Semiconductor Laser Window Layer Diffusion Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor lasers face challenges in minimizing leakage current at the window layer without compromising the operation rate of the crystal growing apparatus and increasing manufacturing costs, particularly due to the difficulty in growing thick AlGaAs buffer layers which can lead to exhaust gas filter clogging and reduced growing rates.
Innovation Solution
A semiconductor laser design incorporating a diffusion suppressing layer with a lower Al ratio than the buffer layer, combined with a quantum well active layer and strategically formed window layers to control impurity diffusion, allowing for reduced buffer layer thickness and enhanced crystal growth rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick AlGaAs buffer layer is formed to stop Zn diffusion and minimize leakage current, then leakage current is reduced, but the crystal growing apparatus operation rate is lowered due to exhaust gas filter clogging and reduced growing rate
Solution Approach 1:
The buffer layer is divided into multiple layers with different Al compositions: a first AlGaAs buffer layer with higher Al content (x1=0.3-0.7) for effective Zn diffusion blocking, and a second AlGaAs buffer layer with lower Al content (x2=0.1-0.3) that grows faster and causes less exhaust gas filter clogging. This segmentation allows the thick buffer layer to be formed while maintaining high operation rate
Solution Approach 2:
Different regions of the buffer layer have different Al compositions optimized for different functions: the lower Al composition region (second buffer layer) provides fast growth and low carbon intake, while the higher Al composition region (first buffer layer) provides effective Zn diffusion blocking. Each layer has local quality optimized for its specific role
2Reliability
If AlGaAs buffer layer with high Al composition is used to stop Zn diffusion, then leakage current is minimized, but carbon intake increases and growing rate must be held low
Solution Approach 1:
The buffer layer is segmented into two parts: a second AlGaAs buffer layer with low Al composition (x2=0.1-0.3) that grows fast with low carbon intake, and a first AlGaAs buffer layer with high Al composition (x1=0.3-0.7) that effectively blocks Zn diffusion. This allows achieving both high growing rate and effective diffusion blocking
Solution Approach 2:
The Al composition parameter is changed across different buffer layer regions. The second buffer layer uses low Al composition (0.1-0.3) for fast growth, while the first buffer layer uses high Al composition (0.3-0.7) for diffusion blocking. This parameter change allows optimizing both growth rate and diffusion blocking 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 approach effectively minimizes leakage current at the window layer while maintaining high operation rates for the crystal growing apparatus and reducing manufacturing costs by controlling impurity diffusion and optimizing layer thickness.
Implementation Method 1
the diffusion of Zn stops at the buffer layer to form p-n junction, and Zn is not diffused into the substrate side
Data Source
AI summary
A first buffer layer (GaAs), a second buffer layer (AlGaAs), and a diffusion suppressing layer consisting of GaAs or AlGaAs are stacked on a GaAs substrate. The structure has a first cladding layer thereon. When AlGaAs is used for the diffusion suppressing layer, the Al ratio of AlGaAs is made smaller than in the second buffer layer. In such a structure, when a window region is formed, the diffusion rate of the impurity (Zn) can be lowered in the diffusion suppressing layer, and the diffusion of the impurity can be stopped at the second buffer layer.