AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Silicon Particle Formation and Growth in Silane Pyrolysis Reactors
MIGUEL VAZQUEZ PUFLEAU, Martin Yamane, Shalinee Kavadiya, Thimsen Elijah, Pratim Biswas, Washington University in St. Louis
Abstract Number: 463 Working Group: Nanoparticles and Materials Synthesis
Abstract Crystalline silicon devices comprise the majority (>70%) of the photovoltaic market. A key cost driver in the manufacture of silicon PV is the energy-intensive chemical vapor deposition (CVD) step in the refining process, which produces polysilicon in a highly pure state. Alternate fluidized-bed reactors (FBR) have been proposed for the production of the silicon. While Fluidized-bed CVD reactor operation is more economically viable than the conventional Siemens process, it is plagued by issues related to aerosol nucleation that results in ultrafine particle formation. This is an unwanted side reaction that occurs in parallel to the desired reaction for condensational/ surface reaction growth of the desired larger particles. Despite decades of research, the silane pyrolysis mechanism under industrially-relevant conditions, which is the key to understanding the formation of ultrafine particles, is still under debate. In this work, we propose to measure the formation and growth rates for silane pyrolysis using both online and offline characterization methods. Online methods include scanning mobility particle size distribution measurements, while offline methods include analysis of scanning and transmission electron micrographs for primary particle characterization within agglomerates. Material and temporal balances will be solved simultaneously to determine the growth rates. Characterization results from industrial scale FBRs will also be presented. A discrete-sectional model to describe the different mechanistic pathways will be presented.