InGaN/AlGaN Core-Shell Nanowire Emitters for Low-Threshold UV Emission
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Solution Overview
Problem
Existing semiconductor nanowire devices face challenges in realizing efficient electrically injected semiconductor lasers and light emitting diodes in the deep ultraviolet spectrum due to large bandgaps and effective masses, and conventional AlGaN materials have high thresholds, while surface recombination issues reduce output power in axial nanowire LEDs.
Innovation Solution
The formation of self-organized Ga(Al)N quantum dots and quantum wires with tunable InGaN/AlGaN core-shell quaternary nanowire heterostructures, where In-rich cores and Al-rich shells spontaneously form during growth, providing three-dimensional quantum confinement and reducing non-radiative surface recombination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional AlGaN materials are used for deep ultraviolet emitters, then the bandgap is sufficient for deep UV emission, but the large effective mass results in high lasing thresholds and reduced efficiency
Solution Approach 1:
The patent changes the dimensional parameters of the AlGaN structure by forming quantum wires and quantum dots with specific size ranges (quantum wires: 5-50 nm diameter, quantum dots: 3-15 nm diameter) to achieve three-dimensional quantum confinement. This parameter change reduces the effective mass and modifies the density of states, thereby reducing the lasing threshold while maintaining deep UV emission capability
Solution Approach 2:
The patent transitions from conventional two-dimensional quantum well structures to one-dimensional quantum wires and zero-dimensional quantum dots, creating three-dimensional quantum confinement. This dimensional change fundamentally alters the electronic structure and density of states, enabling low-threshold lasing in the deep UV regime
2Device complexity
If axial nanowire LED structures are used, then the device complexity is reduced, but surface recombination significantly reduces output power
Solution Approach 1:
The patent applies a shell structure surrounding the nanowire core, where the shell acts as a protective layer that passivates the nanowire surface. This shell configuration reduces surface recombination losses while maintaining the simplicity of the axial nanowire LED structure, thereby significantly enhancing output power
Solution Approach 2:
The shell structure serves as an intermediary layer between the nanowire core and the external environment, mediating the interaction by providing surface passivation. This intermediary layer reduces non-radiative recombination at the surface while allowing the simple axial structure to maintain its low complexity
3Use of energy by moving object
If InGaN/AlGaN core-shell quaternary nanowire heterostructures are formed with self-organization, then quantum confinement is achieved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs self-organized growth mechanisms where the InGaN/AlGaN core-shell heterostructures form spontaneously during the growth process without requiring precise external control of compositional gradients. The system self-organizes into quantum-confined structures, achieving high emission efficiency while reducing the manufacturing precision requirements compared to epitaxial growth methods
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 high efficiency ultraviolet emitters with reduced current density requirements, achieving low lasing thresholds and enhanced output power through Anderson localization and radial carrier confinement.
Implementation Method 1
providing three-dimensional quantum confinement and reducing non-radiative surface recombination
Implementation Method 2
The plurality of nanowires coherently emit optical radiation through the Anderson localization of light
Implementation Method 3
a shell structure surrounding the core structure establishing a radial carrier confinement
Data Source
AI summary
GaN-based nanowire heterostructures have been intensively studied for applications in light emitting diodes (LEDs), lasers, solar cells and solar fuel devices. Surface charge properties play a dominant role on the device performance and have been addressed within the prior art by use of a relatively thick large bandgap AlGaN shell covering the surfaces of axial InGaN nanowire LED heterostructures has been explored and shown substantial promise in reducing surface recombination leading to improved carrier injection efficiency and output power. However, these lead to increased complexity in device design, growth and fabrication processes thereby reducing yield/performance and increasing costs for devices. Accordingly, there are taught self-organising InGaN/AlGaN core-shell quaternary nanowire heterostructures wherein the In-rich core and Al-rich shell spontaneously form during the growth process.