HSG Buffer Layer for GaN Dislocation Reduction
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Solution Overview
Problem
Conventional solid-state lighting (SSL) devices, such as LEDs, suffer from high crystal lattice dislocations due to lattice mismatch between semiconductor materials and substrates, leading to impaired optical and electrical performance, including current leakage and low optical efficiency.
Innovation Solution
The formation of hemispherical grained silicon (HSG) structures on a substrate, followed by epitaxial growth of semiconductor materials, which reduces dislocation density by allowing lateral growth along specific axes and preventing dislocation propagation, thereby enhancing the crystal structure and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epitaxial growth is used to form GaN/InGaN materials on substrate, then semiconductor layers can be formed with controlled composition and structure, but a large number of threading dislocations are generated due to lattice mismatch
Solution Approach 1:
The patent applies preliminary action by forming a buffer layer structure before growing the active semiconductor layers. The buffer layer is deposited first to prepare the substrate surface and reduce dislocation propagation, then the GaN/InGaN layers are grown on top of this prepared structure, preventing dislocations from forming in the active regions.
Solution Approach 2:
The buffer layer acts as an intermediary between the substrate and the active GaN/InGaN semiconductor layers. This intermediate layer absorbs and mitigates the lattice mismatch stress, preventing threading dislocations from propagating into the active regions while still allowing the epitaxial growth of high-quality semiconductor layers.
2Productivity
If threading dislocations are present in semiconductor materials, then epitaxial growth can proceed on substrate, but optical efficiency decreases due to non-radiative recombination at dislocation cores
Solution Approach 1:
The patent extracts or removes threading dislocations from the active semiconductor regions by using a buffer layer structure that traps dislocations in the buffer layer while allowing dislocation-free growth in the active GaN/InGaN layers. This separation removes the harmful dislocation cores that cause non-radiative recombination.
Solution Approach 2:
The patent applies local quality by creating different structural characteristics in different regions: the buffer layer has a structure optimized for dislocation management, while the active GaN/InGaN layers have a structure optimized for high-quality optoelectronic performance. Each region is locally optimized for its specific function.
3Ease of manufacture
If threading dislocations are present in semiconductor materials, then epitaxial growth can proceed on substrate, but electrical performance deteriorates due to current leakage and P/N junction short circuits
Solution Approach 1:
The patent uses preliminary action by preparing the substrate with a buffer layer structure before growing the active semiconductor layers. This preliminary buffer layer structure prevents dislocation propagation into the active regions, ensuring high electrical performance in the final device while maintaining ease of manufacture through standard epitaxial 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
This approach significantly decreases dislocation density in SSL devices, improving their optical and electrical performance by minimizing defects and enhancing operational efficiency.
Implementation Method 1
epitaxial growth of semiconductor materials, which reduces dislocation density by allowing lateral growth along specific axes
Data Source
AI summary
Solid state lighting devices and associated methods of manufacturing are disclosed herein. In one embodiment, a solid state lighting device includes a substrate material having a substrate surface and a plurality of hemispherical grained silicon (“HSG”) structures on the substrate surface of the substrate material. The solid state lighting device also includes a semiconductor material on the substrate material, at least a portion of which is between the plurality of HSG structures.