InGaN Quantum Well Light-Emitting Structure for Piezoelectric Field Management
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Solution Overview
Problem
In light-emitting structures with indium gallium nitride quantum wells, the high piezoelectric fields at heterojunctions between quantum wells and barrier layers hinder efficient charge carrier injection, making it difficult to construct structures with multiple quantum wells and achieving high radiation efficiency.
Innovation Solution
A light-emitting structure is designed with a p-doped region and an n-doped region, featuring InGaN quantum wells of two types: low indium content quantum wells for reduced piezoelectric fields and high indium content quantum wells adjacent to the p-doped region, with controlled doping and barrier layers to enhance charge carrier injection and emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of quantum wells is increased to improve light emission, then the radiation efficiency is improved, but the potential barriers at heterojunctions increase making charge carrier injection more difficult
Solution Approach 1:
The patent applies local quality by creating two distinct types of quantum wells with different indium contents positioned at different locations within the active region. Quantum wells with lower indium content (first type) are placed adjacent to the n-doped region where electron injection occurs, while quantum wells with higher indium content (second type) are placed adjacent to the p-doped region where hole injection occurs. This spatial differentiation of material composition allows each quantum well type to be optimized for its specific location's charge carrier injection requirements, resolving the contradiction between achieving high radiation efficiency through multiple quantum wells and managing the potential barriers that hinder carrier injection.
2Illumination intensity
If quantum wells with high indium content are used to improve light emission in the blue-green range, then the color rendering is improved, but the piezoelectric fields increase making charge carrier injection more difficult
Solution Approach 1:
The patent implements local quality by varying the indium content of quantum wells based on their position within the active region. Quantum wells with lower indium content (first type) are positioned where they experience different electric field conditions, while quantum wells with higher indium content (second type) are positioned in regions where the piezoelectric field effects are managed through corresponding doping strategies. This allows the structure to achieve broad emission spectrum coverage while managing piezoelectric field effects through localized material composition optimization.
Solution Approach 2:
The patent applies parameter changes by systematically varying the indium content parameter across different quantum wells within the active region. By adjusting the indium concentration in quantum wells from the n-side to the p-side, the patent optimizes both the optical emission properties and the electrical injection properties. This parameter variation allows quantum wells to emit across different wavelength ranges (UV, blue, green) while the corresponding doping profiles are adjusted to manage the resulting piezoelectric fields and potential barriers.
3Adaptability or versatility
If the indium content in quantum wells is increased to broaden emission spectrum, then the color rendering is improved, but the heterojunction potential barriers increase hindering charge carrier injection
Solution Approach 1:
The patent applies local quality by creating a spatial gradient of indium content across the quantum wells in the active region. Quantum wells with lower indium content are positioned adjacent to the n-doped region to facilitate electron injection, while quantum wells with higher indium content are positioned adjacent to the p-doped region where the doping profile is optimized to manage hole injection. This localized differentiation allows the structure to achieve broad emission spectrum coverage across UV, blue, and green ranges while managing the potential barriers at each heterojunction through position-specific material composition optimization.
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 configuration improves the efficiency and color rendering of light-emitting devices by facilitating better hole injection and reducing potential barriers, resulting in enhanced radiation efficiency and a more pleasant, broadened emission spectrum.
Implementation Method 1
A light-emitting structure is designed with a p-doped region and an n-doped region, featuring InGaN quantum wells of two types: low indium content quantum wells for reduced piezoelectric fields and high indium content quantum wells adjacent to the p-doped region, with controlled doping and barrier layers to enhance charge carrier injection and emission efficiency.
Implementation Method 2
At least one InGaN quantum well of a first type is arranged between the regions mentioned. A plurality of quantum wells of the first type are preferably arranged between the regions. The quantum wells of the first type are separated from one another by (In)GaN barrier layers of a first type, that is to say barrier layers of a first type, which can contain at least GaN and possibly also indium.
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The invention relates to a light-emitting structure (7) which comprises a p-doped region (1) for injecting wholes, an n-doped region (2) for injecting electrons, at least one InGaN quantum well (4) of a first type and at least one InGaN quantum well (5) of a second type, which are arranged between the n-doped region (2) and the p-doped region (1), the InGaN quantum well (5) of the second type having a higher indium content than the InGaN quantum well (4) of the first type.