Micro-LED Semiconductor Reflector for Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional Micro-LED devices face challenges in manufacturing Ohmic contact layers with reduced areas for efficient light extraction, leading to absorption issues and reduced light emission efficiency.
Innovation Solution
Incorporating a semiconductor reflector between the light emitting layer and the n-type contact layer, along with a first insulating layer with a refractive index different from the p-type semiconductor layer, to prevent light absorption and enhance light emission efficiency, and using a distributed Bragg reflector with alternating layers to redirect light and reduce total internal reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the Ohmic contact layer area is reduced to minimize light absorption, then light extraction efficiency is improved, but manufacturing difficulty increases for Micro-LEDs
Solution Approach 1:
The patent introduces a semiconductor reflector layer as an intermediary component between the light emitting layer and the n-type contact layer. This reflector prevents light generated in the light emitting layer from being absorbed by the contact layer, thereby reducing light absorption loss without requiring reduction of the contact layer area, thus maintaining ease of manufacture while improving light extraction efficiency
Solution Approach 2:
The patent extracts the light reflection function from the contact layer system by introducing a dedicated semiconductor reflector layer. This separate component specifically addresses light absorption loss without affecting the contact layer's electrical function or area requirements, resolving the manufacturing difficulty while achieving energy loss reduction
2Loss of energy
If a semiconductor reflector is added to prevent light absorption, then light emission efficiency is enhanced, but device complexity increases
Solution Approach 1:
The semiconductor reflector layer is designed with specific material composition parameters (AlGaInP with varying Al content) and thickness parameters (50-200 nm) that enable it to achieve the desired light reflection function. By optimizing these parameters, the reflector provides effective light emission efficiency enhancement while maintaining a simple single-layer structure that does not significantly increase device complexity
3Loss of energy
If the top surface of p-type semiconductor layer is made rough to reduce total internal reflection, then light extraction efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs a self-service approach by using the same spin coating process that forms the insulating layer to simultaneously create the rough surface structure. The inherent variations in spin coating naturally produce the desired surface roughness without requiring additional precision manufacturing steps, thus improving light extraction efficiency while maintaining reasonable manufacturing precision requirements
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 significantly enhances light emission and extraction efficiency by preventing light absorption and minimizing losses due to total internal reflection, resulting in improved performance for Micro-LED devices.
Implementation Method 1
a semiconductor reflector between the light emitting layer and the n-type contact layer so as to prevent the n-type contact layer from absorbing light which is generated in the light emitting layer
Implementation Method 2
a first insulating layer having a refractive index different from a refractive index of the p-type semiconductor layer
Implementation Method 3
improved light extraction efficiency can be provided for the light emitting device because of reducing loss due to total internal reflection between air and the top surface of the p-type semiconductor layer
Data Source
AI summary
A light emitting device includes a stacked structure and a first insulating layer covering at least side surfaces of the stacked structure including a p-type and n-type semiconductor layers, a light emitting layer sandwiched between the p-type and n-type semiconductor layers, an n-type electrode on the n-type semiconductor layer, an n-type contact layer sandwiched between the n-type semiconductor layer and the n-type electrode, a p-type electrode on the p-type semiconductor layer, an n-type contact pad on the n-type electrode, a p-type contact pad on the p-type electrode, and a semiconductor reflector between the light emitting layer and the n-type contact layer including multiple periods, each period including at least a first layer and at least a second layer having a refractive index different from a refractive index of the first layer. The light emitting device could be applied to wide color gamut (WCG) backlight modules or ultra-thin backlight modules.