Segmented UV Light Extraction Coating for Semiconductor Devices
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Solution Overview
Problem
Semiconductor light emitting devices for ultraviolet light face challenges in light extraction efficiency due to high internal reflection caused by refractive index differences, and existing resin coatings are prone to cracking and exfoliation under thermal stress.
Innovation Solution
A semiconductor light emitting device with a coating part made of isolated, low-refractive-index material applied to the extraction surface, reducing refractive index differences and residual stress, thereby enhancing light extraction efficiency and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the light emitting surface is sealed with a resin coating to reduce internal reflection, then light extraction efficiency is improved, but the coating may crack or exfoliate due to temperature cycles and residual stress
Solution Approach 1:
The coating part is divided into multiple isolated regions rather than forming a continuous layer. This segmentation reduces residual stress accumulation and prevents crack propagation across the entire surface, thereby improving coating durability while maintaining light extraction efficiency through the distributed coating structure
Solution Approach 2:
The coating is applied selectively to specific regions of the light emitting surface rather than uniformly across the entire surface. This local application reduces the overall stress burden on the coating structure while still providing refractive index matching benefits in the coated regions, balancing durability and optical performance
2Loss of energy
If a continuous resin coating is applied to the light emitting surface, then internal reflection is reduced, but residual stress causes cracking and exfoliation
Solution Approach 1:
The continuous coating is segmented into isolated regions, which interrupts stress continuity and prevents crack propagation. The segmented structure maintains optical benefits in coated areas while significantly improving mechanical integrity and resistance to thermal cycling
Solution Approach 2:
The coating structure is pre-designed with isolated regions before stress accumulation occurs. This preliminary structural configuration prevents stress buildup that would lead to cracking, proactively addressing the durability issue before it manifests during operation
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 improves light extraction efficiency and reduces the occurrence of cracks and exfoliation, resulting in a more reliable and durable semiconductor light emitting device for ultraviolet light emission.
Implementation Method 1
the refractive index of ordinary nitride-based semiconductor layers is significantly greater than that of air and because ultraviolet light is absorbed significantly by some of the nitride-based materials
Data Source
AI summary
A semiconductor light emitting device includes: a light emitting part for emitting ultraviolet light; and a coating part that coats a part of an extraction surface from which the ultraviolet light emitted by the light emitting part is extracted. The coating part is comprised of a plurality of isolated parts distanced from each other, and the isolated part is made of a second material having a refractive index that is lower than a refractive index of a first material forming the extraction surface.