AlGaN Cladding Profile for Low-Absorption Nitride Laser Emission
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Solution Overview
Problem
Current nitride semiconductor light emission elements face challenges in achieving high positive hole concentration and efficiency due to low positive hole mobility in gallium nitride, leading to deteriorated laser characteristics from increased light absorption in p-type cladding layers with high Mg doping.
Innovation Solution
A nitride semiconductor light emission element configuration where the Al composition of the AlGaN cladding layer decreases away from the substrate interface, and the Mg concentration is optimized to have a maximum value at the interface, reducing light absorption and improving laser characteristics by suppressing memory effects during the growth process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the doping amount of Mg in the cladding layer is increased to achieve high positive hole concentration, then light emission efficiency is improved, but light absorption increases and laser characteristics are deteriorated
Solution Approach 1:
The patent applies local quality by creating a non-uniform Mg concentration distribution within the cladding layer. The Mg concentration is set to decrease from the substrate interface toward the upper surface, with specific concentration ranges defined for different depth regions. This spatial variation in doping concentration allows the lower region to provide high positive hole concentration for efficient light emission, while the upper region maintains lower light absorption, thus resolving the contradiction between emission efficiency and laser characteristics.
2Reliability
If the Al composition in the AlGaN cladding layer is increased to improve light extraction efficiency, then light extraction is improved, but light absorption increases and laser characteristics are deteriorated
Solution Approach 1:
The patent applies local quality by creating a non-uniform Al composition distribution within the AlGaN cladding layer. The Al composition is set to decrease from the substrate interface toward the upper surface, with specific composition ranges defined for different depth regions. This spatial variation allows the lower region to provide high light extraction efficiency, while the upper region maintains lower light absorption, thus resolving the contradiction between light extraction efficiency and laser characteristics.
3Reliability
If high Mg doping is used to achieve high positive hole concentration, then positive hole injection efficiency is improved, but light absorption increases and laser characteristics are deteriorated
Solution Approach 1:
The patent applies local quality by creating a non-uniform Mg concentration distribution within the cladding layer. The Mg concentration is set to decrease from the substrate interface toward the upper surface, with specific concentration ranges defined for different depth regions. This spatial variation in doping concentration allows the lower region to provide high positive hole injection efficiency, while the upper region maintains lower light absorption, thus resolving the contradiction between injection efficiency and laser characteristics.
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 light emission efficiency and improves laser characteristics by controlling the Mg concentration and Al composition gradient, reducing light absorption and maintaining p-type semiconductor properties, thus overcoming the limitations of high Mg doping.
Implementation Method 1
an increase in the doping amount of Mg in a cladding layer increases light absorption, and thus there is a problem that laser characteristics are deteriorated
Data Source
AI summary
A nitride semiconductor light emission element including a substrate having a (0001) plane as a lamination plane, an n-type semiconductor layer, an active layer, a p-type semiconductor layer, and a contact layer in this order, the p-type semiconductor layer including a cladding layer including AlGaN, in which an Al composition (50) of the cladding layer (18) is formed to be smaller as being away from an interface on the substrate side, a Mg concentration (52) of the cladding layer (18) is formed to have a maximum value at the interface (52d) on the substrate side or a maximal value (52a) in a direction of being away from the interface on the substrate side, and the nitride semiconductor light emission element achieves a suppression of light absorption and thus improving laser characteristics, by decreasing the doping amount of Mg by suppressing a memory effect.