Stress Control Layer for UV LED Dislocation Reduction
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Solution Overview
Problem
The performance and reliability of ultraviolet (UV) light emitting diodes (LEDs) based on group III nitride semiconductor layers are hindered by high dislocation density and crack formation in semiconductor layers, which existing substrate patterning methods fail to adequately address, especially in large-scale production.
Innovation Solution
The introduction of stress control layers formed by epitaxially growing layers on patterned surfaces within the semiconductor heterostructure, which induce tensile or compressive stresses in adjacent layers, reducing dislocation density and crack formation by optimizing epitaxial growth over lattice mismatched substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If substrate patterning approaches are used to reduce stresses in epitaxially grown semiconductor layers, then dislocation density and crack formation are minimized, but manufacturing cost increases significantly for large-scale production
Solution Approach 1:
The patent introduces stress control layers as intermediary elements between the substrate and the semiconductor layers. These stress control layers mediate the stress distribution, allowing epitaxial growth on patterned substrates without requiring expensive substrate patterning. The stress control layers absorb and redistribute stresses, preventing dislocation formation while maintaining a simple substrate structure suitable for large-scale production.
Solution Approach 2:
The patent changes the physical and chemical parameters of the stress control layers, including their composition, thickness, and stress state (tensile or compressive). By adjusting these parameters, the stress control layers can be optimized to counteract specific stress conditions in the semiconductor layers, reducing dislocation density without requiring complex substrate patterning processes.
2Manufacturing precision
If stress control layers are introduced to reduce dislocation density, then semiconductor layer quality improves, but device structure complexity increases
Solution Approach 1:
The stress control layers are segmented into discrete regions with different stress characteristics. Rather than using a single complex patterned substrate, the patent divides the stress control function into multiple simpler layers with varying stress states, making the overall structure more manageable and easier to fabricate while maintaining high semiconductor layer quality.
3Productivity
If epitaxial growth is performed on lattice mismatched substrates, then production efficiency increases, but stress-induced defects increase without stress control layers
Solution Approach 1:
The stress control layers are prepared in advance during the epitaxial growth process, before the semiconductor layers are formed. This preliminary action of creating stress-controlled regions allows subsequent semiconductor layers to grow with reduced stress accumulation, enabling high-quality growth on lattice mismatched substrates without requiring post-growth stress relief processes.
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 stress control layers significantly reduce dislocation density and crack formation, enhancing the performance and reliability of UV LEDs by altering stress levels in adjacent layers, with induced stress changes extending into the interior of the semiconductor heterostructure, thereby improving the quality of semiconductor layers.
Implementation Method 1
The stress control layers can be formed by epitaxially growing the layers on the patterned surfaces in the semiconductor heterostructure
Implementation Method 2
Forming a stress control layer on a patterned surface enables the layer to induce tensile or compressive stresses to each adjacent layer in the semiconductor heterostructure
Data Source
AI summary
A semiconductor heterostructure for an optoelectronic device is disclosed. The semiconductor heterostructure includes at least one stress control layer within a plurality of semiconductor layers used in the optoelectronic device. Each stress control layer includes stress control regions separated from adjacent stress control regions by a predetermined spacing. The stress control layer induces one of a tensile stress and a compressive stress in an adjacent semiconductor layer.