Patterned Substrate Dislocation Control for Micro LED Uniformity
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Solution Overview
Problem
Micro LED displays face issues with uneven dislocation distribution in epitaxial structures, leading to variations in light-emitting wavelengths and display color uniformity due to mismatched lattice constants between epitaxial materials and substrates during manufacturing.
Innovation Solution
A light-emitting device structure with a patterned substrate featuring alternating first and second dislocation density regions, where the first regions have lower dislocation density and are correspondingly disposed with specific patterned structures, ensuring a regular and even dislocation distribution to improve light output and color uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional epitaxial growth on flat substrate is used, then manufacturing process is simple, but dislocation distribution is random and uneven causing color non-uniformity
Solution Approach 1:
The substrate surface is segmented into multiple regions with different dislocation density characteristics. By dividing the epitaxial structure into regions with controlled dislocation densities (first regions with lower density and second regions with higher density), the patent achieves uniform overall dislocation distribution. This segmentation allows precise control over light-emitting properties across different areas of the device.
Solution Approach 2:
Different regions of the epitaxial structure are given different local qualities in terms of dislocation density. The first dislocation density regions and second dislocation density regions have deliberately different dislocation characteristics, allowing each region to contribute differently to the overall light emission. This local quality differentiation enables uniform color output across the entire device surface.
2Reliability
If lattice constant mismatch between epitaxial material and substrate is addressed by conventional methods, then crystal growth is achieved, but threading dislocations are formed with random distribution
Solution Approach 1:
The substrate is pre-patterned with specific structures before epitaxial growth begins. These pre-formed patterns on the substrate surface guide the subsequent epitaxial growth process, ensuring that dislocations are generated and distributed in a controlled manner from the outset. This preliminary action prevents random dislocation formation during crystal growth.
Solution Approach 2:
The patent controls and changes the dislocation density parameter across different regions of the epitaxial structure. By deliberately creating regions with different dislocation densities and strategically distributing them, the patent transforms the uncontrolled random dislocation parameter into a controlled variable that can be optimized for uniform light output and color consistency.
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 structured epitaxial layer achieves improved light output uniformity and color consistency by averaging stress and enhancing epitaxial quality, resulting in better performance and efficiency of micro LED displays.
Implementation Method 1
a lattice constant of an epitaxial material (for example, gallium nitride) does not match a lattice constant of a substrate (for example, a sapphire substrate) for crystal growth
Data Source
AI summary
A light-emitting device includes an epitaxial structure, and first and second electrodes. The epitaxial structure has a first surface and a second surface opposite to each other, first dislocation density regions and second dislocation density regions. The first dislocation density regions and the second dislocation density regions are alternately disposed between the first surface and the second surface. A dislocation density of each first dislocation density region is lower than a dislocation density of each second dislocation density region and a quantity of the first dislocation density regions is at least ten. The epitaxial structure further includes a light-emitting layer, a first-type semiconductor layer and a second-type semiconductor layer disposed on two opposite sides of the light-emitting layer. The first electrode and the second electrode are electrically connected to the first-type semiconductor layer and the second-type semiconductor layer, respectively. A light-emitting device structure adopting the light-emitting device is provided.