Light Emitting Device Concave Portions Light Extraction
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Solution Overview
Problem
Conventional light emitting devices face challenges in enhancing light extraction efficiency and reliability due to total reflection at interfaces and concentrated electric current flow to defect areas.
Innovation Solution
The design incorporates a semiconductor laminate structure with concave portions extending up to the n-type semiconductor layer and convex portions on the substrate, along with insulating films, to reduce total reflection and prevent concentrated electric current flow to potential defect areas, thereby improving light extraction efficiency and device reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat semiconductor laminate structure is used, then the device structure is simple, but light extraction efficiency is low due to total reflection at interfaces
Solution Approach 1:
The patent introduces concave portions with curved surfaces into the semiconductor laminate structure. These curved surfaces reduce total internal reflection at the interfaces between layers with different refractive indices, thereby improving light extraction efficiency while maintaining a relatively simple manufacturing process
Solution Approach 2:
The patent adds vertical dimensionality to the structure by forming concave portions that extend from the p-type semiconductor layer down to the n-type semiconductor layer. This three-dimensional modification creates additional light extraction pathways without significantly complicating the overall device structure
2Reliability
If the semiconductor laminate structure is modified with concave portions, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The patent segments the semiconductor laminate structure by introducing multiple discrete concave portions rather than modifying the entire structure uniformly. This segmentation approach improves light extraction at critical interfaces while maintaining the simplicity of the overall device architecture
Solution Approach 2:
The concave portions are strategically positioned at specific locations where total reflection occurs most prominently. This local modification approach targets the most critical areas for light extraction improvement without unnecessarily complicating the entire device structure
3Ease of operation
If electric current flows through the semiconductor laminate, then the device functions, but current concentrates at defect areas reducing reliability
Solution Approach 1:
The concave portions create curved current pathways that distribute electric current more evenly across the semiconductor laminate structure. This curvature prevents current concentration at defect locations, reducing the risk of device failure while maintaining effective current conduction
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 enhances light extraction efficiency by reflecting light from the semiconductor laminate structure and reduces the risk of electric current concentration at defects, leading to improved reliability and performance of the light emitting device.
Implementation Method 1
light propagated in the semiconductor laminate structure portion is reflected at a side surface of an inner wall surface of a concave portion and is extracted to the transparent electrode layer side
Data Source
AI summary
The light emitting device 1 includes a substrate 2, and an n-type conductive type semiconductor layer 3, a light emitting layer 4 and a p-type conductive type semiconductor layer 5 laminated in series on a surface 2A of the substrate 2. The light emitting layer 4, the p-type conductive type semiconductor layer 5, and a portion of the n-type conductive type semiconductor layer 3 excluding the vicinity of the peripheral portion compose a semiconductor laminate structure portion 6. A p-side transparent electrode layer 14 is formed on a surface of the p-type conductive type semiconductor layer 5. The p-side transparent electrode 14 covers a substantially whole area of a predetermined current injection region 13 on a surface of the p-type conductive type semiconductor layer 5. A p-side electrode 15 is formed on a surface of the p-side transparent electrode layer 14. A plurality of concave portions 16, which penetrate the p-side transparent electrode layer 14 and enter the semiconductor laminate structure portion 6, are formed on a surface of the p-side transparent electrode layer 14.