GaN Bulk Crystal Growth via Concentration Matching
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Solution Overview
Problem
Current methods for growing gallium nitride (GaN) bulk crystals face challenges in achieving high-quality crystals beyond 1 mm in thickness due to issues like lattice bowing and cracking, which are exacerbated by mismatched electron and oxygen concentrations between seed crystals and grown layers.
Innovation Solution
The method involves matching the electron and oxygen concentrations between seed crystals and grown layers by adjusting growth conditions, such as adding oxygen during specific reaction sequences, to reduce mechanical stress and improve crystal quality, lattice curvature, and crack density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If bulk GaN crystals are grown beyond 1 mm thickness using conventional methods, then crystal thickness increases, but lattice bowing and cracking occur due to mismatched electron and oxygen concentrations
Solution Approach 1:
The patent applies parameter changes by precisely controlling electron concentration and oxygen concentration during different growth stages. By adjusting these chemical parameters to match between seed crystal and grown layer, the method prevents lattice bowing and cracking, enabling reliable growth of bulk GaN crystals beyond 1 mm thickness while maintaining high crystal quality
Solution Approach 2:
The patent employs preliminary action by pre-matching the electron and oxygen concentrations of the seed crystal before initiating bulk crystal growth. This preparatory step ensures that when growth proceeds beyond 1 mm thickness, lattice mismatches are minimized from the outset, preventing defects before they occur
2Productivity
If electron and oxygen concentrations are mismatched between seed crystal and grown layer, then growth speed increases, but mechanical stress and crack density increase
Solution Approach 1:
The patent resolves this contradiction by dynamically adjusting concentration parameters during growth. By optimizing electron and oxygen concentration levels to match between seed and grown layer, the method maintains high growth speed while simultaneously minimizing mechanical stress and crack density, eliminating the trade-off between productivity and defect reduction
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 bulk GaN crystals with improved quality, reduced lattice bowing, and lower crack density, enabling the production of high-quality wafers suitable for advanced optoelectronic and electronic devices.
Implementation Method 1
Grown in a sealed vessel at a temperature of about 500° C. and a pressure of about 2000 psi for about 10 days
Implementation Method 2
a sealed vessel at a temperature of about 500° C. and a pressure of about 2000 psi
Data Source
AI summary
Bulk crystal of group III nitride having thickness greater than 1 mm with improved crystal quality, reduced lattice bowing and/or reduced crack density and methods of making. Bulk crystal has a seed crystal, a first crystalline portion grown on the first side of the seed crystal and a second crystalline portion grown on the second side of the seed crystal. Either or both crystalline portions have an electron concentration and/or an oxygen concentration similar to the seed crystal.The bulk crystal can have an additional seed crystal, with common faces (e.g. same polarity, same crystal plane) of seed crystals joined so that a first crystalline part grows on the first face of the first seed crystal and a second crystalline part grows on the first face of the second seed crystal. Each crystalline part's electron concentration and/or oxygen concentration may be similar to its corresponding seed crystal.