Patterned Sapphire LED Structure for Insulating Layer Coverage
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Solution Overview
Problem
The lattice mismatch between sapphire and GaN in optoelectronic devices results in high defect density and reduced light-extraction efficiency, which is not adequately addressed by existing patterned sapphire substrates.
Innovation Solution
A light-emitting device with a patterned substrate featuring protrusions and recesses, where the epitaxial unit is selectively etched to create a first area with reduced height difference, ensuring complete removal of the epitaxial layer and improving coverage continuity of the insulating layer, thereby enhancing structural integrity and luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a patterned sapphire substrate is applied to reduce defect density, then the light-extraction efficiency is improved, but the height difference between covered and uncovered areas increases, causing poor coverage continuity of the insulating layer
Solution Approach 1:
The patent applies different treatments to different areas of the substrate. The first area (uncovered by epitaxial layer) is etched to create protrusions with reduced height, while the second area (covered by epitaxial layer) maintains its original height. This local differentiation allows the insulating layer to cover continuously across both areas while preserving the light-extraction efficiency benefits of the patterned substrate structure.
2Manufacturing precision
If the epitaxial layer is completely removed from the first area, then the coverage continuity is improved, but the structural integrity may be compromised
Solution Approach 1:
The patent performs preliminary etching of the substrate in the first area before completing the epitaxial layer formation. By creating protrusions in advance with controlled height reduction (etching depth less than the thickness of the epitaxial layer), the structure is prepared to receive the insulating layer continuously while maintaining sufficient structural support from the remaining substrate and epitaxial layer combination.
Data Source
AI summary
A light-emitting device includes a substrate and an epitaxial unit. The substrate has a first and a second surface. The substrate is formed on the first surface with a plurality of protrusions. The epitaxial unit includes a first semiconductor layer, an active layer, and a second semiconductor layer that are sequentially disposed on the first surface of the substrate. The first surface of the substrate has a first area that is not covered by the epitaxial unit, and a second area this is covered by the epitaxial unit. A height difference (h2) between the first area and the second area is no greater than 1 μm. A display apparatus and a lighting apparatus are also disclosed.