LED Threading Dislocation Management via Dielectric Layer Openings
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Solution Overview
Problem
Threading dislocation defects in LED structures reduce luminous efficiency, particularly at the microscale, due to lattice mismatch and stress during epitaxial growth of crystalline materials with different lattice constants and thermal expansion coefficients.
Innovation Solution
Incorporating a dielectric layer with strategically positioned openings that expose parts of the semiconductor layer, allowing charge carriers to recombine in areas with lower threading dislocation density, thereby separating the light emitting area from threading dislocations and improving luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If threading dislocation defects are present in the LED structure due to epitaxial growth on mismatched substrates, then the LED can be manufactured with standard processes, but the luminous efficiency is reduced
Solution Approach 1:
The patent extracts and removes the harmful threading dislocation defects from the active region by creating openings in the dielectric layer that selectively expose semiconductor regions with threading dislocations. This allows the defective areas to be excluded from the light-emitting zone while preserving the overall device structure and manufacturing process.
Solution Approach 2:
The patent applies local quality by creating spatially selective regions with different functional properties. The dielectric layer with patterned openings creates distinct zones: areas with threading dislocations are excluded from light emission, while dislocation-free areas maintain high luminous efficiency. This local differentiation resolves the contradiction by allowing defective regions to coexist with high-performance regions.
2Loss of energy
If the opening in the dielectric layer is positioned to avoid threading dislocations, then luminous efficiency is improved, but the device structure becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-positioning the dielectric layer with strategically designed openings before final device assembly. The opening pattern is predetermined to align with and exclude threading dislocation regions, simplifying the manufacturing sequence while achieving the goal of separating defective from functional areas.
Solution Approach 2:
The dielectric layer serves as an intermediary element that mediates between the threading dislocation defects in the semiconductor layer and the electrode. By introducing this intermediate layer with controlled openings, the patent creates a buffer zone that excludes defects from the active region without requiring direct modification of the semiconductor or electrode structures.
3Ease of manufacture
If threading dislocations are present in the active layer, then the LED structure can be formed through standard epitaxial growth, but charge carrier recombination is reduced in high dislocation density areas
Solution Approach 1:
The patent segments the semiconductor layer into regions with different quality characteristics based on threading dislocation density. By introducing dielectric openings, it creates distinct functional segments: high recombination efficiency zones in dislocation-free areas and excluded zones in high dislocation density areas. This segmentation allows standard epitaxial growth to produce the layered structure while the opening pattern selectively activates only the high-efficiency regions for charge carrier recombination.
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 effectively enhances the luminous efficiency of LEDs by restricting current flow into areas with higher dislocation density, resulting in improved light emission characteristics, especially for micro-LEDs.
Implementation Method 1
Light emitting diodes (LEDs) are semiconductor light-emitting devices which convert electric current into light energy
Data Source
AI summary
A light-emitting diode (LED) includes a first type semiconductor layer, a second type semiconductor layer, an active layer, a dielectric layer and an electrode. The active layer disposed between the first type semiconductor layer and the second type semiconductor layer. The active layer has at least one threading dislocation therein. The dielectric layer is disposed on the second type semiconductor layer. The dielectric layer has at least one first opening therein to expose a part of the second type semiconductor layer. The vertical projection of the threading dislocation on the dielectric layer is separated from the first opening. The electrode partially disposed on the dielectric layer and electrically coupled with the exposed part of the second type semiconductor layer through the opening.