Conducting Aperture VCSEL Structure for Low Junction Capacitance
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Solution Overview
Problem
Existing optoelectronic devices face limitations in high-speed data communication due to electric parasitic effects dominated by device resistance and capacitance, which restrict the modulation bandwidth and data transmission rate.
Innovation Solution
The formation of conducting apertures laterally confined by dielectric or void regions, electrically isolated from the active region, reduces the depletion capacitance by minimizing the p-n junction area, allowing for high conductivity and low resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the p-n junction area is reduced to lower capacitance, then the modulation bandwidth improves, but the device resistance increases
Solution Approach 1:
The patent applies local quality by creating laterally confined conducting apertures within the p-n junction structure. The aperture regions provide high conductivity paths for current flow, while the surrounding dielectric or void regions provide electrical isolation. This local differentiation allows the device to maintain low resistance through the conducting aperture paths while achieving low capacitance through the reduced effective junction area provided by the confined aperture structure.
Solution Approach 2:
The patent segments the p-n junction into distinct conducting aperture regions and insulating dielectric or void regions. This segmentation creates multiple localized conducting paths that collectively provide low resistance while the overall effective area remains small, thereby achieving both low capacitance and low resistance simultaneously rather than the traditional trade-off.
2Speed
If conducting apertures are laterally confined by dielectric regions, then capacitance is reduced, but device complexity increases
Solution Approach 1:
The patent extracts the insulating function from traditional doped semiconductor layers and implements it through dielectric regions or voids that are laterally confined around the conducting apertures. This extraction allows the conducting aperture regions to be clearly defined and isolated, reducing the effective capacitance-forming area while maintaining simple fabrication processes through selective oxidation or etching techniques.
Solution Approach 2:
The dielectric regions serve as intermediary elements that provide electrical isolation between adjacent conducting apertures. These dielectric mediators enable the device to achieve low capacitance through lateral confinement without requiring complex three-dimensional structures or multiple processing steps, as the dielectric layers can be integrated into existing VCSEL fabrication sequences.
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 enables a significant reduction in device capacitance, enabling modulation bandwidths beyond 100 GHz and improved data transmission rates by reducing parasitic effects.
Implementation Method 1
The formation of conducting apertures laterally confined by dielectric or void regions, electrically isolated from the active region
Implementation Method 2
reduces the depletion capacitance by minimizing the p-n junction area
Implementation Method 3
allowing for high conductivity and low resistance
Data Source
AI summary
A semiconductor optoelectronic device formed of a p-doped region, an undoped active region, and an n-doped region, contains at least one conducting transformation layer subject to transformation. Possible transformations include selective oxidation or selective etching or their combination resulting in a conducting aperture confined by an electrically insulating region formed of dielectric or void. The intermediate layer between the transformation layer and the active region is undoped. The conducting aperture can provide induced doping of a part of the intermediate layer close to the aperture, enabling electric conductivity towards the active region, while the other parts of the initially undoped intermediate layer remain undoped. This results in a significant reduction of the area of the p-n junction, and, thus, in a significant reduction of the device capacitance. The disclosure applies to vertical cavity surface emitting lasers (VCSELs) and to other types of light-emitting devices as well as to photodetectors.