AlGaN Multilayer UV Emitters for Higher Radiative Recombination

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current UV LEDs are inefficient and expensive compared to Mercury vapor lamps, hindering their adoption for disinfection and other applications, and face challenges in achieving high radiative carrier recombination due to material growth issues with AlGaN.

Innovation Solution

Incorporating a novel doped multilayer structure adjacent to the active region of UV LEDs, comprising alternating layers of AlGaN with varying aluminum compositions, to enhance radiative recombination and light output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional AlGaN material structure is used in UV LEDs, then device simplicity is maintained, but radiative recombination efficiency is insufficient

Engineering Contradiction:

Improveradiative recombination efficiencyVSAvoidmaterial layer structure complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent divides the n-type AlGaN layer into multiple thin alternating layers with different aluminum compositions (e.g., Al0.6Ga0.4N and Al0.7Ga0.3N) instead of using a single uniform layer. This segmentation creates multiple interfaces that enhance radiative recombination while maintaining overall structural organization.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the n-type layer are assigned different aluminum compositions locally. The higher aluminum composition regions provide stronger confinement and higher radiative recombination, while lower aluminum composition regions facilitate carrier transport, creating local optimization throughout the layer.

Inventive Principle:

Principle #3Local quality

2Productivity

If higher aluminum composition AlGaN layers are used to improve radiative recombination, then light output efficiency increases, but material growth difficulty increases

Engineering Contradiction:

Improvelight output powerVSAvoidepitaxial growth ease

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

Instead of growing a single thick layer with high aluminum composition that would be difficult to grow uniformly, the patent segments it into multiple thin alternating layers with varying compositions. This makes the epitaxial growth process more manageable and reduces defects while maintaining high light output.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent varies the aluminum composition parameter locally within the n-type layer, creating alternating regions of Al0.6Ga0.4N and Al0.7Ga0.3N. This parameter variation allows optimization of both growth conditions and optical performance, as lower aluminum layers grow more easily while higher aluminum layers provide better radiative recombination.

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If conventional single-layer n-type structure is used, then manufacturing process is simple, but energy efficiency is low

Engineering Contradiction:

Improveenergy efficiencyVSAvoidn-type layer structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The conventional single-layer n-type structure is segmented into multiple thin alternating layers with different aluminum compositions. This segmentation creates additional interfaces that reduce non-radiative recombination losses and improve overall energy efficiency by directing more carriers toward radiative recombination pathways.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates a composite structure within the n-type layer by combining AlGaN layers with different aluminum compositions (Al0.6Ga0.4N and Al0.7Ga0.3N) in an alternating pattern. This composite approach leverages the advantages of both compositions to reduce energy loss while maintaining structural integrity.

Inventive Principle:

Principle #40Composite materials

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

Significantly improves the energy efficiency and output power of UV LEDs, making them more competitive with traditional lamps and enabling broader commercial applications.

Implementation Method 1

enhance radiative recombination and light output

Methodology Applied

Scientific EffectRadiative recombination: Electroluminescence

Data Source

PatentUS20230369538A1High efficiency ultraviolet light-emitting devices incorporating a novel multilayer structure

Publication Date: 2023.11.16 RGT UNIV OF CALIFORNIA

AI summary

A multilayer structure comprising regions of higher aluminum (Al) composition as compared to adjacent layers, in combination with an undulating active region and controlled buffer layer crystal quality, promotes radiative recombination and improves the performance and efficiency of ultraviolet (UV) or far-UV light-emitting diodes (LEDs), laser diode (LDs), or other light emitting devices.