Light Emitting Device Reliability Enhancement Layer
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Solution Overview
Problem
Existing light emitting devices using nitride semiconductors face issues with non-uniform etching depth and crystal defects, leading to reduced electrical and optical reliability, especially in high-power lighting systems, due to chemical etching methods that cause current leakage and excessive etching.
Innovation Solution
Incorporating a reliability enhancement layer with a specific energy band gap and thickness between the active layer and the electron injection layer to prevent excessive etching and current leakage, ensuring uniform etching depth and improved light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If chemical etching is used to make the n-GaN layer surface rough, then light extraction efficiency is improved, but etching depth non-uniformity occurs and current leakage increases
Solution Approach 1:
The patent introduces an electron block layer as an intermediary between the n-GaN layer and the active layer. This layer acts as a mediator that prevents harmful electron leakage from reaching the active layer while allowing the n-GaN layer surface to be etched for improved light extraction. The electron block layer thus enables the simultaneous achievement of both light extraction efficiency and electrical reliability.
Solution Approach 2:
The electron block layer is designed as a thin, sacrificial layer that can be easily formed and removed or integrated into the final structure. This disposable-like approach allows for effective current blocking without adding significant complexity or cost to the manufacturing process, enabling the n-GaN layer to be etched aggressively for light extraction while the electron block layer prevents reliability issues.
2Illumination intensity
If the n-GaN layer is etched to improve light extraction, then light extraction efficiency increases, but crystal defects are excessively etched causing current leakage
Solution Approach 1:
The patent applies preliminary anti-action by forming the electron block layer before the n-GaN layer is etched. This pre-formed layer creates a protective barrier that counteracts the harmful effect of excessive etching at crystal defect regions. When the n-GaN layer is subsequently etched to improve light extraction, the electron block layer is already in place to prevent current leakage through etched crystal defects.
3Reliability
If a reliability enhancement layer is added to prevent current leakage, then electrical reliability improves, but device complexity increases
Solution Approach 1:
The patent optimizes the electron block layer thickness to a specific range (50-500 nm) to achieve effective electron blocking while minimizing the increase in device complexity. By carefully controlling this parameter, the layer provides sufficient reliability improvement without adding excessive structural complexity or affecting other device performance parameters such as light extraction and electrical injection efficiency.
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 enhances the electrical and optical reliability of light emitting devices by preventing current leakage and ensuring uniform etching, thereby improving the yield and performance of high-power lighting systems.
Implementation Method 1
the surface of an n-GaN layer is made rough by chemical etching to improve light extraction efficiency
Implementation Method 2
a second conductive type third semiconductor layer disposed on the reliability enhancement layer and comprising a light extraction pattern
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
Provided are a light emitting device, a light emitting device package, and a lighting system. The light emitting device comprises a first conductive type first semiconductor layer, an active layer, a second conductive type second semiconductor layer, a reliability enhancement layer, and a second conductive type third semiconductor layer. The active layer is disposed on the first conductive type first semiconductor layer. The second conductive type second semiconductor layer is disposed on the active layer. The reliability enhancement layer is disposed on the second conductive type second semiconductor layer. The second conductive type third semiconductor layer is disposed on the reliability enhancement layer and comprises a light extraction pattern. The reliability enhancement layer and the active layer are spaced apart from each other by a distance of 0.3 µm to 5 µm.