Textured LED Subsidewall Laser Cleaving
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Solution Overview
Problem
Conventional light emitting devices with flat substrates suffer from reduced light extraction efficiency due to total internal reflection, as the refractive index of the substrate differs from the external environment.
Innovation Solution
A light emitting device with a substrate having a substantially textured sidewall, fabricated by forming discontinuous holes or continuous lines on the substrate using a laser beam and subsequent etching, which increases light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat substrate is used in conventional light emitting devices, then the manufacturing process is simple, but the light extraction efficiency is reduced due to total internal reflection
Solution Approach 1:
The patent applies surface curvature by creating a textured substrate with non-planar features including convex and concave regions. This curvature modifies the optical path of emitted light, reducing total internal reflection at the substrate-air interface and improving light extraction efficiency while maintaining manufacturing feasibility through established texturing techniques
Solution Approach 2:
The patent implements local quality changes by creating discrete textured regions with varying depths and shapes on the substrate surface. Different areas have different texturing characteristics, allowing optimization of light extraction in specific zones while maintaining overall structural integrity and manageable manufacturing complexity
2Loss of energy
If the substrate surface is made textured to improve light extraction, then light extraction efficiency increases, but the manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the substrate surface into multiple discrete textured regions or patterns rather than creating a uniformly complex structure. This segmentation allows the light extraction function to be achieved through repeated simpler units, reducing overall manufacturing complexity while maintaining effective light extraction across the entire substrate surface
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 textured sidewall enhances light extraction efficiency by reducing total internal reflection and improving light output.
Implementation Method 1
because the surface of the transparent substrate 10 of the conventional light emitting device 100 as shown in FIG. 1 is substantially flat and the refractive index of the transparent substrate 10 is different from the refractive index of the external environment, the total internal reflection (TIR) occurs when a light A emitted from the active layer 122
Implementation Method 2
forming a plurality of discontinuous holes or continuous lines on the substrate by a laser beam
Data Source
AI summary
A method of fabricating a light emitting device comprising: providing a substrate, wherein the substrate comprises a first major surface and a second major surface opposite to the first major surface, forming a plurality of light emitting stack layers on the first major surface, forming an etching protection layer on the plurality of light emitting stack layers, forming a plurality of discontinuous holes or continuous lines on the substrate by a laser beam with the depth of 10˜150 μm, cleaving the substrate through the plurality of discontinuous holes or continuous lines, providing a adhesion layer on the second major surface of the substrate, and expanding the adhesion layer to form a plurality of separated light emitting device.