GaN Seed Crystal Geometry for Stable Initial Nuclei Growth
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Solution Overview
Problem
Existing methods for manufacturing gallium nitride (GaN) using the Na flux method result in unstable initial nuclei formation, leading to non-uniform GaN growth and high dislocation density.
Innovation Solution
The method involves using a seed substrate with seed crystals having a (10-11) plane on their outer peripheral surface, and optionally a recess at the center, to stabilize initial nuclei formation and prevent dislocation propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If seed crystals are formed in the shape of a circle or hexagon in a plan view, then the seed substrate can be manufactured with simple geometry, but the initial nucleus cannot be shaped stably without variation leading to non-uniform GaN growth
Solution Approach 1:
The patent changes the geometric parameters of the seed crystal by introducing a recess at the center and specifying the (10-11) plane orientation on the outer peripheral surface. This transforms the simple circular/hexagonal geometry into a more complex shape with specific crystallographic features that stabilize initial nuclei formation and achieve uniform GaN growth.
2Device complexity
If seed crystals have simple circular or hexagonal shape, then the manufacturing process is simpler, but dislocation density increases and crystal quality deteriorates
Solution Approach 1:
The patent applies local quality by creating a recess at the center of the seed crystal and specifying the (10-11) plane orientation on the outer peripheral surface. This localized structural modification with specific crystallographic orientation stabilizes the initial nuclei and prevents dislocation propagation, thereby improving overall crystal quality without requiring complete structural complexity throughout the entire seed crystal.
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 enables uniform and high-quality GaN growth by curtailing variations in initial nuclei shape and dislocation propagation, resulting in fewer defects and improved crystal quality.
Implementation Method 1
nitrogen is dissolved in a mixed melt of gallium (Ga) and sodium (Na) to thereby grow GaN in a liquid phase
Implementation Method 2
growing the group III nitride semiconductor on a seed substrate by supplying a gas containing nitrogen into a mixed melt
Data Source
AI summary
A method for manufacturing a group III nitride semiconductor, the method including a crystal growing step of growing the group III nitride semiconductor on a seed substrate by supplying a gas containing nitrogen into a mixed melt in which a group III metal and a flux are mixed. The seed substrate includes a substrate and a plurality of seed crystals provided on the substrate and including the group III nitride semiconductor, and the seed crystals each include a (10-11) plane on an outer peripheral surface thereof.