Patterned Sapphire LED Structure for Selective Epitaxial Growth
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Solution Overview
Problem
Current light-emitting devices face challenges in achieving high light-emitting efficiency due to impurity contamination and process defects, particularly when using heterogeneous materials for substrate growth, which affect the purity and performance of the devices.
Innovation Solution
A patterned sapphire substrate with a single-crystalline alumina seed pattern and a polycrystalline alumina layer is used, allowing for selective area growth during metal organic chemical vapor deposition, which enhances the growth rate of light-emitting devices and prevents impurity contamination, thereby improving light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a heterogeneous substrate material is used for light emitting device growth, then the growth rate and productivity are improved, but impurity contamination and manufacturing precision deteriorate
Solution Approach 1:
The substrate surface is segmented into distinct single-crystalline regions and polycrystalline regions, allowing selective area growth to occur only on the single-crystalline seed patterns. This segmentation enables the system to achieve both high growth rates and high purity by confining the epitaxial growth to specific contaminated-free zones while maintaining overall substrate functionality.
Solution Approach 2:
Different regions of the substrate are given different crystal structures - single-crystalline alumina in specific patterned areas and polycrystalline alumina in other areas. The single-crystalline regions provide the necessary purity and controlled growth characteristics, while the polycrystalline regions can be removed or serve as sacrificial layers, allowing the system to achieve high purity devices through localized quality control rather than requiring the entire substrate to be perfect.
2Manufacturing precision
If selective area growth is implemented using patterned substrate, then manufacturing precision and purity are improved, but device complexity increases
Solution Approach 1:
The substrate is pre-patterned with single-crystalline alumina seed patterns before the light emitting device growth process begins. This preliminary action creates the necessary template for selective area growth, allowing the subsequent epitaxial growth to automatically occur only in the desired locations with high precision. The complexity is front-loaded into substrate preparation rather than being introduced during the device fabrication process itself.
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 enables high-purity light-emitting devices with improved light extraction efficiency and reliability by selectively growing the epitaxial layer on the single-crystalline seed pattern while minimizing growth on the polycrystalline regions, reducing process defects and contamination issues.
Implementation Method 1
performing a metal organic chemical vapor deposition process on the patterned substrate to form a light emitting device and an epitaxial layer
Implementation Method 2
A growth rate of the light emitting device on the seed pattern may be higher than a growth rate of the epitaxial layer on the polycrystalline layer, during the metal organic chemical vapor deposition process
Data Source
AI summary
Disclosed are a display device and a manufacturing method thereof. The display device includes a plurality of pixels, a light emitting device provided in each of the plurality of pixels, the light emitting device having a first surface and a second surface, which are opposite to each other, a first electrode electrically connected to the first surface of the light emitting device, a second electrode electrically connected to the second surface of the light emitting device, and a metal oxide pattern interposed between the second surface of the light emitting device and the second electrode. The metal oxide pattern is provided to cover a portion of the second surface and to expose a remaining portion of the second surface. The second electrode is electrically connected to the exposed remaining portion of the second surface, and the metal oxide pattern includes single-crystalline or polycrystalline alumina.