Lateral P-I-N Diodes for High-Voltage CMOS Integration
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Solution Overview
Problem
Conventional photovoltaic devices face challenges in achieving high voltage outputs while maintaining low power consumption, often requiring complex analog circuits, special metallization, and additional masks, which increase costs and reduce reliability, especially when integrating solar cells in series or series-and-parallel combinations on silicon substrates.
Innovation Solution
A photovoltaic device comprising a series of lateral P-I-N light-sensitive diodes formed in parallel elongated portions of a planar semiconductor material layer on an insulating layer, with patterned conductive structures connecting the diodes in series, allowing integration into standard process flows without additional masks, and optionally incorporating bypass diodes to prevent hot spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional low-voltage photovoltaic elements and dc-dc boost converters are used to achieve high voltage outputs, then voltage levels can be increased to IC system voltage, but the system requires complicated analog circuits and faces challenges with low signal processing
Solution Approach 1:
The photovoltaic device is divided into multiple discrete p-n junction solar cells that are connected in series on a single silicon substrate. Each solar cell generates a portion of the total voltage, and by segmenting the voltage generation across multiple cells, the device achieves high voltage output without requiring complex DC-DC conversion circuits
Solution Approach 2:
The patent transitions from vertical stacking of solar cells to a lateral series connection architecture. The solar cells are arranged in series along the surface of the silicon substrate, with interconnecting conductors routing current laterally between adjacent cells. This dimensional change simplifies the overall system architecture by eliminating the need for complex power management ICs
2Power
If individual solar cells are fabricated on separate silicon substrates and connected externally in series, then high voltage can be achieved, but system cost increases and reliability decreases
Solution Approach 1:
Multiple solar cells that would traditionally be fabricated on separate silicon substrates and connected externally are merged onto a single silicon substrate. The cells are interconnected using conductors formed on the same substrate, eliminating external connections and associated reliability issues while maintaining the series configuration needed for high voltage output
Solution Approach 2:
The patent introduces interconnecting conductors as intermediaries between adjacent solar cells on the same substrate. These conductors serve as mediators that transfer current laterally between cells without requiring external wiring, thereby improving reliability by eliminating external connection points while still enabling series connection for high voltage generation
3Ease of manufacture
If special metallization with aluminum paste is used to connect adjacent solar cells in series, then series connection can be achieved, but special processing is required and output voltage is limited by base shunting
Solution Approach 1:
The interconnecting conductors serve multiple functions: they act as electrical connections between solar cells, provide current collection paths, and can be integrated with standard CMOS metallization layers. This multi-functionality eliminates the need for special aluminum paste screen-printing processes while achieving reliable series connections between cells
Solution Approach 2:
The patent changes the metallization approach from screen-printed aluminum paste to deposited metal films compatible with CMOS processing. By altering the deposition method and material parameters, the device achieves series connections without requiring special high-temperature firing processes or complex metallization patterns, thereby reducing manufacturing complexity
4Reliability
If solar cells are connected in series on a single silicon substrate, then reliability improves and system cost decreases, but achieving high voltage requires additional masks and complex fabrication processes
Solution Approach 1:
The patent employs a flexible fabrication approach where the number and arrangement of solar cells can be dynamically adjusted by modifying standard photolithography masks. The fabrication process is designed to be adaptable, allowing the same basic工艺流程 to produce devices with different numbers of series-connected cells simply by changing mask patterns, thereby maintaining ease of manufacture while achieving high voltage outputs
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 solution enables the production of low-cost, high-voltage photovoltaic arrays that can be integrated into CMOS IC devices, MEMS, and solar energy concentrators, improving light conversion efficiency and reducing system complexity and cost.
Implementation Method 1
Each light-sensitive diode generates from 0.4 to 0.7 V under illumination by the sunlight
Data Source
AI summary
A photovoltaic device includes lateral P-I-N light-sensitive diodes respectively formed in portions of a planar semiconductor material (e.g., polycrystalline or crystalline silicon) layer that is entirely disposed on an insulating material (e.g., SiO2) layer utilizing, e.g., STI or SOI techniques. Each light-sensitive diode includes parallel elongated doped regions respectively formed by P+ and N+ dopant extending entirely through the semiconductor layer material and separated by an intervening elongated intrinsic (native) region. The light-sensitive diodes are connected in series by patterned conductive (e.g., metal film) structures. Optional bypass diodes are formed next to each lateral P-I-N light-sensitive diodes. Optional trenches are defined between adjacent light-sensitive diodes. The photovoltaic devices are either utilized to form low-cost embedded low power photovoltaic arrays on CMOS IC devices, or produced on low-cost SOI substrates to provide, for example, low-cost, high voltage solar arrays for solar energy concentrators.