LED Chip Barrier Regions Prevent Carrier Redistribution

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Solution Overview

Problem

Conventional white light-emitting diodes suffer from strong temperature dependency of color temperature and color coordinates, efficiency reduction, and 'droop' effects due to thermally activated carrier redistribution and increased non-radiative losses, limiting their performance and lifetime.

Innovation Solution

The light-emitting diode chip incorporates a semiconductor body with multiple active regions, each comprising subregions and barrier regions made of nitride compound semiconductor materials, where the barrier regions have a larger band gap than the subregions, preventing thermally activated carrier redistribution and allowing for independent photon generation ratios regardless of temperature and current density, thereby maintaining constant white light coordinates and suppressing 'droop' effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional white light-emitting diodes are used, then they can emit white light, but they suffer from strong temperature dependency of color temperature and color coordinates, efficiency reduction, and droop effects

Engineering Contradiction:

Improvethermal stability of color coordinatesVSAvoidefficiency reduction and droop effects

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The active region is divided into multiple subregions (first subregion, second subregion, third subregion) with different semiconductor materials having different band gaps. This segmentation allows each subregion to independently generate photons at specific wavelengths, preventing thermally activated carrier redistribution that causes color drift and efficiency loss in conventional LEDs.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different subregions are assigned different semiconductor materials with specific band gap energies tailored to their function. The first subregion uses material with band gap greater than the second, which in turn is greater than the third. This local differentiation of material properties enables precise control over photon generation in each region, maintaining stable color coordinates and suppressing droop effects.

Inventive Principle:

Principle #3Local quality

2Reliability

If barrier regions with larger band gap are introduced between subregions, then thermally activated carrier redistribution is prevented, but device structure becomes more complex

Engineering Contradiction:

Improvestability of photon generation ratioVSAvoidstructure of active region

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The active region is segmented into multiple subregions separated by barrier regions. Each subregion is bounded by barrier regions with larger band gaps, creating isolated zones for photon generation. This segmentation prevents carrier leakage and redistribution, ensuring stable photon generation ratios despite temperature variations or current density changes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Barrier regions act as intermediary structures between adjacent subregions. These barrier regions, having larger band gaps than the subregions they separate, serve as potential barriers that block thermally activated carrier redistribution while allowing optical photons to pass through. This intermediary structure maintains the independence of each subregion's photon generation process.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 design ensures stable white light emission with constant color coordinates and reduced efficiency losses across varying temperatures, enhancing the performance and lifetime of the light-emitting diodes by preventing thermally activated carrier redistribution and optimizing photon generation.

Implementation Method 1

preventing thermally activated carrier redistribution

Methodology Applied

Scientific EffectThermally activated carrier redistribution:

Implementation Method 2

each comprising subregions and barrier regions made of nitride compound semiconductor materials, where the barrier regions have a larger band gap than the subregions, preventing thermally activated carrier redistribution and allowing for independent photon generation ratios

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentEP2618388B1Light-emitting diode chip

Publication Date: 2019.10.02 OSRAM OPTO SEMICON GMBH & CO OHG

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Figure 2A~2C
Figure 3A~3B

AI summary

A light-emitting diode chip comprising: - a semiconductor body (1) having a plurality of active regions (2), wherein - at least one of the active regions (2) has at least two subregions (21...28), - the active region (2) has at least one barrier region (3) arranged between two adjacent subregions (21...28) of said at least two subregions (21...28), - the at least two subregions (21...28) emit light of mutually different colour during operation of the light-emitting diode chip, - in at least one of the subregions (21...28) the emission of light is generated electrically, and - the barrier region (3) is configured to hinder a thermally activated redistribution of charge carriers between the two adjacent subregions (21...28), is specified.