VCSEL Aperture Structure Using Oxidation Holes and Segmented Trenches
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Solution Overview
Problem
Existing vertical-cavity surface-emitting lasers (VCSELs) face issues with reliability due to electrical disconnection and performance reduction from trench formation, oxidation defects, and increased manufacturing complexity, particularly in forming multiple emitter arrays.
Innovation Solution
A VCSEL design featuring a ring-shaped trench with oxidation holes to precisely form an oxidation layer, reducing the risk of defects and electrical disconnection by isolating the window layer, and using symmetrical ohmic contact layers with protrusions to enhance connection area and reduce emitter size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the post diameter is increased to provide sufficient oxidation area, then the oxidation process becomes more difficult and time-consuming, but if the post diameter is reduced to shorten oxidation time, then the contact layer size and connection area are reduced, adversely affecting reliability
Solution Approach 1:
The patent divides the continuous ring-shaped trench into multiple discrete segments separated by gaps. This segmentation allows the oxidation layer to be formed in isolated regions rather than requiring complete circumferential oxidation, significantly reducing the oxidation time while maintaining sufficient oxidation area for reliable current confinement and contact layer formation.
2Manufacturing precision
If a ring-shaped trench is formed to concentrate current in a small aperture region, then current concentration is achieved, but the trench formation increases manufacturing complexity and creates risk of electrical disconnection
Solution Approach 1:
The continuous ring-shaped trench is segmented into discrete sections with gaps between them. This segmentation simplifies the manufacturing process by reducing the etching complexity and minimizing the risk of electrical disconnection, while still achieving effective current concentration in the aperture region through the distributed trench structure.
Solution Approach 2:
The trenches are strategically positioned to create local current confinement zones without requiring complete circumferential isolation. The gaps in the trench structure allow for localized current concentration while reducing overall manufacturing complexity and eliminating the need for continuous trench formation.
3Manufacturing precision
If a large area trench is formed around the emitter to isolate the oxidation region, then current confinement is improved, but the emitter's reliability is adversely affected from surface defects
Solution Approach 1:
The large area trench is segmented into discrete sections with gaps, creating a distributed isolation structure rather than a continuous barrier. This segmentation maintains effective current confinement in the oxidation region while reducing the total trench area that could introduce surface defects, thereby improving 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
The design enhances VCSEL reliability by preventing defects and disconnections, improving manufacturing yield, and reducing the complexity of forming multiple emitter arrays.
Implementation Method 1
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
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AI summary
The vertical-cavity surface-emitting laser (VCSEL) according to one embodiment of the present disclosure comprises: a lower mirror; an upper mirror; an active layer interposed between the lower mirror and the upper mirror; an aperture-forming layer which is interposed between the upper mirror and the active layer and has an oxidation layer and a window layer surrounded by the oxidation layer; a ring-shaped trench which penetrates through the upper mirror, the aperture-forming layer, and the active layer and defines an isolated area therein; and a plurality of oxidation holes which are provided in the isolated area surrounded by the trench and penetrate through the upper mirror and the aperture-forming layer.