Group III Nitride Crystal Growth via Low-Dislocation Substrate
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Solution Overview
Problem
Existing liquid-phase techniques for growing bulk group III nitride crystals face challenges such as cracking due to high dislocation densities in substrates and crystals, limiting the production of bulk crystal substrates.
Innovation Solution
A method involving a substrate with a low average density of threading dislocations (5×10^6 cm^-2 or less) for homoepitaxial growth of group III nitride crystals, using a nitrogen-containing gas dissolved in a group III metal-containing solvent, to minimize cracking and enable bulk crystal growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If liquid-phase technique is used to grow group III nitride crystal, then environmental protection is improved (toxic gases are not employed), but cracking occurs in substrate and grown crystal due to high dislocation density
Solution Approach 1:
The substrate is prepared in advance through a specific process that reduces threading dislocation density to 5×10^6 cm^-2 or less before the actual crystal growth. This preliminary preparation prevents cracking during the growth process by ensuring the substrate has sufficient crystalline quality to support the grown crystal without cracking.
Solution Approach 2:
The invention controls and optimizes the dislocation density parameter of the substrate to 5×10^6 cm^-2 or less. By changing this critical parameter through controlled substrate preparation, the cracking problem is resolved while maintaining the environmental benefits of liquid-phase growth.
2Quantity of substance
If high-pressure solution growth method is used, then bulk crystal can be grown, but manufacturing cost increases due to high pressure (1 GPa) and high temperature (1500° C.) conditions
Solution Approach 1:
The invention changes the growth parameters from extreme conditions (1 GPa, 1500° C.) to more moderate conditions (10 MPa, 800-1000° C.). This parameter optimization enables bulk crystal growth while significantly reducing manufacturing costs and equipment requirements.
Solution Approach 2:
The invention uses a disposable substrate with controlled dislocation density that can be easily replaced, rather than requiring expensive, complex high-pressure growth equipment. This approach reduces manufacturing cost while still enabling bulk crystal production.
3Area of stationary object
If platelike seed crystal with large diametric span is used, then bulk crystal growth is enabled, but cracking occurs in substrate and grown crystal
Solution Approach 1:
The substrate is prepared in advance with controlled dislocation density (5×10^6 cm^-2 or less) before growth. This preliminary quality control enables large-area substrates to be used without cracking, as the low dislocation density prevents stress concentration that would otherwise cause cracking in large structures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces cracking in substrates and grown crystals, allowing for the production of bulk group III nitride crystals with controlled dislocation densities, enhancing the feasibility of bulk crystal growth.
Implementation Method 1
a solution in which a nitrogen-containing gas is dissolved into a group III metal-containing solvent
Implementation Method 2
a step of bringing into contact with the substrate principal face a solution in which a nitrogen-containing gas is dissolved into a group III metal-containing solvent, to grow group III nitride crystal onto the principal face
Data Source
AI summary
Affords group III nitride crystal growth methods enabling crystal to be grown in bulk by a liquid-phase technique. One such method of growing group III nitride crystal from solution is provided with: a step of preparing a substrate having a principal face and including at least on its principal-face side a group III nitride seed crystal having the same chemical composition as the group III nitride crystal, and whose average density of threading dislocations along the principal face being 5×106 cm−2 or less; and a step of bringing into contact with the principal face of the substrate a solution in which a nitrogen-containing gas is dissolved into a group III metal-containing solvent, to grow group III nitride crystal onto the principal face.