DUV LED Quantum Well Efficiency and Lifetime
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Solution Overview
Problem
Current deep ultraviolet light emitting diodes (DUV LEDs) face challenges in achieving high efficiency and long lifetime at wavelengths less than 360 nm, with low output power, low wallplug efficiency, and short device lifetime.
Innovation Solution
The development of semiconductor light emitting devices with a low defect density base structure, including a GaN layer doped with n-type dopants, a quantum well active region comprising GaN, AlGaN, or AlInGaN layers, and a doped AlGaN barrier layer, optimized to emit at wavelengths less than 360 nm with improved wallplug efficiency and extended direct current lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DUV LED structures are used, then device fabrication is simpler, but wallplug efficiency remains low and device lifetime is short
Solution Approach 1:
The device is divided into multiple functional layers including n-type GaN buffer layer, active region with quantum wells, p-type AlGaN cladding layers, and contact layers. Each layer is optimized independently to address specific performance requirements while managing complexity through functional segmentation.
Solution Approach 2:
The patent employs composite semiconductor structures combining GaN, AlGaN, and InGaN materials with different bandgaps and properties. This composite approach enables simultaneous optimization of light emission efficiency, carrier confinement, and device reliability at wavelengths less than 360 nm.
2Power
If conventional LED structures are used, then manufacturing is easier, but output power and wallplug efficiency are too low
Solution Approach 1:
The patent optimizes critical parameters including layer thicknesses (e.g., 5-20 nm quantum well layers), doping concentrations (e.g., 1e18 to 1e19 atoms/cm³), and material compositions (AlGaN with varying Al content). These parameter adjustments enable high output power while maintaining manufacturability through established epitaxial growth techniques.
Solution Approach 2:
n-type GaN buffer layers and p-type AlGaN cladding layers serve as intermediary structures that facilitate carrier injection, confinement, and extraction. These intermediate layers mediate between the active region and external contacts, improving overall device efficiency without requiring fundamentally new manufacturing processes.
3Use of energy by stationary object
If simple LED structures are used, then fabrication is easier, but wallplug efficiency remains low
Solution Approach 1:
The AlGaN cladding layers serve multiple functions simultaneously: optical confinement, electrical confinement, strain management, and defect filtering. This multi-functionality improves wallplug efficiency without proportionally increasing manufacturing complexity, as the same structural elements address multiple performance requirements.
Solution Approach 2:
The patent transitions from planar homojunction structures to vertically stacked heterostructure layers with quantum wells. This dimensional organization separates carrier injection, recombination, and extraction functions across different vertical zones, improving energy efficiency while maintaining compatibility with standard vertical epitaxial growth 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
The solution achieves wallplug efficiencies of at least 4% and direct current lifetimes of over 100 hours, with peak output wavelengths of 345 nm or less, significantly enhancing the performance of DUV LEDs in terms of efficiency and durability.
Implementation Method 1
a quantum well active region on the low defect density base structure that emits light at a wavelength of less than 360 nm
Data Source
AI summary
Light emitting devices and methods of fabricating light emitting devices that emit at wavelengths less than 360 nm with wall plug efficiencies of at least than 4% are provided. Wall plug efficiencies may be at least 5% or at least 6%. Light emitting devices and methods of fabricating light emitting devices that emit at wavelengths less than 345 nm with wall plug efficiencies of at least than 2% are also provided. Light emitting devices and methods of fabricating light emitting devices that emit at wavelengths less than 330 nm with wall plug efficiencies of at least than 0.4% are provided. Light emitting devices and methods of fabricating light emitting devices having a peak output wavelength of not greater than 360 nm and an output power of at least 5 mW, having a peak output wavelength of 345 nm or less and an output power of at least 3 mW and/or a peak output wavelength of 330 nm or less and an output power of at least 0.3 mW at a current density of less than about 0.35 μA/μm2 are also provided. The semiconductor light emitting devices may have a direct current lifetime of at least 100 hours, at least 500 hours or at least 1000 hours.