VCSEL Array Layout With Oxidation Holes for Reliable Current Confinement
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Solution Overview
Problem
Conventional vertical-cavity surface-emitting lasers (VCSELs) face manufacturing complexity and reliability issues due to wide-area etching for trench formation, leading to increased risk of electrical disconnection and surface defects that degrade emitter performance.
Innovation Solution
The VCSEL design incorporates an insulation region with implanted ions, oxidation holes, and a surface protection layer to isolate current flow and prevent defects, featuring a circular or quadrangular oxidation hole structure with smaller widths than protrusions, and a mesh-shaped connector for improved electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a ring-shaped trench is formed by etching mirror layers and active layer to concentrate current, then current concentration in a small aperture region is improved, but manufacturing complexity increases due to wide-area etching
Solution Approach 1:
The invention divides the current confinement structure into multiple segments: a circular oxidation layer surrounding the aperture, and multiple oxidation holes arranged radially outward from the aperture. This segmentation replaces the need for a continuous ring-shaped trench, simplifying the manufacturing process while maintaining effective current concentration in the aperture region.
Solution Approach 2:
The invention applies oxidation locally at specific positions (circular oxidation layer at the aperture edge and radial oxidation holes outward) rather than creating a continuous trench structure. This local oxidation approach concentrates current effectively while reducing the overall etched area and manufacturing complexity.
2Manufacturing precision
If a ring-shaped trench is formed to concentrate current, then current concentration is improved, but electrical disconnection risk increases due to pad electrode connection passing through the trench
Solution Approach 1:
The continuous trench is replaced by segmented oxidation structures (circular oxidation layer and radial oxidation holes) that do not form a complete barrier. This segmentation allows pad electrode connections to pass through the isolation region without risking disconnection, while still achieving current concentration in the aperture.
Solution Approach 2:
An isolation region is introduced as an intermediary structure between the aperture and the pad electrode connection path. This isolation region, formed by radial oxidation holes, provides electrical isolation where needed while maintaining connection pathways for the pad electrodes, thus preventing electrical disconnection issues.
3Manufacturing precision
If a large-area trench is formed around the emitter, then current concentration is improved, but emitter reliability deteriorates due to surface defects
Solution Approach 1:
Oxidation is applied locally at the aperture edge (circular oxidation layer) and at specific radial positions (oxidation holes) rather than creating a large-area continuous trench. This localized approach concentrates current effectively while minimizing the total area affected by oxidation-related surface defects, thereby improving emitter reliability.
Solution Approach 2:
The invention extracts only the essential oxidation regions needed for current concentration (circular layer at aperture edge and radial holes) rather than forming a complete large-area trench. This extraction approach maintains current concentration effectiveness while removing unnecessary oxidation that would introduce surface defects and reduce emitter reliability.
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 the reliability of VCSELs by preventing electrical disconnection and surface defects, ensuring stable emitter performance and manufacturing efficiency.
Implementation Method 1
an insulation region with implanted ions
Implementation Method 2
an aperture forming layer interposed between the upper mirror and the active layer, and including an oxidation layer and a window layer surrounded by the oxidation layer
Data Source
AI summary
A vertical-cavity surface-emitting laser (VCSEL) including a substrate including a plurality of emitters forming an array region, a lower mirror, an upper mirror, an active layer interposed between the lower mirror and the upper mirror, an aperture forming layer interposed between the upper mirror and the active layer and including an oxidation region and a window region, a connector disposed on the upper mirror, a plurality of oxidation holes passing through the upper mirror and the aperture forming layer, an upper insulation layer covering the plurality of oxidation holes, and a pad electrically connected to the connector, in which at least a portion of the connector is disposed in the plurality of oxidation holes, and the plurality of emitters is disposed in substantially a honeycomb shape on the substrate.