Group III Nitride Semiconductor Light-Emitting Device Stress Relaxation

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Solution Overview

Problem

Conventional semiconductor light-emitting devices face reduced light quantity due to stress-induced distortion of the light-emitting layer, which decreases electron and hole recombination rates, and abnormal growth of semiconductor layers caused by pits.

Innovation Solution

A Group III nitride semiconductor light-emitting device is developed with an n-type semiconductor layer structure that includes an n-side electrostatic breakdown preventing layer and a superlattice layer, where the InGaN layers are alternately formed with specific In composition ratios and thicknesses to relax stress and suppress abnormal growth, enhancing crystallinity and radiant flux.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If pits are formed in the semiconductor layer to relax stress, then stress relaxation is improved, but abnormal growth of semiconductor layer occurs

Engineering Contradiction:

Improvestress applied to light-emitting layerVSAvoidabnormal growth of semiconductor layer

Core Design Contradiction:

Stress or pressureVSReliability

Solution Approach 1:

An n-side electrostatic breakdown preventing layer is introduced as an intermediary between the n-type contact layer and the light-emitting layer. This intermediate layer serves as the starting point for pit formation, allowing stress relaxation to occur while preventing abnormal growth in the light-emitting layer. The preventing layer acts as a buffer that absorbs the harmful effects of pit formation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The n-type semiconductor layer is segmented into multiple functional layers: an n-type contact layer, an n-side electrostatic breakdown preventing layer, and a light-emitting layer. By dividing the structure, the patent isolates the pit formation to the preventing layer, preventing propagation of abnormal growth to the light-emitting layer while maintaining stress relaxation benefits.

Inventive Principle:

Principle #1Segmentation

2Device complexity

If stress is applied to the light-emitting layer, then device structure is simplified, but light quantity is reduced due to decreased recombination rate

Engineering Contradiction:

Improvedevice structureVSAvoidlight quantity

Core Design Contradiction:

Device complexityVSIllumination intensity

Solution Approach 1:

The n-side electrostatic breakdown preventing layer is prepared in advance with controlled pit formation before the light-emitting layer is grown. This preliminary action creates a stress-relaxed substrate structure that prevents stress from being transferred to the light-emitting layer during subsequent growth, ensuring high recombination rate and light quantity from the outset.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10177276B2Group III nitride semiconductor light-emitting device and production method therefor

Publication Date: 2019.01.08 TOYODA GOSEI CO LTD

AI summary

There is provided a Group III nitride semiconductor light-emitting device exhibiting improved crystallinity while suppressing abnormal growth of semiconductor layer due to pits and a production method therefor. In forming an n-side electrostatic breakdown preventing layer, pits are generated from the n-side electrostatic breakdown preventing layer. In forming an n-side superlattice layer, the layer is formed by alternately depositing a first InGaN layer and a GaN layer having an In composition ratio lower than that of the first InGaN layer, so that the In composition ratio and the total thickness of the first InGaN layers satisfy the following equation: 0<Y≤180X+22, 0<X≤0.1, X: In composition ratio of InGaN layers, and Y: Total thickness of InGaN layers (nm).