Quantum Dot Trap Region for Hot Carrier Management

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Solution Overview

Problem

Semiconductor quantum dots face limited conversion efficiency at higher pump flux levels due to multi-carrier Auger processes generating hot carriers that can lead to surface degradation and photoionization, reducing their optical performance.

Innovation Solution

Incorporating a trap region with a band edge configuration that traps hot carriers, preventing them from reaching the surface and enhancing the quantum dot structure with a barrier region and active region configuration that absorbs primary radiation while ensuring the trap region does not quench excitation, allowing charge carriers to recombine radiatively in the active region.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If quantum dots are used for optical down conversion, then radiation conversion is achieved, but conversion efficiency is limited at higher pump flux levels

Engineering Contradiction:

Improveconversion efficiencyVSAvoidperformance stability at high pump flux

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The quantum dot structure is segmented into distinct functional regions: an active region for radiative recombination, a barrier region to confine carriers, and a trap region to manage hot carriers. This segmentation allows each region to perform its specific function optimally, preventing hot carrier damage while maintaining high conversion efficiency at elevated pump flux levels

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The trap region acts as an intermediary between the active region and the surface, capturing hot carriers before they can reach and damage the surface. This intermediary structure protects the quantum dot from harmful effects while maintaining the benefits of high pump flux operation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Power

If multi-carrier Auger processes occur at high pump flux, then radiation conversion continues, but hot carriers cause surface degradation and photoionization

Engineering Contradiction:

Improveradiation conversion capabilityVSAvoidsurface degradation

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The trap region converts the harmful hot carriers generated by Auger processes into a beneficial protective mechanism. By capturing these hot carriers, the trap region prevents surface degradation and photoionization, transforming what was previously a harmful effect into a protective function that enhances overall device reliability

Inventive Principle:

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

Solution Approach 2:

The trap region serves as a protective intermediary layer that intercepts hot carriers before they can reach the surface. This mediator structure allows the quantum dot to maintain high power radiation conversion capability while protecting against the harmful effects of hot carrier accumulation

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If a trap region is added to capture hot carriers, then surface degradation is reduced, but device structure becomes more complex

Engineering Contradiction:

Improveresistance to surface degradationVSAvoidquantum dot structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The trap region is strategically positioned only where needed - between the active region and the surface - rather than throughout the entire quantum dot structure. This localized approach provides the necessary protection against surface degradation while minimizing the increase in overall device complexity

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The trap region is nested within the quantum dot structure, fitting between the active region and the surface in a space-efficient manner. This nested configuration allows the protective function to be integrated into the existing structure without significantly increasing overall device complexity

Inventive Principle:

Principle #7Nested doll (Nesting)

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 trap region effectively captures hot carriers, reducing surface degradation and enhancing conversion efficiency, especially at high pump flux levels, by ensuring charge carriers recombine in the active region, thus improving the quantum dot structure's performance.

Implementation Method 1

The barrier region is in particular configured to absorb a primary radiation which is to be converted into the radiation to be emitted by the active region

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

charge carriers recombine radiatively in the active region

Methodology Applied

Scientific EffectRadiative recombination: Luminescence

Implementation Method 3

a band edge of the trap region forms a trap configuration with respect to the barrier region for at least one type of charge carriers

Methodology Applied

Scientific EffectCarrier trapping: Potential Well

Data Source

PatentUS11557686B2Quantum dot structure having a barrier region and a trap region, radiation conversion element and light-emitting device

Publication Date: 2023.01.17 OSRAM OPTO SEMICON GMBH & CO OHG

AI summary

A quantum dot structure, a radiation conversion element and a light emitting device are disclosed. In an embodiment a quantum dot structure includes an active region configured to emit radiation, a barrier region surrounding the active region and a trap region spaced apart from the active region, wherein a band edge of the trap region forms a trap configuration with respect to the barrier region for at least one type of charge carrier.