Excimer Laser SiC Growth on Silicon Substrates
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Solution Overview
Problem
Current silicon heterojunction solar cell manufacturing processes are costly due to the need for vacuum deposition, polished silicon substrates, and corrosive chemical use, which limits efficiency and scalability.
Innovation Solution
A method using an excimer laser to form silicon carbide (SiC) layers on silicon substrates at atmospheric pressure, eliminating the need for vacuum processing and polished substrates, and enabling texturing and interconnect formation, thereby reducing costs and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If vacuum deposition and polished silicon substrates are used in silicon heterojunction solar cell manufacturing, then high quality SiC layers can be formed, but manufacturing cost increases and processing complexity increases
Solution Approach 1:
The patent replaces the mechanical vacuum deposition system with a chemical vapor deposition system operating at atmospheric pressure. The CVD process uses gaseous precursors (silane and methane) that react chemically to form SiC layers, eliminating the need for expensive vacuum equipment while achieving comparable or superior layer quality through controlled chemical reactions.
Solution Approach 2:
The patent changes the operating pressure parameter from vacuum (low pressure) to atmospheric pressure. This fundamental parameter change enables the use of standard atmospheric CVD equipment instead of expensive vacuum deposition systems, significantly reducing manufacturing cost while maintaining precise control over SiC layer formation through gas flow and temperature control.
2Manufacturing precision
If vacuum deposition processes are used, then SiC layers can be deposited, but device complexity and processing steps increase
Solution Approach 1:
The patent combines multiple functions into the atmospheric pressure CVD process: SiC layer deposition, surface texturing, and interconnect formation are all achieved in a single integrated process step. The gaseous precursors simultaneously deposit SiC and create the desired surface morphology, eliminating the need for separate vacuum deposition, texturing, and interconnect fabrication steps.
Solution Approach 2:
The atmospheric pressure CVD system serves multiple purposes: it deposits high-quality SiC layers, creates surface texturing for light trapping, and forms conductive interconnects. This multi-functional approach replaces several specialized vacuum-based processes with a single versatile atmospheric process, reducing overall device complexity.
3Manufacturing precision
If polished silicon substrates are used, then high quality heterojunctions can be formed, but material cost and processing complexity increase
Solution Approach 1:
The atmospheric pressure CVD process performs preliminary surface preparation and modification during the deposition process itself. The gaseous precursors react with the substrate surface to form the SiC layer while simultaneously creating the desired surface morphology and chemical composition, eliminating the need for preliminary mechanical polishing steps.
4Productivity
If conventional solar cell manufacturing processes are used, then solar cells can be produced, but conversion efficiency is limited and production cost is high
Solution Approach 1:
The patent creates a composite heterojunction structure combining silicon substrate with atmospheric pressure CVD-deposited SiC layers. This composite material system leverages the complementary properties of silicon (good light absorption) and SiC (wide bandgap, high thermal stability, excellent surface passivation) to achieve superior optical conversion efficiency while the atmospheric pressure process keeps manufacturing costs low.
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 allows for the fabrication of high-quality SiC/Si heterojunction devices with improved efficiency, reduced material costs, and simplified processing, enabling the use of unpolished substrates and 3D structures, while maintaining high breakdown voltages and optical conversion efficiency.
Implementation Method 1
illuminating the carbon source and silicon with an excimer laser that generates from about 200 mJ to about 1000 mJ of energy with pulses of from about 20 ns to about 1000 ns
Implementation Method 2
melting the substrate and decomposing the composition simultaneously
Implementation Method 3
decomposing the composition simultaneously
Implementation Method 4
illuminating the carbon source and silicon with an excimer laser that generates from about 200 mJ to about 1000 mJ of energy with pulses of from about 20 ns to about 1000 ns
Data Source
AI summary
A heterojunction device is provided. The heterojunction device includes a silicon (Si) substrate; and a film of silicon carbide (SiC) deposited on a surface of the Si substrate. The SiC has a Si:C ratio that increases or decreases from a SiC surface in contact with the Si substrate to an opposing SiC surface that is not in contact with the Si substrate.