LED Active Layer Second Barrier Hole Injection

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Solution Overview

Problem

Current light emitting devices face challenges in achieving efficient hole injection and recombination in the active layer, leading to reduced light intensity and color purity, particularly due to the limitations in the band gap and thickness of barrier layers in nitride semiconductor-based LEDs.

Innovation Solution

The light emitting device incorporates a second barrier layer with a narrower band gap and less thickness than the other barrier layers, formed from an InGaN-based or AlGaN-based semiconductor layer, positioned between well layers to improve hole injection and recombination efficiency, enhancing light emission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional barrier layer structure with uniform band gap and thickness is used, then the device structure is simple and easy to manufacture, but hole injection and recombination efficiency is reduced

Engineering Contradiction:

Improvehole injection efficiencyVSAvoidbarrier layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a second barrier layer with different band gap and thickness parameters specifically positioned between the first and third barrier layers. This local modification creates a tailored potential well structure that enhances hole injection and recombination efficiency in the active region without requiring complete restructuring of the entire device

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent modifies the band gap and thickness parameters of the second barrier layer relative to the first and third barrier layers. By adjusting these physical parameters, the potential distribution in the active layer is optimized to improve carrier injection and recombination, directly addressing the efficiency problem

Inventive Principle:

Principle #35Parameter changes

2Reliability

If barrier layers with larger band gap and thickness are used, then carrier confinement is improved, but hole injection efficiency is reduced

Engineering Contradiction:

Improverecombination efficiencyVSAvoidenergy barrier for holes

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The second barrier layer acts as an intermediary structure between the first and third barrier layers. It mediates the potential distribution to create favorable conditions for hole injection while maintaining adequate carrier confinement, effectively bridging the contradiction between injection efficiency and confinement

Inventive Principle:

Principle #24Intermediary (Mediator)

3Illumination intensity

If the active layer structure is modified to improve light emission, then light intensity increases, but manufacturing complexity increases

Engineering Contradiction:

Improvelight intensityVSAvoidfabrication process

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The barrier layer structure is segmented into three distinct layers (first, second, and third barrier layers) with the second layer having different parameters. This segmentation allows independent optimization of each layer's properties to enhance light emission while maintaining a systematic fabrication approach

Inventive Principle:

Principle #1Segmentation

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 configuration increases the recombination efficiency within the active layer, resulting in improved light intensity and maintaining color purity by effectively guiding holes into the second well layer, thereby enhancing the overall light emission.

Implementation Method 1

the second barrier layer has the barrier height less than the barrier height of each of the first and third barrier layers

Methodology Applied

Scientific EffectBand gap energy difference:

Implementation Method 2

improve hole injection and recombination efficiency, enhancing light emission

Methodology Applied

Scientific EffectHole injection and recombination:

Implementation Method 3

Light emitting diodes (LEDs) are light emitting devices that convert an electric current into light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP2546892B1Light emitting device

Publication Date: 2018.09.19 LG INNOTEK CO LTD

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AI summary

A light emitting device is provided. The light emitting device comprises an active layer comprising a plurality of well layers and a plurality of barrier layers. The plurality of barrier layers comprise a first barrier layer which is the nearest to a second conductive type semiconductor layer, the first barrier layer having a first band gap, a second barrier layer adjacent to the first barrier, the second barrier layer having a third band gap, and at least one third barrier layer having the first band gap between the second barrier layer and a first conductive type semiconductor layer. The plurality of well layers comprise a first well layer between the first barrier layer and the second barrier layer, the first well layer having a second band gap, and a second well layer between the second barrier layer and the at least one third barrier layer. The second barrier layer is disposed between the first well layer and the second well layer, and the third band gap is narrower than the first band gap and wider than the second band gap.