Light Emitting Device Electrode Structure for Enhanced Light Extraction
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Solution Overview
Problem
Current light emitting devices face challenges in maximizing light reflection efficiency and extraction efficiency, which affect productivity and overall performance.
Innovation Solution
The design includes a light emitting structure with a first conductive type semiconductor layer, an active layer, and a second conductive type semiconductor layer, along with a second electrode layer featuring a conductive transparent layer and omnidirectional reflective layers with a lower refractive index than the semiconductor layer, surrounded by an insulating layer to enhance light reflection and extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional electrode layer structure is used, then the device structure is simple, but light reflection efficiency is insufficient
Solution Approach 1:
The second electrode layer is divided into multiple functional sub-layers: a reflective layer (first reflective layer) for light reflection, a conductive transparent layer for electrical conduction and light transmission, and an insulating layer for electrical isolation. This segmentation allows each layer to perform its specific function optimally, achieving high light reflection efficiency while maintaining manageable structural complexity.
Solution Approach 2:
The electrode layer structure combines multiple materials with different properties: reflective materials (such as metal layers) for light reflection, transparent conductive materials (such as ITO, IZO, AZO) for electrical conduction and light transmission, and insulating materials for electrical isolation. This composite structure achieves superior overall performance that cannot be obtained with a single material.
2Reliability
If the second electrode layer is disposed close to the light emitting structure, then device size is reduced, but contamination occurs during chip separation
Solution Approach 1:
An insulating layer is introduced as an intermediary between the second electrode layer and the light emitting structure. This insulating layer prevents direct contact and potential contamination during chip separation processes while maintaining the compact structure. The insulating layer acts as a protective barrier that ensures reliability without significantly increasing device height.
3Loss of energy
If omnidirectional reflective layers are added to the electrode structure, then light extraction efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The omnidirectional reflective function is merged into the existing second electrode layer structure by integrating a reflective layer with conductive transparent layers and insulating layers. This combination achieves high light extraction efficiency while using standard semiconductor fabrication processes, avoiding the need for separate complex manufacturing steps.
Solution Approach 2:
The reflective layer's optical parameters (refractive index, thickness, material composition) are optimized to achieve omnidirectional reflection across the desired wavelength range. By adjusting these parameters, high light extraction efficiency is achieved while maintaining compatibility with existing manufacturing processes.
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
This configuration improves light extraction efficiency by maximizing reflectivity and preventing contamination during chip separation, thereby enhancing productivity and reliability.
Implementation Method 1
the second electrode layer includes a plurality of first reflective layers that contact the second conductive type semiconductor layer and are spaced from one another by a predetermined distance
Implementation Method 2
An index of refraction of the omnidirectional reflective layer may be smaller than an index of refraction of the second conductive type semiconductor layer
Data Source
Figure 1~2A
Figure 2B~2D
Figure 2E~2F
AI summary
Disclosed is a light emitting device including a light emitting structure including a first conductive type semiconductor layer, an active layer and a second conductive type semiconductor layer, a first electrode layer, a second electrode layer disposed between the light emitting structure and the first electrode layer, and an insulating layer surrounding the edge of the second electrode layer under the second conductive type semiconductor layer, the insulating layer being disposed between the second electrode layer and the first electrode layer, wherein the first electrode layer passes through the second electrode layer, the second conductive type semiconductor layer and the active layer, and contacts the first conductive type semiconductor layer, and the second electrode layer comprises a plurality of first reflective layers that contact the second conductive type semiconductor layer and are spaced from one another by a predetermined distance.