Crystallized IZO Transparent Electrode for UV Light Emission

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Solution Overview

Problem

Gallium nitride compound semiconductor light-emitting devices face challenges in achieving high emission power for ultraviolet light due to absorption by traditional transparent electrodes, such as ITO films, which reduce transmittance in the ultraviolet wavelength range.

Innovation Solution

A semiconductor light-emitting device with a crystallized IZO film transparent electrode is manufactured by forming an amorphous IZO film on a p-type semiconductor layer and undergoing an annealing process in a mixed gas atmosphere of N2 and H2, increasing transmittance in the ultraviolet range and reducing light absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transparent electrode absorbs ultraviolet light, then electrical conductivity is maintained, but emission power of ultraviolet light deteriorates

Engineering Contradiction:
Improveelectrical conductivityVSAvoidemission power of ultraviolet light
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The patent changes the material composition parameters by using IZO with optimized ZnO content (1-20 mass%) and controlling the amorphous/crystalline state through annealing temperature (500-900°C). These parameter changes reduce ultraviolet absorption while maintaining sufficient electrical conductivity, thereby increasing ultraviolet emission power.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent utilizes phase transition by annealing the amorphous IZO film at 500-900°C to transform it into a crystallized state. This phase transition modifies the material's optical absorption characteristics, reducing ultraviolet light absorption while preserving electrical conductivity, thus resolving the contradiction between conductivity and emission power.

Inventive Principle:
Principle #36Phase transitions

2Ease of manufacture

If amorphous IZO film is used, then manufacturing process is simplified, but ultraviolet light transmittance deteriorates

Engineering Contradiction:
Improvefilm formation processVSAvoidultraviolet light transmittance
Core Design Contradiction:
Ease of manufactureVSIllumination intensity

Solution Approach 1:

The patent applies preliminary action by performing annealing treatment at 500-900°C after film formation to crystallize the IZO. This preliminary crystallization step, done before device assembly, improves ultraviolet transmittance while the base film formation process remains simple and compatible with existing manufacturing techniques.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent exploits phase transition from amorphous to crystalline state through controlled annealing at 500-900°C. This phase transition enhances ultraviolet light transmittance by reducing absorption, while the process remains manufacturable as it uses standard thermal treatment equipment and temperature ranges suitable for semiconductor processing.

Inventive Principle:
Principle #36Phase transitions

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 use of a crystallized IZO film as a transparent electrode enhances ultraviolet light emission power by minimizing absorption, resulting in improved emission characteristics for semiconductor light-emitting devices and lamps.

Implementation Method 1

performing an annealing process at a temperature in the range of 500°C to 900°C to change the amorphous IZO film into a crystallized IZO film

Methodology Applied
Scientific EffectAnnealing: Annealing

Implementation Method 2

change the amorphous IZO film into a crystallized IZO film

Methodology Applied
Scientific EffectCrystallization: Crystallisation

Data Source

PatentEP2012371B1Method for fabricating a semiconductor light emitting device
Publication Date: 2015.02.25 TOYODA GOSEI CO LTD
  • EP2012371B1 patent drawingFigure 1~2
  • EP2012371B1 patent drawingFigure 3~4
  • EP2012371B1 patent drawingFigure 5

AI summary

The present invention provides a semiconductor light-emitting device capable of effectively emitting ultraviolet light and a method of manufacturing the same. A semiconductor light-emitting device 1 includes: a p-type semiconductor layer 14; a semiconductor layer that has an emission wavelength in at least an ultraviolet range; and a transparent electrode 15 that is formed on the p-type semiconductor layer 14. The transparent electrode 15 includes a crystallized IZO film.