GOALI: ADVANCED STUDY OF MENISCUS-CONTROLLED MATERIALS PROCESSING

Suny At Stony Brook, Stony Brook NY

Investigators

Abstract

Advanced meshless modeling and experimental study of meniscus-controlled materials processing Project summary Photovoltaic/solar energy industry has achieved growth rates in excess of 20 % over the past several years and future growth is expected to continue at 25-30% or more annually due to worldwide energy shortage. Currently, about 85% of the current production involves crystalline silicon technology. The most critical barrier to the increased use of photovoltaic generated electricity is the high cost of silicon wafers and the limitation to cost-effective silicon feedstock used to manufacture the photovoltaic cells. The edge-defined film-fed growth (EFG) technique used at Schott Solar is an efficient meniscus-controlled growth process for producing silicon wafers that are made into solar cells without "kerf loss". To further reduce costs and improve yield, it is important to find the optimal design/conditions for the growth of thin tubes/ribbons with low stress and low silicon carbide (SiC) particle incorporation. The main research goals of this GOALI proposal are to quantitatively understand meniscus dynamics and its interaction with solidification under various configurations and to develop new understanding of foreigner particle formation and incorporation in meniscus-solidification processing. To achieve the goals, the research tasks include the development of an advanced particle based model to enable an efficient modeling of multiscale transport phenomena. The model will be used to study meniscus dynamics, particle formation, precipitation, and incorporation. The resultant process model will be used to simulate the laboratory and industrial experiments for process optimization. The laboratory experiments will also be designed and performed to examine the dynamics of meniscus and tube thickness under various mechanical/thermal perturbations and to study the effects of pull rate and die-top temperature on particle incorporation during solidification. The experimental data will also be used to establish the relationships between particle incorporation and pull rate/die-top temperature. Collaborated with Schott Solar, the full-scale experiments have been and will continue to be conducted to provide the experimental data for model validation. In the help of process modeling and laboratory experiments, industrial growth system can be redesigned and operating conditions can be reexamined. Intellectual merit. The proposed research will significantly advance the fundamental understanding of meniscus stability and dynamics, particle precipitation and growth, multiphase flow, and particle incorporation in solidification processing. The proposed two-phase particle-based model is an innovative tool for solving many different kinds of free surface flow and meniscus-controlled solidification problems, such as soldering, welding, inkjet painting, droplet coating, and composite materials manufacturing. This model can also be applied to complex multiscale transport phenomena. Broader impact. Training engineering students in the area of process modeling, materials processing and manufacturing is critical for US industry. This project provides an opportunity for university and industry to work together and complement each other's expertise. It is anticipated that the enhanced understanding through the proposed research will help process design and optimization, significantly reducing cost of silicon wafers for solar application, which is urgently needed as a renewable energy source to alleviate energy shortage. The success of this proposal will potentially increase market share of photovoltaic industry in the world energy sector.