Reflective Layer Embedded in Semiconductor for Light Extraction

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Solution Overview

Problem

Conventional light-emitting devices face inefficiencies in light extraction due to light absorption by semiconductor layers, which reduces the overall light extraction efficiency.

Innovation Solution

Incorporating a reflective layer within the second conductivity type semiconductor layer, positioned close to the active layer, to effectively reflect light emitted from the active layer and minimize absorption, thereby enhancing light extraction efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If light is emitted from the active layer through the second conductivity type semiconductor layer, then light can be extracted from the device, but the semiconductor layer absorbs part of the light which reduces light extraction efficiency

Engineering Contradiction:
Improvelight absorption lossVSAvoidlight extraction efficiency
Core Design Contradiction:
Loss of energyVSProductivity

Solution Approach 1:

The patent converts the harmful light absorption effect of the second conductivity type semiconductor layer into a beneficial reflection effect by forming a reflective layer within it. The reflective layer, positioned close to the active layer, reflects light that would otherwise be absorbed, converting the loss mechanism into a light extraction enhancement mechanism.

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

Solution Approach 2:

The reflective layer acts as an intermediary between the active layer and the second conductivity type semiconductor layer. It mediates the interaction between emitted light and the semiconductor layer by reflecting light back toward the extraction path, preventing direct absorption while maintaining the electrical function of the semiconductor layer.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If a reflective layer is embedded within the second conductivity type semiconductor layer, then light extraction efficiency is improved, but the device structure becomes more complex

Engineering Contradiction:
Improvelight extraction efficiencyVSAvoiddevice structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges the reflective layer formation process with the existing semiconductor layer growth process. The reflective layer is formed within the second conductivity type semiconductor layer during the same fabrication sequence, combining multiple functions into a single integrated structure rather than adding separate components.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The second conductivity type semiconductor layer serves multiple functions: it provides electrical conduction, structural support, and now also contains an embedded reflective layer for light extraction enhancement. This multi-functionality reduces the need for additional separate components, simplifying the overall device structure despite the added functionality.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 reflective layer significantly reduces light absorption in the semiconductor layer, leading to improved light extraction efficiency and increased brightness of the light-emitting device.

Implementation Method 1

Incorporating a reflective layer within the second conductivity type semiconductor layer, positioned close to the active layer, to effectively reflect light emitted from the active layer

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2860773B1Light-emitting device, and light-emitting device package
Publication Date: 2019.10.09 LG INNOTEK CO LTD
  • EP2860773B1 patent drawingFigure 1~3
  • EP2860773B1 patent drawingFigure 4~5
  • EP2860773B1 patent drawingFigure 6~7

AI summary

A light-emitting device, according to one embodiment, comprises: a light-emitting structure comprising a first conductive semiconductor layer, an active layer which is underneath the first conductive semiconductor layer, and a second conductive semiconductor layer which is underneath the active layer; a first electrode which is arranged under the light-emitting structure and is electrically connected to the second conductive semiconductor layer; a reflection layer which is arranged inside the second conductive semiconductor layer and arranged apart from the first electrode and the active layer; and a second electrode which is electrically connected to the first conductive semiconductor layer.