Oxide Adhesion Layer for LED Light Extraction and Diffusion Control
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Solution Overview
Problem
Existing light emitting diodes (LEDs) face challenges in achieving high light extracting efficiency and preventing materials from the reflecting layer from diffusing into the light emitting structure layer, which affects their performance and reliability.
Innovation Solution
A light emitting device structure is developed with a reflecting layer, an oxide-based adhesion layer, an ohmic contact layer, and a conductive protective layer, where the conductive protective layer is partially overlapped with the light emitting structure layer to enhance light extraction and prevent material diffusion, along with a manufacturing method that includes forming these layers in a specific order to improve efficiency and prevent diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflecting layer is added to improve light extracting efficiency, then light extraction is enhanced, but materials from the reflecting layer may diffuse into the light emitting structure layer
Solution Approach 1:
An adhesion layer is introduced between the reflecting layer and the light emitting structure layer. This intermediary layer prevents direct contact between the reflecting layer materials and the light emitting structure layer, thereby blocking material diffusion while maintaining the light reflecting function of the reflecting layer.
Solution Approach 2:
The adhesion layer is composed of oxide-based materials that provide both adhesive properties to bond the reflecting layer and barrier properties to prevent material diffusion. This composite structure combines multiple functions in a single layer.
2Productivity
If chip separation is performed to manufacture individual LEDs, then production is enabled, but electrical shorts may occur during separation
Solution Approach 1:
The conductive protective layer is divided into a first portion and a second portion with different conductivity characteristics. The first portion maintains electrical connection during separation, while the second portion prevents electrical shorts between adjacent chips after separation.
Solution Approach 2:
Different regions of the conductive protective layer are assigned different electrical properties. The first portion has higher conductivity for electrical connection, while the second portion has lower conductivity to prevent shorts, creating local quality variations that satisfy different functional requirements.
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 significantly enhances light extracting efficiency and prevents material diffusion, leading to improved performance and reliability of the light emitting device, while also lowering operating voltage and reducing the risk of electrical shorts during chip separation.
Implementation Method 1
an adhesion layer including an oxide-based material on the reflecting layer
Implementation Method 2
a conductive protective layer formed at the peripheral region between the light emitting structure layer and the adhesion layer
Implementation Method 3
A light emitting diode (LED) is a sort of a semiconductor device that converts electric energy into light
Data Source
Figure 1~2
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AI summary
A light emitting device according to the embodiment includes a reflecting layer; an adhesion layer including an oxide-based materialon the reflecting layer; an ohmic contact layer on the adhesion layer; and a light emitting structure layer on the ohmic contact layer.