UVA AlGaN Light-Emitting Layer Stack for Higher Output
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Solution Overview
Problem
There is a lack of reports on ultraviolet light-emitting elements with a central emission wavelength corresponding to UVA (above 320 nm), which are needed for applications such as resin curing, medicinal uses, and analytical purposes, and there is a demand for high light emission output in this wavelength range.
Innovation Solution
The ultraviolet light-emitting element comprises an n-type semiconductor layer, a quantum well-type light-emitting layer, a p-type electron blocking layer, a p-type cladding layer, and a p-type GaN contact layer, with specific Al composition ratios and thicknesses for each layer to achieve high light emission output with a central emission wavelength of more than 320 nm and less than 350 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thickness of the p-type contact layer is increased to improve flatness, then the flatness of the p-type contact layer is improved, but the total device thickness increases and manufacturing complexity increases
Solution Approach 1:
The patent divides the originally single thick p-type contact layer into multiple sub-layers with different Al compositions (AlGaN layers with varying Al content). This segmentation allows each sub-layer to contribute differently to the overall flatness while keeping the total thickness controlled, resolving the contradiction between achieving flatness and minimizing device complexity.
Solution Approach 2:
Different regions of the contact layer structure have different Al compositions tailored to specific functions: higher Al content in certain layers for better flatness control, lower Al content in others for electrical contact optimization. This local quality variation achieves the desired flatness without uniformly increasing the entire contact layer thickness.
2Reliability
If the Al composition ratio of the electron blocking layer is increased to improve electron blocking performance, then the electron blocking capability is improved, but the light emission output in the UVA region decreases
Solution Approach 1:
The patent optimizes the Al composition ratio parameter of the electron blocking layer to a specific range (0.35-0.45) that balances electron blocking performance with UVA light emission output. This parameter change resolves the contradiction by finding the optimal point where both requirements are satisfied simultaneously.
Solution Approach 2:
The patent uses AlGaN composite material with specifically controlled Al composition in the electron blocking layer, combining the benefits of electron blocking capability while maintaining transparency to UVA wavelengths, thus resolving the trade-off between reliability and productivity.
3Reliability
If the thickness of the electron blocking layer is increased to improve electron blocking performance, then the electron blocking capability is improved, but the light emission output and surface flatness deteriorate
Solution Approach 1:
The patent changes the thickness parameter of the electron blocking layer to an optimized range (11-70 nm) that provides sufficient electron blocking while maintaining good light emission output and surface flatness, resolving the contradiction between reliability and productivity.
4Reliability
If the total thickness of the electron blocking layer and cladding layer is increased to improve device performance, then the overall device performance is improved, but the manufacturing precision and surface flatness become more difficult to control
Solution Approach 1:
The patent segments the combined electron blocking layer and cladding layer into distinct sub-layers with specific thicknesses and Al compositions. This segmentation allows independent optimization of each layer's function while maintaining overall surface flatness and manufacturing precision, even with a total thickness that provides good device performance.
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 configuration enables high light emission output with a central emission wavelength of more than 320 nm and less than 350 nm, particularly more than 330 nm and less than 350 nm, effectively addressing the demand for UVA ultraviolet light-emitting elements.
Implementation Method 1
Light-emitting elements having aluminum gallium nitride (AlGaN) as a main constituent are capable of emitting light of approximately 250 nm to 360 nm
Data Source
AI summary
Provided are an ultraviolet light-emitting element that enables high light emission output and a method of producing the same. The light-emitting element (100) includes, in stated order: an n-type semiconductor layer (3) formed of AlxGa1-xN having an Al composition ratio x; a quantum well-type light-emitting layer (4); a p-type electron blocking layer (6) formed of AlyGa1-yN having an Al composition ratio y; a p-type cladding layer (7) formed of AlzGa1-zN having an Al composition ratio z; and a p-type GaN contact layer (8). The p-type electron blocking layer (6) has an Al composition ratio y of 0.35 to 0.45 and a thickness of 11 nm to 70 nm. The total thickness of the p-type electron blocking layer (6) and p-type cladding layer (7) is 73 nm to 100 nm. The thickness of the p-type GaN contact layer (8) is 5 nm to 15 nm.