III-Nitride Light Emitting Device with Textured Hexagonal Oxide Substrate
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
III-nitride light emitting devices grown on non-native substrates like sapphire or SiC suffer from strain and crystal defects due to lattice constant mismatch, leading to poor performance and light trapping issues.
Innovation Solution
A semiconductor structure with a III-nitride light emitting layer grown on a substrate with a lattice constant closely matched to the III-nitride layer, featuring texturing or reduced thickness to enhance light extraction, and using a substrate that can be etched with wet chemicals to form light extraction features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If III-nitride light emitting devices are grown on non-III-nitride substrates like sapphire or SiC, then device fabrication becomes feasible, but strain and crystal defects occur due to lattice constant mismatch
Solution Approach 1:
The patent changes the substrate material parameter from conventional sapphire or SiC to a specifically selected non-polar or semi-polar III-nitride substrate with controlled orientation. This parameter change reduces lattice mismatch and minimizes strain and crystal defects in the grown III-nitride layers, thereby improving device reliability while maintaining fabrication feasibility.
2Ease of manufacture
If III-nitride layers are grown on substrates with different lattice constants, then device fabrication is enabled, but light is trapped inside the structure by waveguide formation
Solution Approach 1:
The patent introduces curved or non-planar surface structures on the substrate or device layers. This curvature disrupts the planar waveguide formation that traps light, enabling improved light extraction while maintaining the benefits of growing on non-III-nitride substrates for fabrication feasibility.
3Ease of manufacture
If conventional substrate materials are used, then device fabrication is simplified, but light extraction efficiency is reduced due to waveguide effects
Solution Approach 1:
The patent addresses light extraction by introducing features in the vertical dimension (such as etched holes, inverted pyramids, or other three-dimensional surface structures) rather than relying solely on planar modifications. This dimensional approach disrupts waveguide modes and enhances light extraction efficiency while maintaining fabrication simplicity through established etching and growth techniques.
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 approach results in reduced strain and improved light extraction efficiency, enhancing the performance and reliability of III-nitride devices by minimizing guided optical modes and facilitating the use of wet chemical etching for substrate texturing.
Implementation Method 1
A surface of the substrate opposite the surface on which the semiconductor structure is grown is textured. The texturing may improve light extraction.
Implementation Method 2
A thickness of the semiconductor structure is selected to reduce a number of guided optical modes within the semiconductor structure, which may improve light extraction.
Data Source
AI summary
Methods and apparatus are described. An apparatus includes a hexagonal oxide substrate and a III-nitride semiconductor structure adjacent the hexagonal oxide substrate. The III-nitride semiconductor structure includes a light emitting layer between an n-type region and a p-type region. The hexagonal oxide substrate has an in-plane coefficient of thermal expansion (CTE) within 30% of a CTE of the III-nitride semiconductor structure.