Light Emitting Device With Corrugated Transmissive Conductive Layer
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Solution Overview
Problem
Conventional light emitting devices suffer from low light extraction efficiency and narrow orientation angles due to inferior current spreading effects and light absorption by the transmissive conductive layer, particularly in p-GaN layers.
Innovation Solution
A light emitting device with a transmissive conductive layer featuring concave and convex portions at its surface, with a higher density and larger sizes in the edge region, which refracts light at a higher angle, enhancing light extraction efficiency and widening the orientation angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a transmissive conductive layer is disposed on the second conductivity type semiconductor layer to improve current spreading, then current spreading effect is improved, but light extraction efficiency deteriorates due to light absorption by the conductive layer
Solution Approach 1:
The patent applies curvature by forming concave and convex portions on the surface of the transmissive conductive layer. These curved surface features modify the optical path of emitted light, reducing direct absorption by the conductive layer while maintaining its electrical function. The convex portions act as micro-lenses that redirect light away from the conductive layer, thereby improving light extraction efficiency without compromising current spreading.
Solution Approach 2:
The patent introduces surface topography (concave and convex portions) to the transmissive conductive layer, adding a dimensional aspect to an otherwise flat structure. This three-dimensional surface modulation creates multiple light extraction paths and angles, reducing the harmful absorption effect while preserving the two-dimensional current spreading function of the conductive layer.
2Ease of manufacture
If a conventional flat transmissive conductive layer is used, then manufacturing is simple, but orientation angle is narrow
Solution Approach 1:
The patent forms convex portions on the transmissive conductive layer that act as micro-lenses, naturally diverging light in multiple directions. This curved surface structure inherently widens the orientation angle without requiring complex external optical components, while the overall layer structure remains compatible with standard manufacturing processes.
Solution Approach 2:
The concave and convex portions create an asymmetric surface profile on the transmissive conductive layer. This asymmetry in surface topology provides multiple light extraction angles and paths, expanding the viewing and emission orientation angles compared to a symmetric flat surface, while still using the same base material and deposition techniques.
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 uneven surface structure of the transmissive conductive layer increases light refraction angles, particularly in the edge region, leading to improved light output power and a wider orientation angle compared to conventional designs.
Implementation Method 1
the concave and convex portions have a greater density in an edge region of the transmissive conductive layer than in a central region of the transmissive conductive layer... the uneven surface structure of the transmissive conductive layer increases light refraction angles
Data Source
AI summary
An embodiment provides a light-emitting element comprising: a substrate; a light-emitting structure, which is arranged on the substrate, and which comprises a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer; a light-transmissive conductive layer arranged on the second conductive semiconductor layer; and first and second electrodes electrically connected to the first and second conductive semiconductor layers, respectively, wherein the light-transmissive conductive layer has corrugated portions formed on a first surface thereof, which is directed to the second conductive semiconductor layer, and the density of the corrugated portions in the peripheral area of the light-transmissive conductive layer is larger than the density of the corrugated portions in the central area of the light-transmissive conductive layer.