Nitride Semiconductor Light Emitting Device Multilayer Electron Injection

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Solution Overview

Problem

Nitride semiconductor light emitting devices face challenges with stress and defect propagation due to complex stack structures, leading to reduced light emitting efficiency and reliability.

Innovation Solution

A nitride semiconductor light emitting device with a multilayer electron injection layer having three or more layers with different energy band gaps, stacked repetitively, which relieves stress and reduces defect occurrence by facilitating current injection and improving crystal quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a super lattice layer and electron ejection layer are stacked for current diffusion and stress relief, then current distribution is improved, but device complexity and defect occurrence increase

Engineering Contradiction:

Improvecurrent distributionVSAvoidstack structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The electron injection layer is divided into multiple sub-layers with different band gaps (first electron injection layer with larger band gap, second electron injection layer with smaller band gap). This segmentation allows each sub-layer to perform specific functions: the first layer provides stress relief and defect filtering, while the second layer enhances electron injection efficiency. By dividing the injection function across specialized sub-layers, the patent achieves better current distribution without requiring a complex super-lattice structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the electron injection layer are assigned different material compositions and band gap characteristics. The first electron injection layer (closer to the n-type layer) has a larger band gap for stress management, while the second electron injection layer (closer to the active layer) has a smaller band gap for optimized electron injection. This local differentiation of material properties allows simultaneous optimization of stress relief and electron injection without increasing overall structural complexity.

Inventive Principle:

Principle #3Local quality

2Reliability

If multiple layers with different band gaps are stacked for electron injection, then light emitting efficiency is improved, but stress and defect occurrence increase

Engineering Contradiction:

Improvelight emitting efficiencyVSAvoidstress and defects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The first electron injection layer with larger band gap is positioned between the n-type GaN layer and the second electron injection layer to preliminarily filter dislocations and relieve stress before electrons reach the active layer. This preliminary action of defect filtering and stress management prevents harmful factors from propagating into the active layer, thereby maintaining high light emitting efficiency without the adverse effects of accumulated stress and defects.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent employs a composite structure of GaN and AlGaN layers with different band gaps within the electron injection region. The GaN layers provide low defect density and good lattice matching, while AlGaN layers provide higher band gaps for stress relief. This composite material approach combines the advantages of different materials to simultaneously achieve stress relief, defect reduction, and efficient electron injection, thereby improving light emitting efficiency without increasing stress and defect occurrence.

Inventive Principle:

Principle #40Composite materials

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 solution enhances current distribution, light emitting efficiency, and reliability by reducing defects and simplifying the semiconductor structure, thereby improving productivity and luminance.

Implementation Method 1

the electron injection layer has a multilayer structure, in which three or more layers having different energy band gaps are stacked

Methodology Applied

Scientific EffectEnergy band gap gradient:

Implementation Method 2

improving electron transport and current injection

Methodology Applied

Scientific EffectElectron transport:

Implementation Method 3

an electron injection layer relieving stress from a nitride layer

Methodology Applied

Scientific EffectStress relief: Stress Relaxation

Data Source

PatentUS8643037B2Nitride semiconductor light emitting device

Publication Date: 2014.02.04 SAMSUNG ELECTRONICS CO LTD

AI summary

There is provided a nitride semiconductor light emitting device including: n-type and p-type nitride semiconductor layers; an active layer disposed between the n-type and p-type nitride semiconductor layers; and an electron injection layer disposed between the n-type nitride semiconductor layer and the active layer. The electron injection layer has a multilayer structure, in which three or more layers having different energy band gaps are stacked, and the multilayer structure is repetitively stacked at least twice. At least one layer among the three or more layers has a reduced energy band gap in individual multilayer structures in a direction toward the active layer, and the layer having the lowest energy band gap has an increased thickness in individual multilayer structures in a direction toward the active layer.