Patterned InGaN Seed Regions for Multi-Wavelength Relaxed Epitaxy
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Solution Overview
Problem
Current methods for growing high-quality, relaxed InGaN layers for optoelectronic devices face challenges due to severe strain and poor material quality, leading to compromised performance in LEDs and laser diodes, as existing techniques result in high defect densities and limited lattice dilation, making it difficult to achieve variable composition InGaN alloys with different in-plane a-lattice parameters on the same growth substrate.
Innovation Solution
A semiconductor structure is developed with a substrate having patterned InGaN seed regions, allowing for the growth of InGaN layers with varying in-plane a-lattice parameters, enabling the formation of relaxed InGaN regions that can serve as a growth surface for other semiconductor materials, facilitating the fabrication of multi-color optoelectronic devices with improved material quality and reduced strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If InGaN active layers with different InN content are grown on GaN substrate, then multi-wavelength emission is achieved, but severe strain and poor material quality occur due to lattice mismatch
Solution Approach 1:
The patent segments the growth process into multiple stages: first growing a GaN buffer layer, then sequentially growing InGaN layers with different InN compositions (x values) on the same GaN substrate. Each InGaN layer is grown with composition tailored for specific wavelength emission, enabling multi-color devices while managing strain through compositional grading and layer thickness control.
Solution Approach 2:
The patent applies local quality by varying the InN composition (x parameter) at different vertical positions within the InGaN active layers. Each layer has a specific composition optimized for its intended emission wavelength, allowing different regions of the device to have locally optimized properties for red, green, or blue emission while maintaining overall device functionality.
2Adaptability or versatility
If the in-plane a-lattice parameter is altered to achieve variable composition InxAlyGa1-x-yN alloys, then high-density multi-wavelength emitters are enabled, but growth defect generation increases
Solution Approach 1:
The patent systematically changes the compositional parameters (x, y, and z values in InxAlyGa1-x-yN) to achieve different in-plane a-lattice parameters. By precisely controlling the In, Al, and Ga ratios during molecular beam epitaxy growth, the patent achieves variable composition alloys with tailored lattice parameters while minimizing growth defects through optimized growth conditions and sequential layer deposition.
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 enables the growth of high-quality, relaxed InGaN layers with varying in-plane a-lattice parameters, reducing defect densities and enhancing the performance of optoelectronic devices by allowing for the realization of multi-color emitters with improved material quality and reduced strain, thereby addressing the limitations of existing techniques.
Implementation Method 1
InxAlyGa1-x-yN grown on the patterned seed regions relaxes and subsequently coalesces to provide substantially relaxed (0001) InxAlyGa1-x-yN growth regions
Data Source
AI summary
InxAlyGa1-x-yN semiconductor structures having optoelectronic elements characterized by epitaxial layers having different in-plane a-lattice parameters and different InN mole fractions are disclosed. The active regions are configured to emit radiation in different wavelength ranges and are characterized by strain states within about 1% to 2% of compressive strain. The epitaxial layers are grown on patterned InxAlyGa1-x-yN seed regions on a single substrate, where the relaxed InGaN growth layers provide (0001) InxAlyGa1-x-yN growth surfaces characterized by different in-plane a-lattice parameters and different InN mole fractions. InxAlyGa1-x-yN semiconductor structures can be used in optoelectronic devices such as in light sources for illumination and in display applications.