VCSEL Array Electrical Isolation via Buffer Structure
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Solution Overview
Problem
Existing vertical-emitting device arrays formed on semi-insulating substrates face reliability issues due to higher defect rates, which affect the quality and reliability of the emitter array, and require complex trench structures for electrical isolation, increasing manufacturing complexity and cost.
Innovation Solution
The use of a doped substrate with a buffer structure and isolation structure, such as reverse p-n junctions and trench-based isolation, provides both vertical and horizontal electrical isolation between adjacent vertical-emitting devices, allowing for in-series powering and improved reliability without the need for semi-insulating substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If semi-insulating substrates are used for vertical-emitting device arrays, then electrical isolation is achieved, but defect rates increase and reliability decreases
Solution Approach 1:
The patent introduces an intermediary buffer structure between the conducting substrate and the vertical-emitting devices. This buffer structure includes a first portion and a second portion that together provide electrical isolation without requiring semi-insulating substrates. The intermediary buffer structure mediates between the conducting substrate and the emitter array, eliminating the defect issues associated with semi-insulating substrates while maintaining necessary electrical isolation.
2Reliability
If trench structures are used for electrical isolation between adjacent devices, then electrical isolation is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent extracts the electrical isolation function from the substrate itself and relocates it to a dedicated buffer structure. Instead of relying on the substrate material properties (semi-insulating) or complex trench structures, the isolation function is taken out and implemented through the buffer structure's specific layer configuration, simplifying the overall device structure while maintaining effective electrical isolation.
Solution Approach 2:
The patent changes the electrical parameter distribution through the buffer structure's layered design. By creating specific regions with different doping characteristics (first portion and second portion of the buffer structure), the patent achieves electrical isolation through parameter variation rather than structural complexity, eliminating the need for deep trenches or semi-insulating materials.
3Reliability
If buffer structures are used for electrical isolation on conducting substrates, then reliability improves and defect rates decrease, but device spacing must increase
Solution Approach 1:
The patent addresses the spacing issue by transitioning from a lateral isolation approach to a vertical isolation approach. The buffer structure provides electrical isolation in the vertical dimension between the conducting substrate and the emitter array, rather than requiring lateral separation through increased device spacing. This dimensional shift allows compact device布局 while maintaining 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 approach enhances the quality and reliability of the emitter array by reducing defect likelihood, simplifying manufacturing, and enabling closer device spacing, thus increasing device density and reducing costs.
Implementation Method 1
The buffer structure, or a combination of the buffer structure and a layer of the plurality of VCSELs, may include multiple reverse p-n junctions to provide electrical isolation from the plurality of vertical-emitting lasers to the doped substrate layer
Implementation Method 2
The isolation structure may provide electrical isolation between a first VCSEL, of the adjacent VCSELs, and a second VCSEL of the adjacent VCSELs
Data Source
AI summary
A vertical cavity surface emitting laser (VCSEL) array may comprise a doped substrate layer. The VCSEL array may comprise a plurality of VCSELs on the doped substrate layer. The VCSEL array may comprise a buffer structure between the doped substrate layer and the plurality of VCSELs. The buffer structure, or a combination of the buffer structure and a layer of the plurality of VCSELs, may provide electrical isolation from the plurality of VCSELs to the doped substrate layer. The VCSEL array may comprise an isolation structure between adjacent VCSELs of the plurality of VCSELs. The isolation structure may provide electrical isolation between a first VCSEL, of the adjacent VCSELs, and a second VCSEL of the adjacent VCSELs. The first VCSEL and the second VCSEL may be different VCSELs.