Resonant Cavity Micro-LED Structure for Color Purity and Low Cross-Talk
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Solution Overview
Problem
Current microLED technologies face challenges in enhancing light emission efficiency, electrical conductivity, optical cross-talk between pixels, and color purity, particularly in large-scale wafer fabrication and display applications.
Innovation Solution
The use of a distributed Bragg reflector (DBR) with electrochemical etching and dry-etched apertures for porosification, n-type electrical contacts, optical resonant cavities, and light-blocking gaps between pixels to improve light emission, conductivity, and reduce cross-talk, while also acting as a filter to purify color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional microLED fabrication is used, then manufacturing process is simple, but light emission efficiency is insufficient
Solution Approach 1:
The patent applies preliminary action by forming apertures through the DBR layers before electrochemical etching. This pre-positioning of apertures allows the etching process to efficiently access and porosify the DBR layers, enhancing light extraction without requiring complex post-processing steps. The apertures are strategically placed to optimize light emission while maintaining manufacturing feasibility.
Solution Approach 2:
The patent utilizes porous materials by electrochemically etching the DBR layers to create a porous structure. This porosification increases the surface area and light extraction efficiency of the DBR, directly improving light emission efficiency. The porous structure allows better interaction between light and the DBR layers, enhancing overall LED performance.
2Use of energy by moving object
If DBR layers are porosified to enhance light emission, then light extraction improves, but electrical conductivity deteriorates
Solution Approach 1:
The patent applies local quality by forming apertures at specific locations through the DBR layers rather than porosifying the entire structure. This localized approach allows light extraction enhancement at the aperture regions while preserving the electrical conductivity of the bulk DBR layers. The apertures are strategically positioned to minimize impact on overall device performance.
Solution Approach 2:
The patent segments the DBR layers into regions with apertures and regions without, creating a heterogeneous structure. The segmented approach allows different functional zones: aperture regions for light extraction and non-aperture regions for maintaining electrical conductivity and structural integrity.
3Manufacturing precision
If pixels are placed close together for high resolution, then display density improves, but optical cross-talk between pixels increases
Solution Approach 1:
The patent extracts harmful optical cross-talk by introducing light-blocking gaps between adjacent pixels. These gaps physically separate the optical fields of neighboring pixels, preventing light from one pixel from interfering with adjacent pixels. The gaps are strategically positioned to block cross-talk while minimizing impact on display area and resolution.
4Manufacturing precision
If light-blocking gaps are added between pixels to reduce cross-talk, then color purity improves, but manufacturing complexity increases
Solution Approach 1:
The patent merges the formation of light-blocking gaps with the existing aperture formation process. By integrating gap creation into the same fabrication sequence used for forming functional apertures, the patent achieves color purity improvement without adding significant manufacturing complexity. The combined process utilizes similar etching and deposition steps for both purposes.
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 approach enhances light emission efficiency, improves electrical conductivity, minimizes optical cross-talk, and achieves high color purity across large-scale wafer fabrication, enabling more effective and uniform microLED displays.
Implementation Method 1
a distributed Bragg reflector (DBR) with electrochemical etching and dry-etched apertures
Implementation Method 2
electrochemical etching and dry-etched apertures for porosification
Implementation Method 3
optical resonant cavities
Implementation Method 4
light-blocking gaps between pixels to improve light emission, conductivity, and reduce cross-talk
Data Source
AI summary
A method of fabricating a semiconductor device includes forming, above a substrate surface, a plurality of distributed Bragg reflector (DBR) layers to form a DBR; forming, above the DBR, a first light emitting diode (LED) configured to emit light; and forming, above the first LED, a first reflector having a higher reflectance than the DBR, such that the first reflector and the DBR define a first resonant cavity having a length effective to collimate a first wavelength of the light emitted by the first LED and propagate the collimated light of the first wavelength through the DBR.