Double Layer Interleaved P-N Diode Modulator Efficiency
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Solution Overview
Problem
Previous reverse-biased silicon electro-optic modulators are limited in efficiency due to the small overlap area between the p-n junction and the guided optical mode, which restricts the interaction and modulation efficiency.
Innovation Solution
The method involves forming multiple p-type and n-type doped regions on a substrate with specific masking layers to control the depth and extent of dopant implantation, increasing the overlap area between the optical field and the p-n junction, thereby enhancing the modulator's efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional single-layer p-n junction structure is used, then the device structure is simple, but the overlap area between the p-n junction and the guided optical mode is small, resulting in low modulation efficiency
Solution Approach 1:
The patent divides the single p-n junction into multiple interleaved p-n junctions arranged in layers. This segmentation increases the total junction area that interacts with the optical mode, thereby improving modulation efficiency while maintaining a structured approach to device design
Solution Approach 2:
The patent transitions from a single-layer planar structure to a multi-layer three-dimensional interleaved structure. By stacking multiple p-n junctions at different depths and lateral positions, the optical mode overlaps with multiple junction regions simultaneously, significantly enhancing modulation efficiency without excessive complexity
2Productivity
If the p-n junction area is increased to improve overlap with optical mode, then modulation efficiency improves, but the fabrication process becomes more complex
Solution Approach 1:
The patent employs preliminary masking layer formation and precise dopant implantation planning before actual junction creation. By pre-defining the interleaved pattern through masking layers, the complex multi-layer structure can be fabricated systematically, reducing manufacturing difficulty despite the increased junction area
Solution Approach 2:
The patent applies different doping regions (p-type and n-type) in specific localized areas to create the interleaved pattern. Each region is precisely controlled to achieve the desired overlap configuration, allowing complex functionality to be built from simple local doping operations
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 increases the p-n junction area, improving the efficiency of the silicon electro-optic modulators by enhancing the interaction with the optical mode, leading to better modulation performance.
Implementation Method 1
the first masking layer is operative to impinge the p-type dopants that pass through the first masking layer such that the first p-type region extends from the planar surface of the n-type doped material layer to a first depth in the n-type doped material layer
Implementation Method 2
implanting p-type dopants in the n-type doped material layer to form a first p-type doped region and a second p-type doped region
Data Source
AI summary
A method for fabricating an optical modulator includes forming n-type layer, a first oxide portion on a portion of the n-type layer, and a second oxide portion on a second portion of the n-type layer, patterning a first masking layer over the first oxide portion, portions of a planar surface of the n-type layer, and portions of the second oxide portion, implanting p-type dopants in the n-type layer to form a first p-type region and a second p-type region, removing the first masking layer, patterning a second masking layer over the first oxide portion, a portion of the first p-type region, and a portion of the n-type layer, and implanting p-type dopants in exposed portions of the n-type layer, exposed portions of the first p-type region, and regions of the n-type layer and the second p-type region disposed between the substrate and the second oxide portion.