Micro LED Electrode and Reflective Layer Layout for Light Extraction
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Solution Overview
Problem
Existing micro LED elements face challenges in improving light extraction efficiency.
Innovation Solution
A light-emitting device configuration that includes a substrate, a first stacked body with a p-type semiconductor layer, a light-emitting layer, and an n-type semiconductor layer, along with electrodes and insulating layers, is proposed. The configuration features a tapered portion in the stacked body and a light-transmitting n-electrode, along with a reflective upper metal layer and a light-transmissive member to enhance light reflection and transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional micro LED element structure is used, then the device is simple to manufacture, but light extraction efficiency is low
Solution Approach 1:
The device is divided into distinct functional layers including a light-emitting layer, a light-transmitting electrode with light incident surface, and a reflective electrode. This segmentation allows each layer to be optimized for its specific function, improving overall light extraction efficiency while maintaining manufacturability through standardized layer fabrication processes.
Solution Approach 2:
A light-transmitting electrode is introduced as an intermediary component between the light-emitting layer and the external environment. This electrode has a specifically designed light incident surface that facilitates light extraction, acting as a mediator that transforms the light generation process into efficient light emission without complicating the overall manufacturing process.
2Volume of moving object
If the light-emitting element size is reduced for miniaturization, then device size decreases, but light extraction efficiency deteriorates
Solution Approach 1:
The light-transmitting electrode is designed with a specific light incident surface configuration that concentrates optical extraction efforts at critical locations. This local optimization of light extraction properties at the electrode-light emitting layer interface compensates for the reduced overall device size, maintaining high light extraction efficiency in miniaturized structures.
Solution Approach 2:
The invention addresses the size-efficiency tradeoff by optimizing the vertical stacking configuration and light incident surface geometry rather than simply scaling down all dimensions. This dimensional optimization allows miniaturization while preserving light extraction performance through improved optical path management in the vertical dimension.
3Productivity
If adjacent light-emitting elements are placed closer for higher density, then device density increases, but crosstalk between elements increases
Solution Approach 1:
The harmful optical crosstalk between adjacent light-emitting elements is extracted and redirected by the reflective electrode. The reflective electrode captures stray light that would otherwise cause crosstalk and redirects it back toward the light-transmitting electrode, effectively removing the harmful effect while allowing higher element density.
4Loss of energy
If a light-transmitting electrode is added to improve light extraction, then light extraction efficiency improves, but device complexity increases
Solution Approach 1:
The light-transmitting electrode serves multiple functions simultaneously: it acts as an electrical electrode for current injection, provides a light incident surface for efficient light extraction, and works in conjunction with the reflective electrode to manage optical paths. This multi-functionality reduces the need for additional separate components, maintaining device simplicity while improving light extraction efficiency.
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 proposed configuration enhances light extraction efficiency by effectively reflecting and transmitting light, while also enabling miniaturization and reducing crosstalk between light-emitting elements.
Implementation Method 1
a second electrode provided on a side of the first stacked body opposite to the substrate, having a light-transmitting property
Implementation Method 2
a reflective upper metal layer to enhance light reflection and transmission
Data Source
AI summary
A light-emitting device including a substrate; a first stacked body including a first semiconductor layer, a second semiconductor layer, and a first light-emitting layer provided between the first semiconductor layer and the second semiconductor layer; a first electrode provided between the substrate and the first stacked body, and electrically coupled to the first semiconductor layer; a second electrode provided on a side of the first stacked body opposite to the substrate, having a light-transmitting property, including a first facing surface facing the substrate, and electrically coupled to the second semiconductor layer; a first insulating layer including a first portion provided at a side surface of the first stacked body, and a second portion provided at the first facing surface, and extending from the first portion along the first facing surface; and a first metal layer provided over the first portion and the second portion.