Nanowire Excitonic Devices with Semi-Polar InGaN Quantum Disks

Solution Overview

Problem

Conventional microscale and nanoscale quantum well LEDs experience a significant reduction in efficiency when scaled down, primarily due to Shockley-Read-Hall recombination, Auger recombination, electron overflow/leakage, and enhanced surface recombination, with the exciton binding energy weakened by spontaneous and strain-induced polarization fields.

Innovation Solution

The development of submicron-scale nanowire excitonic devices with InGaN quantum disks that utilize semi-polar planes and nanoscale engineering to enhance exciton binding energy, incorporating indium-rich clusters and strain relaxation to improve electron-hole wavefunction overlap.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional quantum well LEDs are scaled down to microscale and nanoscale dimensions, then device size is reduced, but efficiency is significantly reduced

Engineering Contradiction:

Improvedevice sizeVSAvoidefficiency

Core Design Contradiction:

Volume of moving objectVSLoss of energy

Solution Approach 1:

The patent changes the crystal orientation parameter from conventional c-plane to semi-polar m-plane, which fundamentally alters the polarization field characteristics. This parameter change reduces the quantum-confined Stark effect and enhances exciton binding energy, enabling high efficiency at reduced device dimensions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces local compositional modulation with indium-rich clusters at specific positions within the quantum well structure. This local quality enhancement creates regions of increased exciton binding energy that compensate for surface recombination losses in nanoscale devices

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If conventional c-plane InGaN quantum well structures are used, then manufacturing is simpler, but exciton binding energy is weakened by polarization fields

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidexciton binding energy

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the crystal orientation parameter from conventional c-plane to semi-polar m-plane, which fundamentally alters the polarization field characteristics. This parameter change reduces the quantum-confined Stark effect and enhances exciton binding energy, enabling high efficiency at reduced device dimensions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure combining semi-polar InGaN quantum wells with specific indium composition gradients. This composite material approach creates regions with enhanced exciton binding energy while maintaining manufacturability through established epitaxial growth techniques

Inventive Principle:

Principle #40Composite materials

3Volume of moving object

If device size is reduced to submicron scale, then integration density is increased, but surface recombination losses are significantly enhanced

Engineering Contradiction:

Improvedevice sizeVSAvoidsurface recombination losses

Core Design Contradiction:

Volume of moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent introduces local compositional modulation with indium-rich clusters at specific positions within the quantum well structure. This local quality enhancement creates regions of increased exciton binding energy that compensate for surface recombination losses in nanoscale devices

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the harmful surface recombination effect into a beneficial design constraint by using the reduced device dimensions to create quantum confinement effects that enhance exciton binding energy. The same size reduction that increases surface-to-volume ratio also strengthens the quantum well confinement when combined with semi-polar orientation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

These devices achieve significantly enhanced exciton oscillator strength and efficiency, with external quantum efficiencies up to 25.2% and wall-plug efficiencies of 20.7%, surpassing conventional devices, and are suitable for applications in next-generation displays and optical interconnects.

Implementation Method 1

electrons and holes are spatially confined within an active region of each nanowire

Methodology Applied

Scientific EffectQuantum confinement: Potential Well

Implementation Method 2

The nanowires are operable for electroluminescent emission originating from excitons comprising bound states of electrons and holes in the active region

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 3

An exciton—a bound state of an electron and hole through strong Coulomb interaction—can drastically enhance the radiative recombination efficiency

Methodology Applied

Scientific EffectCoulomb interaction: Coulomb's Law

Data Source

PatentUS20250228040A1Ultrahigh efficiency excitonic device

Publication Date: 2025.07.10 THE RGT UNIV OF MICHIGAN

AI summary

An excitonic device includes a substrate and nanowires coupled to the substrate. Electrons and holes are spatially confined within an active region of each nanowire. The nanowires are operable for electroluminescent emission originating from excitons comprising bound states of electrons and holes in the active region of each nanowire.