LED Reflective Contact Structure with Stepped Openings
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Solution Overview
Problem
Existing LEDs face challenges in improving external quantum efficiency due to light absorption by metal electrodes, and reflective layers have limited reflective efficiency, necessitating a solution to enhance light-emitting efficiency.
Innovation Solution
The LED design includes an epitaxial structure with a transparent conductive layer, an insulating structure with a step-defined opening, and a metal reflective layer that fills the openings and forms electrical contact with the second semiconductor layer, increasing the contact area and reflection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a reflective layer is disposed between the metal electrode and the epitaxial layer, then the light-emitting efficiency of the LED is improved, but the reflective efficiency of the reflective layer is very limited
Solution Approach 1:
The patent transitions from a conventional planar reflective layer to a three-dimensional micro-cavity structure with stepped openings. The insulating structure features multiple levels of openings (first openings and second openings) that create vertical and lateral dimensions for light reflection, fundamentally changing the geometric dimensionality of the reflective interface to enhance light extraction efficiency.
Solution Approach 2:
The reflective structure is segmented into multiple functional zones: the insulating structure with stepped openings, the metal reflective layer filling these openings, and the transparent conductive layer. This segmentation allows each component to perform its specific function optimally - the insulating structure provides structural support and light guiding, the metal layer provides high reflectivity, and the transparent conductive layer enables electrical contact while maintaining optical transparency.
2Reliability
If a metal electrode is disposed above the epitaxial layer, then electrical contact is achieved, but light emitted from the epitaxial layer is easily absorbed by the metal electrode
Solution Approach 1:
The patent introduces a transparent conductive layer as an intermediary between the metal electrode and the epitaxial layer. This intermediate layer serves dual functions: it maintains electrical contact with the semiconductor layer while being optically transparent to allow light to pass through without absorption by the underlying metal electrode. The insulating structure with stepped openings further mediates the interaction between light and metal by providing reflection pathways.
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 the light-emitting efficiency of the LED by increasing the reflection efficiency of the metal reflective layer, effectively addressing the limitations of previous technologies.
Implementation Method 1
a metal reflective layer, where the metal reflective layer is disposed on a side of the insulating structure facing away from the transparent conductive layer, the first opening and the second opening are filled with the meal reflective layer
Data Source
AI summary
An LED and a light emitting device are provided, which includes an epitaxial structure, a transparent conductive layer, an insulating structure and a metal reflective layer. The epitaxial structure includes a first semiconductor layer, an active layer and a second semiconductor layer. The transparent conductive layer is disposed on the second semiconductor layer. The insulating structure is disposed on the transparent conductive layer, and an opening is defined in the insulating structure. The transparent conductive layer is exposed from the opening. A step portion is formed on a sidewall of the opening, and divides the opening into a first opening and a second opening. An opening width of the first opening is smaller than that of the second opening. The metal reflective layer is disposed on the insulating structure. The metal reflective layer fills the first opening and the second opening, and forms electrical contact with the second semiconductor layer.