Void-Structured LED Display Pixels for Lattice-Mismatch Defect Relief
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Solution Overview
Problem
Existing display devices face challenges in minimizing defects during the growth of light emitting elements, particularly those emitting long wavelength bands, due to strain and lattice constant differences in semiconductor layers.
Innovation Solution
A display device design featuring a semiconductor pattern with a lattice constant greater than the semiconductor layer, which relieves strain and increases the lattice constant, thereby minimizing defects. This is achieved by forming a void between the semiconductor layer, semiconductor pattern, and common electrode layer, and optimizing the arrangement of light emitting elements to reduce interface areas where different lattice constants contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light emitting element of long wavelength band is grown on a semiconductor layer, then the device can emit longer wavelength light, but internal defects increase due to strain and lattice constant differences
Solution Approach 1:
A semiconductor pattern layer with a lattice constant greater than both the semiconductor layer and the substrate is introduced as an intermediary between the semiconductor layer and the substrate. This intermediate layer acts as a buffer that gradually transitions the lattice constant, reducing the sudden mismatch that causes strain and internal defects during the growth of long wavelength light emitting elements.
Solution Approach 2:
The patent changes the lattice constant parameter by introducing a semiconductor pattern layer with a specifically selected lattice constant that is greater than both the underlying substrate and the overlying semiconductor layer. This parameter modification creates a gradient structure that accommodates the lattice expansion needed for long wavelength emission while minimizing defect formation.
2Ease of manufacture
If the semiconductor layer has a small lattice constant to match the substrate, then manufacturing is easier, but strain accumulates during growth of long wavelength light emitting elements
Solution Approach 1:
The patent segments the interface between the substrate and the semiconductor layer by introducing a semiconductor pattern layer in between. This segmentation divides the lattice constant transition into two smaller steps (substrate to pattern layer, then pattern layer to semiconductor layer), reducing the strain accumulated in each individual interface while maintaining overall lattice compatibility.
3Area of stationary object
If the interface area between different lattice constant materials is increased, then more growth area is available, but more internal defects are generated
Solution Approach 1:
The semiconductor pattern layer is designed with specific local characteristics - it has a lattice constant greater than both the substrate and the semiconductor layer, creating a localized region of reduced strain. This local quality modification allows the interface area to be increased for greater growth area while the specific lattice constant of the pattern layer ensures that each unit of interface area generates fewer internal defects.
Data Source
AI summary
A display device includes a plurality of pixel electrodes spaced apart from each other on a substrate, a plurality of light emitting elements disposed on the plurality of pixel electrodes, the plurality of light emitting elements including a first semiconductor layer, a semiconductor pattern disposed on the first semiconductor layer, a common electrode layer disposed on the semiconductor pattern, and a void disposed between the first semiconductor layer, the semiconductor pattern, and the common electrode layer. The plurality of light emitting elements include a first light emitting element and a second light emitting element.