AlGaN Heterostructure Charge-Sheet Design for UVC LED Conductivity
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Solution Overview
Problem
Al-richer AlGaN materials in UVC LEDs face challenges with electrical conduction due to increasing donor and acceptor activation energies, leading to a deficiency of free electron and hole carriers, which affects the efficiency and reliability of the devices.
Innovation Solution
The design of AlGaN heterostructures with p-type doped layers containing sheets of positive charge, where the distance between adjacent sheets is larger than the depletion depth, and the use of alternately stacked p-type doped AlGaN barriers and wells with specific thickness and Al-composition profiles to enhance dopant activation and carrier confinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Al-richer AlGaN materials are used to achieve UVC emissions, then the UV light intensity and germicidal effect are improved, but the electrical conductivity deteriorates due to increasing donor and acceptor activation energies
Solution Approach 1:
The patent segments the AlGaN structure into multiple quantum wells separated by barriers, creating a superlattice structure. This segmentation allows the material to maintain high Al-composition for UVC emission while the quantum well confinement and barrier design compensate for the reduced electrical conductivity through enhanced carrier concentration in the wells.
Solution Approach 2:
The patent changes the structural parameters by introducing quantum wells with specific thicknesses and Al-compositions, and by optimizing barrier thicknesses. These parameter changes enable the system to achieve UVC emission at 278 nm while maintaining electrical conductivity through proper carrier confinement and activation in the quantum wells.
2Stability of the object's composition
If AlN/AlGaN superlattice is used for dislocation and strain management, then the material quality is improved, but the device complexity increases
Solution Approach 1:
The AlN/AlGaN superlattice structure serves multiple functions simultaneously: it manages dislocations, controls strain, and provides quantum confinement for carrier injection. This multi-functionality reduces the need for separate structural elements, thereby managing complexity while achieving high material quality.
Solution Approach 2:
The patent uses composite AlN/AlGaN superlattice structures combining materials with different properties. The AlN layers provide mechanical stability and dislocation management, while AlGaN layers provide the necessary bandgap for UVC emission, creating a composite structure that achieves both material quality and functional requirements.
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 improves the electrical conductivity and quantum confinement, leading to enhanced dopant activation, increased carrier accumulation, and improved reliability and efficiency of UVC LEDs by optimizing the thickness and Al-composition of the heterostructure layers.
Implementation Method 1
one or more sheets of positive charge inserted therein, wherein a distance between two adjacent sheets of positive charge is larger than a depletion depth of a depletion zone generated by any one of the two adjacent sheets of positive charge
Implementation Method 2
design rules for AlGaN heterostructures of improved conductivity and quantum confinement in regard to dopant concentration and interface charge density
Data Source
AI summary
Heterostructures containing one or more sheets of positive charge, or alternately stacked AlGaN barriers and AlGaN wells with specified thickness are provided. Also provided are multiple quantum well structures and p-type contacts. The heterostructures, the multiple quantum well structures and the p-type contacts can be used in light emitting devices and photodetectors.