UV Nitride Emitter Active Layer for Better Hole Injection
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Solution Overview
Problem
Current nitride semiconductor light emitting elements that emit ultraviolet light have lower light emission output compared to those emitting visible light, necessitating an improvement in their design to enhance ultraviolet light emission efficiency.
Innovation Solution
A nitride semiconductor light emitting element is designed with a specific active layer structure comprising a first barrier layer with a higher Al composition ratio and a second barrier layer with a lower Al composition ratio, where the highest n-type impurity concentration peak is closer to the p-side semiconductor layer, to increase light emission efficiency by optimizing the band gap and hole trapping effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional active layer structure is used in ultraviolet light emitting elements, then the device can be manufactured with standard processes, but the light emission output remains low compared to visible light elements
Solution Approach 1:
The patent applies local quality by creating asymmetric doping profiles within the barrier layers. The first barrier layer has its highest n-type impurity concentration peak closer to the p-side semiconductor layer, while the second barrier layer has a more symmetric or different doping distribution. This localized variation in impurity concentration optimizes hole trapping and carrier injection specifically in regions where it most benefits ultraviolet light emission, thereby improving light emission efficiency and output without requiring complete structural redesign
Solution Approach 2:
The patent employs parameter changes by systematically varying the Al composition ratios between different barrier layers. The first barrier layer has a higher Al composition ratio than the second barrier layer, which modifies the band gap structure and carrier confinement properties. This parameter optimization enhances the efficiency of carrier recombination in the well layers, directly improving light emission output and resolving the contradiction between power output and emission efficiency
2Productivity
If the Al composition ratio is increased in barrier layers to improve carrier confinement, then light emission efficiency improves, but the band gap increases making hole injection more difficult
Solution Approach 1:
The patent resolves this contradiction by applying local quality through asymmetric doping profiles. The first barrier layer has its highest n-type impurity concentration peak positioned closer to the p-side semiconductor layer, creating a localized region that facilitates hole injection despite the high Al composition ratio. This localized doping strategy maintains strong carrier confinement in the well regions while providing efficient hole injection pathways, thereby simultaneously improving light emission efficiency and hole injection efficiency
Solution Approach 2:
The patent employs asymmetry by creating unequal Al composition ratios between the first and second barrier layers. The first barrier layer has a higher Al composition ratio optimized for carrier confinement, while the second barrier layer has a lower Al composition ratio that facilitates hole injection. This asymmetric structure balances the competing requirements of carrier confinement and hole injection, resolving the contradiction between light emission efficiency and hole injection efficiency
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 the ultraviolet light emission output by improving the light emission efficiency of the well layers, specifically the first well layer, leading to a high output nitride semiconductor light emitting element.
Implementation Method 1
an active layer positioned between the n-side semiconductor layer and the p-side semiconductor layer, wherein the active layer includes... a first well layer containing Al and emitting ultraviolet light... a second well layer containing Al and emitting ultraviolet light
Data Source
Figure 1
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AI summary
A nitride semiconductor light emitting element includes: an n-side semiconductor layer; a p-side semiconductor layer; and an active layer positioned between the n-side semiconductor layer and the p-side semiconductor layer. The active layer includes, successively from a n-side semiconductor layer side: a first barrier layer containing Al and an n-type impurity, a first well layer containing Al and emitting ultraviolet light, a second barrier layer containing Al, and a second well layer containing Al and emitting ultraviolet light. A highest n-type impurity concentration peak in the first barrier layer is located in a portion of the first barrier layer that is closer to the p-side semiconductor layer than to the n-side semiconductor layer. An Al composition ratio of the first barrier layer is higher than an Al composition ratio of the second barrier layer.