Semiconductor Laser Window Region Vacancy Diffusion Control
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Solution Overview
Problem
Thermal processing during the formation of a window region in semiconductor laser elements can lead to a drop in optical output due to diffusion of vacancies into the active layer, affecting current injection and laser performance.
Innovation Solution
A semiconductor laser element design featuring a layered structure with a non-window region and a window region, where the current confinement layer protrudes no less than 1.5 micrometers into the non-window region, and the width condition W2-W1 is set to be 3 micrometers or smaller, to prevent vacancy diffusion and maintain high optical output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal processing is performed to form a window region by diffusing vacancies in the semiconductor region near the facet, then the energy band gap is widened and the facet becomes transparent, but vacancies diffuse into the active layer causing optical output to drop below expected values
Solution Approach 1:
The patent divides the semiconductor laser structure into distinct regions: a window region with widened band gap for light transparency, a non-window region for light transmission, and an active layer for light generation. By spatially segmenting these functional regions and controlling vacancy diffusion boundaries, the patent prevents vacancy intrusion into the active layer while maintaining facet transparency, thus resolving the contradiction between preventing COD and maintaining optical output
Solution Approach 2:
The patent applies local quality changes by creating a window region with specifically widened energy band gap through controlled vacancy diffusion only in designated areas. The band gap energy is made larger in the window region compared to the non-window region, making the facet transparent locally without affecting the active layer's optical properties, thereby preventing COD while preserving optical output
2Productivity
If the current confinement width is decreased to increase current density for efficient current injection, then current injection efficiency is improved, but the structure becomes more complex and manufacturing precision requirements increase
Solution Approach 1:
The patent forms the current confinement structure with precise width control during the epitaxial growth process before subsequent manufacturing steps. By establishing the current confinement layer geometry in advance with predetermined width, the patent ensures accurate current path definition and high current injection efficiency while reducing the need for additional precision-critical processing steps
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 design enhances optical output by restricting vacancy diffusion, ensuring efficient current injection and preventing catastrophic optical damage, thereby achieving higher optical output and reliability.
Implementation Method 1
heat may be generated near the facet due to light absorption
Implementation Method 2
disordering a semiconductor region near the facet by diffusing impurities or vacancies in the semiconductor region
Implementation Method 3
the hole carriers injected from the upper portion of the p-type semiconductor layer flow only through the opening region of the current confinement layer
Data Source
AI summary
A semiconductor laser element includes a substrate of a first conduction type and a layered semiconductor structure formed on the substrate. The layered semiconductor structure includes a first semiconductor layer of the first conduction type formed on the substrate, an active layer formed on the first semiconductor layer, and a second semiconductor layer of a second conduction type formed on the active layer, the second conduction type being opposite to the first conduction type. The first semiconductor layer, the active layer, and the second semiconductor layer include a non-window region through which a light emitted from the active layer passes and a window region surrounding the non-window region. Band gap energy of the active layer is larger in the window region than in the non-window region. The second semiconductor layer includes a current confinement layer.