Nitride Light-Emitting Element with Tunnel Junction Active-Layer Tuning
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Solution Overview
Problem
Existing nitride semiconductor light-emitting elements face challenges in maintaining high luminous efficiency due to degradation in crystallinity when increasing n-type impurity concentration for tunnel junctions, which affects the performance of the active layers.
Innovation Solution
The design includes a first active layer with alternating well and barrier layers of specific thicknesses, and a second active layer with thinner well and thicker barrier layers, improving crystallinity by maintaining a favorable thickness ratio to enhance luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the n-type impurity concentration is increased to form tunnel junctions, then the electrical conductivity is improved, but the crystallinity of the active layers deteriorates
Solution Approach 1:
The patent applies local quality by creating distinct structural characteristics in different regions of the active layer. The first active layer has a first well layer thickness and first barrier layer thickness, while the second active layer has a second well layer thickness and second barrier layer thickness. This local differentiation allows each region to be optimized for its specific function, enabling the tunnel junction region to achieve high electrical conductivity while preserving crystallinity in the light-emitting active layer regions.
Solution Approach 2:
The patent segments the active layer into multiple distinct layers with different thickness ratios. By dividing the structure into a first active layer and a second active layer, each with specific well and barrier layer thicknesses, the patent enables different regions to serve different functions. The segmentation allows the tunnel junction to be formed in one region without compromising the crystallinity in other regions that are critical for light emission.
2Illumination intensity
If the well layer thickness is increased, then the light emission intensity is improved, but the crystallinity degradation propagates to subsequent active layers
Solution Approach 1:
The patent implements local quality by establishing different thickness ratios in different active layers. The first active layer has a first well layer thickness and first barrier layer thickness optimized for initial light emission, while the second active layer has a second well layer thickness and second barrier layer thickness configured to maintain crystallinity. This local optimization ensures that light emission intensity is achieved in the first layer without propagating crystallinity degradation to the second layer.
Solution Approach 2:
The patent segments the active layer structure into multiple independent units with different thickness characteristics. By creating a first active layer and a second active layer with distinct well and barrier layer thicknesses, the patent prevents the propagation of crystallinity degradation. Each segmented layer can be independently optimized, allowing the first layer to emit light intensely while the second layer maintains high crystallinity for sustained performance.
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 enhances the crystallinity of the active layers, leading to increased luminous efficiency in the nitride semiconductor light-emitting elements.
Implementation Method 1
The second n-side semiconductor layer has a tunnel junction with the first p-side semiconductor layer
Implementation Method 2
a first active layer located on the first n-side semiconductor layer, a first p-side semiconductor layer located on the first active layer
Data Source
AI summary
A nitride semiconductor light-emitting element includes a first n-side semiconductor layer, a first active layer located on the first n-side semiconductor layer, a first p-side semiconductor layer located on the first active layer, a second n-side semiconductor layer located on the first p-side semiconductor layer, a second active layer located on the second n-side semiconductor layer, and a second p-side semiconductor layer located on the second active layer. The second n-side semiconductor layer has a tunnel junction with the first p-side semiconductor layer. The first active layer includes a first well layer and a first barrier layer alternately arranged in a stacking direction. The second active layer includes a second well layer and a second barrier layer alternately arranged in the stacking direction. The second well layer is thinner than the first well layer. The second barrier layer is thicker than the first barrier layer.