Light Emitting Device With Reflective Projections
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) have limited light emitting efficiency, restricting their use to small electronic devices due to their low light output.
Innovation Solution
A light emitting device design featuring a substrate, conductive semiconductor layers, an active layer, and a reflective layer with projections to enhance light extraction efficiency, including a metal reflective layer and light extraction patterns on the semiconductor layers to redirect and emit light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional LED structure is used, then the device is simple to manufacture, but the light emitting efficiency is low
Solution Approach 1:
The patent introduces a reflective layer with three-dimensional projections extending into the semiconductor layer, adding a vertical dimension to light management. This dimensional change allows light to be reflected and redirected multiple times within the device structure, increasing the probability of light extraction without complicating the planar manufacturing process
Solution Approach 2:
The reflective layer acts as an intermediary element between the active layer and the external environment. It mediates light propagation by reflecting photons that would otherwise be trapped, converting harmful total internal reflection into useful light extraction paths, thereby improving efficiency without requiring fundamental changes to the LED fabrication process
2Productivity
If a reflective layer with projections is added, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The reflective layer is segmented into multiple discrete projections rather than a continuous layer. This segmentation allows the projections to be formed using standard photolithography and etching processes, breaking down a complex three-dimensional structure into manufacturable discrete elements that can be created with existing semiconductor fabrication tools
Solution Approach 2:
The patent optimizes specific parameters of the projections such as height, width, spacing, and depth to achieve maximum light extraction efficiency. By carefully controlling these geometric parameters within manufacturable ranges, the design achieves high performance without requiring exotic manufacturing capabilities, balancing complexity and effectiveness
3Illumination intensity
If the upper surface of the reflective layer is wider than the lower surface, then light is reflected in directions away from the reflective layer, but manufacturing precision requirements increase
Solution Approach 1:
The projections are designed with curved or tapered profiles rather than sharp angular transitions. This curvature smooths the light reflection paths and reduces sensitivity to small variations in projection geometry, allowing broader tolerances in manufacturing while maintaining effective light redirection away from the reflective layer
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 design significantly improves light extraction efficiency, allowing for increased light emission and broader application of LEDs beyond small devices.
Implementation Method 1
a reflective layer under the substrate and including a plurality of first projections configured to reflect light emitted by the active layer in directions away from the reflective layer
Data Source
AI summary
A light emitting device including a substrate, a first conductive semiconductor layer on the substrate, an active layer on the first conductive semiconductor layer, a second conductive semiconductor layer on the active layer, and a reflective layer under the substrate and including a light reflection pattern configured to reflect light emitted by the active layer in directions away from the reflective layer.