Distributed Bragg Reflector for Directional LED Radiation
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Solution Overview
Problem
Conventional light-emitting diode (LED) chips have inefficiencies in radiation patterns and volume expansion during packaging, making them unsuitable for downsized electronic devices, as they primarily enhance normal incidence reflection and lack effective lateral light concentration.
Innovation Solution
A light-emitting device with a Distributed Bragg reflector comprising alternate semiconductor layers of varying aluminum concentrations and refractive indices, where the low-refractive-index parts are gradually changed towards the light-emitting semiconductor stack, enhancing directional radiation patterns and reducing volume by concentrating light towards the front.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If housing packages or lenses are used to adjust radiation patterns, then directional radiation pattern is improved, but volume of the light-emitting device increases
Solution Approach 1:
The patent merges the light-emitting function and the radiation pattern control function into a single integrated structure. The Distributed Bragg Reflector is directly integrated with the light-emitting diode chip, eliminating the need for separate housing packages or lenses. This integration achieves directional radiation pattern control while maintaining a compact volume.
Solution Approach 2:
The Distributed Bragg Reflector structure serves multiple functions simultaneously: it acts as both the light-emitting element and the radiation pattern control element. By designing the reflector with specific refractive index variations and layer structures, it achieves both light generation and directional radiation control in a single component.
2Loss of energy
If conventional Distributed Bragg Reflector structure is used, then normal incidence reflection is enhanced, but lateral light concentration is insufficient
Solution Approach 1:
The patent applies local quality by creating regions with different refractive indices within the Distributed Bragg Reflector structure. The first semiconductor layers have different refractive indices from the second semiconductor layers, creating localized optical properties that enable both normal incidence reflection and lateral light concentration. This spatial variation in optical properties allows different regions to perform different functions.
Solution Approach 2:
The patent changes the refractive index parameter throughout the Distributed Bragg Reflector structure by alternating between semiconductor layers with different compositions and refractive indices. This parameter variation enables the structure to control light propagation in multiple directions, achieving both reflection efficiency and lateral concentration simultaneously.
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 improves light-emitting device efficiency by concentrating light and achieving a directional radiation pattern without the need for bulky packaging, making it suitable for downsized applications.
Implementation Method 1
a Distributed Bragg reflector comprising alternate first semiconductor layers and second semiconductor layers
Implementation Method 2
an emission light 1033 impinging on the Distributed Bragg Reflector structure 102 at an oblique angle of incidence escapes downwardly from the side of the conventional light-emitting diode chip 100 through refraction
Implementation Method 3
After injecting a current through the first electrode 105 and through the conventional light-emitting diode chip 100, the active layer 103 emits light
Data Source
AI summary
A light-emitting device includes: a Distributed Bragg reflector comprising alternate first semiconductor layers and second semiconductor layers, wherein each first semiconductor layer comprises a low-refractive-index part having a depth; and a light-emitting semiconductor stack associated with the Distributed Bragg reflector; wherein the depths of the low-refractive-index parts of the first semiconductor layers are gradually changed in a direction toward the light-emitting semiconductor stack.