Multi-Layer LED Reflectors for Higher Light Extraction
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Solution Overview
Problem
Conventional LED technology faces challenges in maximizing light emission efficiency due to limitations in light extraction and internal absorption, particularly during the fabrication process, which leads to edge damage artifacts and reduced reflectivity.
Innovation Solution
A multiple layer reflective structure is employed, comprising a first metal reflective layer formed by sputtering and a second metal reflective layer formed by a different deposition process, such as electron beam deposition, with a capping and nucleation layer in between, to enhance reflectivity and reduce edge damage artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single metal reflective layer is formed by conventional sputtering, then the fabrication process is simple, but edge damage artifacts occur and reflectivity is reduced
Solution Approach 1:
The single metal reflective layer is segmented into multiple layers with different morphologies. The patent applies a first metal reflective layer formed by sputtering and a second metal reflective layer formed by a different deposition process, creating distinct segments that perform different functions to reduce edge damage artifacts while maintaining fabrication simplicity
Solution Approach 2:
The patent creates a composite reflective structure by combining metal layers with different morphologies and grain structures. This composite approach integrates layers formed by different deposition processes (sputtering and alternative methods) to achieve superior reflectivity and reduced edge damage compared to conventional single-layer structures
2Ease of manufacture
If a single metal reflective layer is formed by conventional sputtering, then the process is straightforward, but internal absorption of photons increases
Solution Approach 1:
The patent employs a composite reflective structure with multiple metal layers having different morphologies to reduce internal photon absorption. The combination of layers formed by different deposition processes creates a structure that minimizes energy loss while maintaining ease of manufacture through standardized fabrication procedures
3Reliability
If multiple layer reflective structures with different morphologies are employed, then light extraction is improved and reflectivity increases, but device complexity increases
Solution Approach 1:
The reflective structure is segmented into multiple layers with distinct morphologies, where each layer contributes differently to light extraction. This segmentation improves reliability by reducing internal absorption and enhancing reflectivity, while the modular nature of the segmented structure allows for systematic fabrication that manages complexity
Solution Approach 2:
The patent changes physical parameters of the metal layers, specifically their morphology and grain structure, by employing different deposition processes. This parameter variation enhances light extraction efficiency and reflectivity while maintaining controllable fabrication processes that manage device complexity
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 hybrid reflective structure improves light extraction and reduces manufacturing defects, enhancing the overall reflectivity and efficiency of LED chips.
Implementation Method 1
a first metal reflective layer formed by sputtering
Implementation Method 2
a second metal reflective layer of the same material and formed by a deposition process different from sputtering
Data Source
AI summary
Solid-state lighting devices including light-emitting diodes (LEDs) and more particularly multiple layer reflective structures for LED chips and related methods are disclosed. Multiple layer reflective structures include different metal reflective layers formed of the same metal but with different morphologies and/or grain structures. Exemplary structures include a first metal reflective layer formed by sputtering, and a second metal reflective layer of the same material and formed by a deposition process different from sputtering. Reflective structures may further include capping layers and/or nucleation layers between the first and second metal reflective layers of the same material.