Non-Isolated VCSEL Array Structure for Lower Voltage and Heat Dissipation
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Solution Overview
Problem
Conventional VCSEL arrays have high driving voltage and require complex and expensive ion implantation for isolation, which complicates fabrication and affects heat dissipation.
Innovation Solution
VCSEL arrays with non-isolated emitters, where the top reflector regions are connected without isolation structures, allowing for improved current and heat flow, reducing series-resistance and thermal-resistance, and eliminating the need for ion implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ion implantation is used for emitter isolation in conventional VCSEL arrays, then emitter isolation is achieved, but fabrication complexity and cost increase
Solution Approach 1:
The patent removes the ion implantation process entirely from the fabrication sequence. Instead of using ion implantation to create isolation regions, the invention relies on the natural electrical isolation properties of the semiconductor heterostructure layers and oxide aperture formation to provide sufficient emitter isolation, thereby eliminating the complex and expensive ion implantation step while maintaining reliable device operation
Solution Approach 2:
The patent replaces the expensive and complex ion implantation process with simpler, more cost-effective fabrication steps such as selective oxidation and standard semiconductor processing techniques. The isolation function is achieved through readily available materials and processes rather than requiring specialized ion implantation equipment and procedures
2Reliability
If ion implantation is used for emitter isolation, then emitter isolation is achieved, but heat dissipation is impaired
Solution Approach 1:
By removing the ion implantation-created isolation regions, the patent eliminates the thermal barrier that these regions create. The continuous semiconductor material and improved thermal pathways allow heat to dissipate more effectively from the active regions, while emitter isolation is maintained through alternative mechanisms such as oxide apertures and heterostructure design that do not impede heat flow as severely
3Reliability
If conventional VCSEL array structure is used, then emitter isolation is achieved, but driving voltage is high
Solution Approach 1:
The patent eliminates isolation structures that create series resistance in the current path. By removing ion implantation isolation regions and their associated contact resistance, the current flows more efficiently through the VCSEL structures, reducing the overall series resistance and thereby lowering the driving voltage required to operate the array
Solution Approach 2:
The patent integrates the isolation function into the fundamental heterostructure design rather than adding separate isolation layers. The quantum well barriers and oxide apertures provide both current confinement and electrical isolation simultaneously, eliminating the need for additional isolation structures that would increase series resistance and driving voltage
4Reliability
If ion implantation process is used, then emitter isolation is achieved, but fabrication cost increases
Solution Approach 1:
The patent removes the expensive ion implantation process step from the fabrication sequence. Emitter isolation is achieved through standard semiconductor processing techniques such as selective oxidation, epitaxial growth of heterostructure layers, and photolithography-defined patterns, which are significantly less costly than ion implantation equipment and processing
Solution Approach 2:
The invention uses readily available, low-cost materials and processes to achieve emitter isolation. Instead of requiring expensive ion implantation equipment and specialized processing, the patent employs standard semiconductor manufacturing techniques that are already widely available and cost-effective, thereby reducing fabrication costs while maintaining reliable device performance
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 solution results in lower driving voltage, enhanced heat dissipation, and simplified, less expensive fabrication by providing additional routes for current and heat flow, while maintaining efficient laser operation.
Implementation Method 1
VCSELs have a vertical cavity and emit a circular beam normal to the surface
Implementation Method 2
VCSELs have a vertical cavity and emit a circular beam normal to the surface
Implementation Method 3
a current confining oxide layer below the first reflector region
Implementation Method 4
The first reflector regions of the plurality of VCSEL structures are connected such that they are not completely isolated from each other by any isolation structure
Data Source
AI summary
A VCSEL array comprises a plurality of non-isolated VCSEL emitters. Each non-isolated VCSEL emitter comprises a first reflector region, a current confining oxide layer, an oxide aperture, an active region, and a second reflector region. The current confining oxide layer and oxide aperture are made by oxidizing a relatively high Al-content layer via separate oxidation holes. The separate oxidation holes surround the oxide aperture. The first reflector regions of the plurality of non-isolated VCSEL structures are connected such that they are not isolated from each other completely by any isolation structure, and the second reflector regions of the plurality of non-isolated VCSEL structures are connected such that they are not isolated from each other completely by any isolation structure.