Group 13 Nitride Crystal Layer M-Plane Luminance Control
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Solution Overview
Problem
Existing gallium nitride crystal layers used in light-emitting devices face issues with dislocation density and luminance efficiency, particularly as device size increases, due to anisotropic grain orientations and void formation during crystal growth.
Innovation Solution
A layer of group 13 nitride crystal with a microstructure featuring linear high-luminance light-emitting parts along the m-plane, doped with specific atoms like oxygen, silicon, and manganese, which reduces dislocation density and property deviation, and is integrated into a free-standing substrate for improved device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the device size is increased, then the luminance efficiency is improved, but voids are left on the peripheral part of the crystal
Solution Approach 1:
The patent changes the crystal growth parameters by controlling the melt composition (increasing Ga ratio) and adjusting temperature gradients to enable uniform growth across larger substrate areas while preventing void formation at peripheral regions
Solution Approach 2:
The patent performs preliminary control of melt flow patterns before crystal growth begins, ensuring uniform distribution of molten material across the substrate surface to prevent void formation during subsequent growth of larger crystals
2Reliability
If the grain size is increased, then the dislocation density is reduced, but anisotropic property affects luminance efficiency
Solution Approach 1:
The patent creates local variations in crystal orientation by controlling grain boundary formation, where specific regions have optimized orientations for light emission while maintaining overall large grain size to reduce dislocation density
Solution Approach 2:
The patent creates a composite microstructure with multiple crystal orientations coexisting in a controlled manner, where different grain regions have complementary properties that collectively improve both dislocation reduction and luminance efficiency
3Reliability
If the melt flow is controlled to increase grain size, then the dislocation density is reduced, but voids are included between the grains
Solution Approach 1:
The patent introduces controlled impurity elements as intermediaries that modify melt viscosity and surface tension, enabling uniform melt flow that fills grain boundaries and prevents void formation while allowing large grain growth to reduce dislocation density
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
The microstructured nitride layer achieves reduced dislocation density and uniform luminance across larger surfaces, enhancing the efficiency and yield of light-emitting devices by localizing high-luminance regions and suppressing property deviations.
Implementation Method 1
the upper surface being observed by cathode luminescence
Data Source
AI summary
A layer of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof has an upper surface and a bottom surface. The upper surface of a crystal layer of the group 13 nitride includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, observed by cathode luminescence. The high-luminance light-emitting part includes a portion extending along an m-plane of the crystal of the group 13 nitride. The crystal of the nitride of the group 13 element contains oxygen atoms in a content of 1×1018 atom/cm3 or less, silicon atoms, manganese atoms, carbon atoms, magnesium atoms and calcium atoms in contents of 1×1017 atom/cm3 or less, chromium atoms in a content of 1×1016 atom/cm3 or less and chlorine atoms in a content of 1×1015 atom/cm3 or less.