III-Nitride Strain-Relaxed Template for High-Indium Green Emitters

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

III-nitride-based green light-emitting diodes (LEDs) and laser diodes (LDs) face challenges due to high lattice mismatch, leading to strain, defects, and reduced indium incorporation, which affects their efficiency and output power.

Innovation Solution

The method involves growing III-nitride-based devices on or above a strain relaxed template (SRT) using a thin, thermally decomposed InGaN underlayer and a n-type GaN or low indium composition InGaN decomposition stop layer, followed by an n-type InGaN/GaN superlattice buffer layer and subsequent layers optimized for high indium incorporation and reduced strain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If III-nitride-based devices are grown on conventional substrates without strain relaxation, then the device structure remains simple, but high lattice mismatch causes strain, defects, and reduced indium incorporation, degrading efficiency and output power

Engineering Contradiction:

Improvedevice structure simplicityVSAvoidcrystal quality and device performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The device structure is segmented into multiple functional layers: a strain-relaxed template layer ( comprising InGaN quantum wells and GaN barriers), an InGaN buffer layer, and the active device region. This segmentation allows the template layer to specifically address strain relaxation while maintaining simplicity in the overall fabrication process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A strain-relaxed template is grown preliminarily before the active device region. This template includes InGaN quantum wells with higher indium content that relax strain through controlled defect formation, preparing the substrate for subsequent high-quality indium incorporation in the active region without causing harmful strain accumulation.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If higher indium incorporation is attempted to improve green light emission, then the efficiency and output power increase, but lattice mismatch and strain increase, causing defects and reducing crystal quality

Engineering Contradiction:

Improveindium incorporation efficiencyVSAvoidcrystal quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

Different regions of the device have different indium compositions optimized for their specific functions. The template layer contains InGaN quantum wells with higher indium content (e.g., In0.15Ga0.85N) for strain relaxation, while the active region maintains controlled indium incorporation for efficient green light emission without excessive strain.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The indium composition parameter is varied across different layers. The template layer uses higher indium content to induce strain relaxation through controlled defects, while the active region uses optimized indium content for efficient green emission. Growth temperature and other parameters are also adjusted to control indium incorporation and strain management.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If strain is reduced through relaxed buffer layers, then indium incorporation and device efficiency improve, but the device structure and fabrication process become more complex

Engineering Contradiction:

Improveindium incorporation and device efficiencyVSAvoidstructure and process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The structure is divided into a template section (with strain-relaxing InGaN/GaN superlattice) and an active device section. This segmentation allows strain relaxation to be achieved in a dedicated layer without complicating the active region structure, maintaining fabrication simplicity while improving indium incorporation and device efficiency.

Inventive Principle:

Principle #1Segmentation

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 approach enhances the crystal quality, allows for higher indium incorporation, and improves the efficiency and output power of green LEDs and LDs, achieving higher wall-plug efficiency and continuous wave output.

Implementation Method 1

a thin, thermally decomposed InGaN underlayer

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Data Source

PatentUS20250133866A1Iii-nitride-based high efficiency and high-power devices grown on or above a strain relaxed template

Publication Date: 2025.04.24 RGT UNIV OF CALIFORNIA

AI summary

A method of growing III-nitride-based devices, such as light emitting diodes (LEDs) and laser diodes (LDs) on or above a strain relaxed template (SRT). The SRT uses a thin, thermally decomposed, InGaN underlayer, which is referred to as a decomposition layer (DL). Above the DL is a n-type GaN or low composition InGaN decomposition stop layer (DSL). A buffer layer comprising an n-type InGaN/GaN superlattice (SL) is then grown. For an LD structure. an n-type waveguide layer comprising a second n-type InGaN/GaN SL is then grown. followed by an active region, a p-type electron blocking layer (EBL), a p-type waveguide layer comprising a p-type InGaN/GaN SL, and p-type GaN or p-type InGaN layers. For an LED structure, the waveguide layers may be omitted. In this disclosure, AlGaN means AlxGa(1-x)N with 1≥x≥0 and InGaN means InxGa(1-x)N with 1≥x≥0.