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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- 24. A process for preparing a bulk monocrystalline gallium-containing nitride crystal in an autoclave, which comprises the steps of (i) providing a supercritical ammonia solution containing ions of alkali metal and gallium in a soluble form by introducing a gallium-containing feedstock to supercritical ammonia solvent containing ions of alkali metals, in which solubility of gallium-containing nitride shows a negative temperature coefficient in said supercritical ammonia solution, and (ii) crystallizing said gallium-containing nitride selectively on a crystallization seed from said supercritical ammonia solution by means of the negative temperature coefficient of solubility.
- 30. A process for controlling the recrystallization of a gallium-containing nitride in a supercritical ammonia solution which comprises the steps of (i) preparing a supercritical ammonia solution containing soluble gallium complex compounds formed by dissolving of gallium-containing nitride feedstock in the dissolution zone and (ii) controlling over-saturation of said supercritical ammonia solution with respect to the crystallization seed, while maintaining a temperature in the crystallization zone lower than that in the dissolution zone.
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36. A process for obtaining a gallium-containing nitride crystal, comprising the steps of:
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(i) providing a gallium-containing feedstock, an alkali metal-containing component, at least one crystallization seed and a nitrogen-containing solvent in at least one container; (ii) bringing the nitrogen-containing solvent into a supercritical state; (iii) at least partially dissolving the gallium-containing feedstock at a first temperature and at a first pressure; and (iv) crystallizing gallium-containing nitride on the crystallization seed at a second temperature and at a second pressure while the nitrogen-containing solvent is in the supercritical state; wherein at least one of the following criteria is fulfilled; (a) the second temperature is higher than the first temperature; and (b) the second pressure is lower than the first pressure. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
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65. A process for preparing a gallium-containing nitride crystal comprising the steps of:
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(i) providing a gallium-containing feedstock comprising at least two different components, an alkali metal-containing component, at least one crystallization seed and a nitrogen-containing solvent in a container having a dissolution zone and a crystallization zone, whereby the gallium-containing feedstock is provided in the dissolution zone and the at least one crystallization seed is provided in the crystallization zone; (ii) subsequently bringing the nitrogen-containing solvent into a supercritical state; (iii) subsequently partially dissolving the gallium-containing feedstock at a dissolution temperature and at a dissolution pressure in the dissolution zone, whereby a first component of the gallium-containing feedstock is substantially completely dissolved and a second component of the gallium-containing feedstock as well as the crystallization seed(s) remain substantially undissolved so that an undersaturated solution with respect to gallium-containing nitride is obtained; (iv) subsequently setting the conditions in the crystallization zone at a second temperature and at a second pressure so that over-saturation with respect to gallium-containing nitride is obtained and crystallization of gallium-containing nitride occurs on the at least one crystallization seed and setting the conditions in the dissolution zone at a first temperature and at a first pressure so that the second component of the gallium-containing feedstock is dissolved; wherein the second temperature is higher than the first temperature. - View Dependent Claims (66, 67, 68, 69, 70)
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71. A process for obtaining a gallium-containing nitride crystal, comprising the steps of:
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(i) providing a gallium-containing feedstock, at least one crystallization seed and a nitrogen-containing solvent in at least one container; (ii) bringing the nitrogen-containing solvent into a supercritical state; (iii) at least partially dissolving the gallium-containing feedstock at a first temperature and at a first pressure; and (iv) crystallizing gallium-containing nitride on the crystallization seed at a second temperature and at a second pressure while the nitrogen-containing solvent is in the supercritical state; wherein at least one of the following criteria is fulfilled; (a) the second temperature is higher than the first temperature; and (b) the second pressure is lower than the first pressure. - View Dependent Claims (72, 73, 74)
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Specification