VCSEL Multiphase Growth Sequence for Layer Quality
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Solution Overview
Problem
Conventional laser devices formed using single deposition processes often result in low-quality layers and structures, leading to defects that degrade performance, manufacturability, and reliability due to the unsuitability of processes for forming certain layers, such as reflectors and active regions.
Innovation Solution
A multiphase growth sequence is employed, utilizing Metal-Organic Chemical Vapor Deposition (MOCVD) for forming high-quality mirrors and Molecular Beam Epitaxy (MBE) for creating active regions, allowing for the formation of high-quality layers and structures in Vertical Cavity Surface Emitting Lasers (VCSELs).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single deposition process is used to form all layers, then the manufacturing process is simple, but the quality of layers and structures is low leading to defects
Solution Approach 1:
The patent divides the deposition process into two distinct phases: MOCVD phase for forming mirrors and spacers, and MBE phase for forming active regions and OA layers. This segmentation allows each process to be optimized for specific layer types, achieving high-quality layer formation without using a single complex process for all layers.
2Manufacturing precision
If MOCVD is used for all layers, then mirrors can be formed with high quality, but active regions will have poor quality and defects
Solution Approach 1:
The patent applies different deposition processes to different regions/layers based on their specific quality requirements. MOCVD is used for mirrors requiring high optical quality, while MBE is used for active regions requiring precise compositional control and low defect density. This local quality approach ensures each component achieves its optimal quality level.
3Reliability
If MBE is used for all layers, then active regions can be formed with high quality, but mirrors will have poor quality and defects
Solution Approach 1:
The patent recognizes that different layers have different quality requirements and assigns the appropriate process to each. MBE provides superior compositional control for active regions, while MOCVD provides superior optical quality for mirrors. This local quality strategy prevents the degradation of mirror quality that would occur if MBE were used for all layers.
4Reliability
If a multiphase growth sequence is used, then defect density is reduced and layer quality is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent segments the growth sequence into distinct MOCVD and MBE phases with clear transitions. Each phase is optimized for specific layers, reducing defects by using the appropriate process for each component. The segmented approach manages complexity through structured organization rather than attempting to optimize all layers with a single process.
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 enhances the performance, manufacturability, and reliability of VCSELs by reducing defects and improving the quality of layer formation, compared to single-process deposition methods.
Implementation Method 1
the first mirror and the first spacer are formed using an MOCVD process during a first MOCVD phase of the multiphase growth sequence
Implementation Method 2
the active region is formed using an MBE process during an MBE phase of the multiphase growth sequence
Data Source
AI summary
A method of forming a vertical cavity surface emitting laser (VCSEL) device using a multiphase growth sequence includes forming a first mirror over a substrate; forming an active region (e.g., a dilute nitride active region) over the first mirror; forming an oxidation aperture (OA) layer over the active region; forming a spacer on a surface of the OA layer; and forming a second mirror over the spacer. The active region is formed using a molecular beam epitaxy (MBE) process during an MBE phase of the multiphase growth sequence and the second mirror is formed using a metal-organic chemical vapor deposition (MOCVD) process during an MOCVD phase of the multiphase growth sequence.