LED Structured Substrate Cavity for Side Light Extraction
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Solution Overview
Problem
Current light-emitting devices, such as LEDs, face inefficiencies in extracting light from the sides due to the lack of effective structures that enhance lateral light emission, leading to reduced light extraction efficiency and non-uniform emission patterns.
Innovation Solution
A semiconductor light-emitting device with a hollow cavity formed in the substrate, featuring sloped sidewalls coated with a reflective material and a high refractive index coating on the surface, which enhances light extraction through the external sidewalls by increasing total internal reflection and reducing top surface light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light emitting devices use conventional flat substrates, then the device structure is simple, but light extraction efficiency from the sides is poor
Solution Approach 1:
The substrate is segmented by forming a hollow cavity within it, dividing the原本 continuous substrate into regions that guide light differently. This segmentation creates distinct optical paths that improve side light extraction while maintaining overall substrate integrity and manufacturability
Solution Approach 2:
The invention transitions from a conventional flat two-dimensional substrate surface to a three-dimensional structure with a hollow cavity. This dimensional change creates internal reflective surfaces that redirect light toward the sides, significantly improving light extraction efficiency without complicating the manufacturing process
2Loss of energy
If reflective materials are added to enhance side light extraction, then light extraction efficiency improves, but device complexity increases
Solution Approach 1:
The reflective material coating is merged with the cavity structure, where the cavity provides the geometric configuration for light redirection and the reflective coating enhances this effect. This combination achieves superior light extraction without requiring separate complex optical components or multiple discrete elements
Solution Approach 2:
The invention changes the optical parameters of the substrate by introducing a reflective coating with specific reflectivity characteristics. This parameter change enhances light extraction efficiency through the cavity structure without fundamentally altering the device architecture or requiring complex additional components
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 solution achieves improved light extraction efficiency and uniformity from the sides of the device, reducing spottiness and eliminating the need for complex secondary optics, while maintaining a compact and cost-effective design.
Implementation Method 1
The reflecting surface is inclined to surfaces of growth of semiconductor layers. Light emitted from the light-emitting layer is reflected by the reflecting surface, so that the reflected light emerges from side surfaces of the light-emitting element to the outside without passing through the semiconductor layers.
Implementation Method 2
a high refractive index coating is formed on the first surface having a refractive index of at least 1.5. Light is efficiently extracted through external sidewalls of the semiconductor light emitting device.
Data Source
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AI summary
Embodiments of the invention include a semiconductor light emitting device. The device includes a substrate having a first surface and a second surface opposite the first surface. The device further includes a semiconductor structure disposed on the first surface of the substrate. A cavity is disposed within the substrate. The cavity extends from the second surface of the substrate. The cavity has a sloped side wall.