Nitride Semiconductor Light-Emitting Element Electron Blocking Stack
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Solution Overview
Problem
Nitride semiconductor light-emitting elements, despite optimizations in film thicknesses of barrier and well layers, often fail to achieve sufficient emission intensity, leaving room for further improvement in emission output.
Innovation Solution
A nitride semiconductor light-emitting element is designed with an active layer comprising an AlGaN-based barrier layer, a p-type contact layer, and an electron blocking stack body. The electron blocking stack body includes a first electron blocking layer with a higher Al composition ratio on the active layer side and a second electron blocking layer with a lower Al composition ratio on the p-type contact layer side, along with a p-type cladding layer to enhance emission output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the film thicknesses of the final barrier layer and well layers are optimized to 2-10 nm and not more than 2 nm respectively, then the emission intensity is improved, but sufficient emission intensity is not achieved in some cases
Solution Approach 1:
The electron blocking layer is divided into two distinct layers: a first electron blocking layer with higher Al composition ratio (0.6-0.8) and a second electron blocking layer with lower Al composition ratio (0.2-0.5). This segmentation allows each layer to perform different functions - the first layer provides strong electron blocking capability while the second layer reduces electrical resistance, collectively achieving sufficient emission intensity that cannot be achieved with a single optimized barrier layer
Solution Approach 2:
Different regions of the electron blocking structure are assigned different Al composition ratios to optimize local properties. The first electron blocking layer positioned adjacent to the active layer has higher Al content for maximum electron blocking, while the second electron blocking layer positioned toward the p-type contact layer has lower Al content for reduced resistance. This local quality differentiation resolves the contradiction by allowing simultaneous optimization of blocking performance and electrical conductivity in different locations
2Productivity
If a single barrier layer with optimized thickness is used, then the device complexity is reduced, but the emission output cannot be sufficiently enhanced
Solution Approach 1:
The electron blocking function is segmented into two layers with different compositions rather than using a single homogeneous layer. This segmentation enables the structure to achieve higher emission output by simultaneously providing strong electron blocking and low electrical resistance, while maintaining a relatively simple overall device architecture that only adds one additional layer interface
Solution Approach 2:
The electron blocking structure uses a composite approach with two layers of AlGaN having different Al composition ratios. This composite structure combines the advantages of high-Al-content materials (superior electron blocking) and low-Al-content materials (lower resistance) within a single integrated component, achieving enhanced emission output without proportionally increasing device complexity
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 significantly enhances emission output by improving electron blocking and reducing electrical resistance, leading to increased luminous efficiency and emission intensity.
Implementation Method 1
an electron blocking stack body located between the active layer and the p-type contact layer, wherein the electron blocking stack body comprises a first electron blocking layer and a second electron blocking layer, the first electron blocking layer being located on the active layer side and having a higher Al composition ratio than an Al composition ratio in the barrier layer
Implementation Method 2
the second electron blocking layer being located on the p-type contact layer side and having a lower Al composition ratio than an Al composition ratio in the barrier layer
Implementation Method 3
an active layer comprising an AlGaN-based barrier layer
Data Source
AI summary
A nitride semiconductor light-emitting element includes an active layer including an AlGaN-based barrier layer, a p-type contact layer located on an upper side of the active layer, and an electron blocking stack body located between the active layer and the p-type contact layer. The electron blocking stack body includes a first electron blocking layer and a second electron blocking layer. The first electron blocking layer is located on the active layer side and has a higher Al composition ratio than an Al composition ratio in the barrier layer. The second electron blocking layer is located on the p-type contact layer side and has a lower Al composition ratio than an Al composition ratio in the barrier layer.