III-Nitride Quantum Well With Cubic GaN Buffer
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Solution Overview
Problem
Conventional III-nitride quantum well structures face limitations in performance and waveband due to lattice mismatch and volatility of indium, restricting the growth of high-quality InGaN epitaxial layers with over 20% indium content, which limits the range of visible light emission.
Innovation Solution
A III-nitride quantum well structure is formed by growing an InGaN alloy layer with greater than 20% indium content between a GaN base and a GaN covering layer, using a PAMBE system to improve lattice matching and light-emitting efficiency, allowing for the production of light-emitting elements with various wavelengths of visible light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PAMBE mechanism is used to grow InGaN epitaxial layer under low temperature, then indium volatility is reduced, but lattice mismatch between substrate and epitaxial layer limits the indium content to less than 20%
Solution Approach 1:
The patent introduces a cubic GaN buffer layer as an intermediary between the substrate and the wurtzite InGaN epitaxial layer. This buffer layer serves as a transition structure that improves lattice matching and reduces dislocation density, enabling the growth of high-quality InGaN layers with indium content exceeding 20% that would otherwise be impossible to achieve directly on conventional substrates.
Solution Approach 2:
The patent changes the crystal structure parameter of the GaN buffer layer from the conventional wurtzite structure to a cubic structure. This parameter change in the buffer layer's crystal structure allows for better lattice matching with the InGaN epitaxial layer, enabling higher indium content while maintaining layer quality and achieving broader visible light emission ranges.
2Adaptability or versatility
If indium content in InGaN is increased to expand visible light waveband, then light-emitting efficiency is improved, but indium volatility under high temperature makes it difficult to grow large area uniform epitaxial film
Solution Approach 1:
The patent performs preliminary action by growing the cubic GaN buffer layer before depositing the InGaN epitaxial layer. This buffer layer is prepared in advance to establish a suitable crystal structure foundation that can support high-indium-content InGaN growth without suffering from indium volatility, thereby enabling uniform large-area epitaxial films with expanded waveband coverage.
Solution Approach 2:
The cubic GaN buffer layer acts as an intermediary that mediates between the substrate and the high-indium-content InGaN layer. It provides a stable crystal structure foundation that compensates for the instability caused by indium volatility, allowing uniform epitaxial growth across large areas while maintaining high indium content for expanded visible light emission.
3Adaptability or versatility
If indium content is increased to achieve broader visible light emission, then light-emitting element performance is improved, but lattice mismatch between GaN and InN prevents high-quality InGaN quantum well formation
Solution Approach 1:
The cubic GaN buffer layer serves as an intermediary structure that mitigates the lattice mismatch between GaN and high-indium-content InGaN. By providing a transitional crystal structure, it enables the formation of high-quality quantum well structures with indium content sufficient to achieve broader visible light emission while maintaining structural reliability.
Solution Approach 2:
The patent changes the crystal structure parameter of the buffer layer to cubic GaN, which has different lattice constants compared to conventional wurtzite GaN. This parameter change allows for better lattice matching with InGaN layers containing high indium content, enabling the formation of reliable quantum well structures that emit across a broader visible spectrum.
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 enables the production of high-quality light-emitting elements with a broader range of visible light emission, enhancing light-emitting efficiency and overcoming the limitations of conventional III-nitride quantum well structures.
Implementation Method 1
the conventional plasma-assisted molecular beam epitaxy (PAMBE) mechanism is used to grow the epitaxial layer of indium gallium nitride (InxGa1-xN)
Data Source
AI summary
An III-nitride quantum well structure includes a GaN base, an InGaN layer and an InGaN covering layer. The GaN base includes a GaN buffering layer, a GaN post extending from the GaN buffering layer, and a GaN pyramid gradually expanding from the GaN post to form a mounting surface. The InGaN layer includes first and second coupling faces. The first coupling face is coupled with the mounting surface. The GaN covering layer includes first and second coupling faces. The first coupling face of the GaN covering layer is coupled with the second coupling face of the InGaN layer.