Light Extracting Structure Layer for LED Efficiency
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Solution Overview
Problem
Light emitting diodes (LEDs) face inefficiencies in light extraction due to the refractive index mismatch between the semiconductor layer and air, leading to internal reflection and reduced light emission, which can also degrade electrical characteristics when conventional light extracting structures are employed.
Innovation Solution
A light emitting device structure featuring a first conductive semiconductor layer, an active layer, a second conductive semiconductor layer, a passivation layer, a connection layer, a light extracting structure layer with a concave-convex design, and electrode layers, which improves electrical characteristics and light extraction efficiency while minimizing degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a concave-convex light extracting structure is formed on the semiconductor layer, then light extraction efficiency is improved, but electrical characteristics are degraded
Solution Approach 1:
The device is divided into separate functional regions: a light extraction region with concave-convex structure for improving light extraction efficiency, and a separate electrode connection region on a flat surface for maintaining electrical characteristics. This segmentation allows each region to optimize its function without compromising the other.
Solution Approach 2:
The concave-convex light extracting structure is formed only in specific local regions (first and second light extracting structures) rather than across the entire semiconductor layer. The electrode is connected at a different location through a via hole, creating local quality differences that simultaneously achieve light extraction enhancement and electrical characteristic preservation.
2Ease of manufacture
If the semiconductor layer has a lower refractive index than air, then material growth is easier, but light is totally reflected and cannot be effectively emitted
Solution Approach 1:
Concave-convex structures with curved surfaces are formed on the semiconductor layer to replace the flat surface. These curved structures change the angle of light incidence at the semiconductor-air interface, reducing total internal reflection and improving light extraction efficiency while maintaining the original semiconductor material properties.
Solution Approach 2:
The light extraction problem is solved by introducing surface topology changes in the vertical dimension (concave-convex structures) rather than changing the material's refractive index. This dimensional approach allows light to escape through multiple angles created by the surface geometry.
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
Enhances light extraction efficiency and maintains or improves electrical characteristics by effectively redirecting light outward and ensuring robust electrical connections through the novel structure and manufacturing method.
Implementation Method 1
since a material constituting the light emitting semiconductor layer has a refractive index lower than that of external air, light generated from the active layer is not effectively emitted to the outside, but totally reflected from a boundary surface
Implementation Method 2
light generated from the active layer is not effectively emitted to the outside, but totally reflected from a boundary surface
Data Source
AI summary
A light emitting device according to the embodiment includes a first conductive semiconductor layer; an active layer on the first conductive semiconductor layer; a second conductive semiconductor layer on the active layer; a first passivation layer surrounding the first conductive semiconductor layer, the active layer, and the second conductive semiconductor layer; a second connection layer electrically connected to the second conductive semiconductor layer through the first passivation layer; a first light extracting structure layer on the first passivation layer and the second connection layer; a first electrode layer electrically connected to the first conductive semiconductor layer; and a second electrode layer on the first light extracting structure layer.