Nitride Crystal Production via Granular Starting Material
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Solution Overview
Problem
The ammonothermal process for producing nitride crystals faces challenges in achieving high growth rates and efficient material utilization, particularly due to low dissolution rates of powdery nitride crystal starting materials and difficulties in controlling carrier concentration, leading to suboptimal crystal quality and increased production costs.
Innovation Solution
Controlling the bulk density and oxygen concentration of the nitride crystal starting material within specific ranges, along with optimizing the angle of repose, enables increased crystal growth rates and improved material utilization efficiency, allowing for the production of high-quality nitride crystals with desired carrier concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If powdery nitride crystal starting material is used in ammonothermal process, then crystal growth can be initiated, but dissolution rate is low and growth rate is limited
Solution Approach 1:
The invention changes the physical state parameter of the starting material from powdery to granular form, and optimizes particle size parameters (1-120 μm) to achieve both high dissolution rate and low aggregation, thereby improving crystal growth rate and material utilization efficiency simultaneously
Solution Approach 2:
The invention uses composite granular starting material composed of nitride crystal particles with specific size distribution and controlled oxygen concentration (10-500 ppm), creating a composite structure that enhances both dissolution performance and crystal growth efficiency
2Manufacturing precision
If oxygen concentration in starting material is not controlled, then production process is simpler, but carrier concentration control and crystal quality are poor
Solution Approach 1:
The invention performs preliminary control of oxygen concentration (10-500 ppm) in the granular starting material before the ammonothermal process, so that the desired carrier concentration is achieved during crystal growth without requiring complex post-growth doping processes
Solution Approach 2:
The invention precisely controls the oxygen concentration parameter in the starting material within 10-500 ppm range, which directly determines the carrier concentration in the grown crystal, enabling accurate electrical property control through compositional parameter optimization
3Loss of substance
If particle size of starting material is reduced to increase dissolution rate, then dissolution rate improves, but aggregation increases and growth rate decreases
Solution Approach 1:
The invention optimizes the particle size parameter to a specific range (1-120 μm) where the surface area to volume ratio provides sufficient dissolution rate while the particle size is large enough to prevent excessive aggregation, achieving balance between dissolution and growth rates
Solution Approach 2:
The invention creates a composite granular structure with controlled porosity and surface characteristics that enhances dissolution rate without promoting aggregation, allowing simultaneous improvement of both dissolution efficiency and crystal growth rate
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 results in efficient production of high-quality nitride crystals with enhanced growth rates and reduced production costs, enabling accurate oxygen doping and improved electroconductivity suitable for semiconductor applications.
Implementation Method 1
utilizing the dissolution-precipitation reaction of the starting material therein
Implementation Method 2
using a nitrogen-containing solvent such as ammonia or the like in a supercritical state and/or a subcritical state
Implementation Method 3
a supersaturation state is generated through the temperature difference based on the temperature dependence of the solubility of the starting material in the ammonia solvent
Implementation Method 4
thereby precipitating a crystal
Data Source
AI summary
A high-quality nitride crystal can be produced efficiently by charging a nitride crystal starting material that contains tertiary particles having a maximum diameter of from 1 to 120 mm and formed through aggregation of secondary particles having a maximum diameter of from 100 to 1000 μm, in the starting material charging region of a reactor, followed by crystal growth in the presence of a solvent in a supercritical state and/or a subcritical state in the reactor, wherein the nitride crystal starting material is charged in the starting material charging region in a bulk density of from 0.7 to 4.5 g/cm3 for the intended crystal growth.