Synthesis of Silicon Nanoparticles in Nonthermal Capacitively-Coupled Flowing Plasmas: Processes and Transport

Control of the size and material properties of silicon nanoparticles plays a critical role in optimizing applications using those nanoparticles, such as photovoltaics and biomedical devices. While synthesis of silicon nanoparticles in low temperature plasmas has many attractive features, the basic mechanisms leading to formation of nanoparticles in these plasmas are poorly understood. A two-dimensional numerical model for synthesis of silicon nanoparticles (\5 nm in diameter) in radio frequency (RF) discharges was developed and used to investigate mechanisms for particle growth for Ar/He/SiH4 gas mixtures. Algorithms for the kinetics of nanoparticle formation were self-consistently embedded into a plasma hydrodynamics simulation to account for nucleation, growth, charging, and transport of nanoparticles. We found that with RF excitation in narrow tubes at pressures of a few Torr, the electric field does not fully confine charged nanoparticles in the axial direction, which then results in a finite residence time of particles in the plasma. We found that because of the high neutral nanoparticle density, coagulation plays a significant role in & Romain Le Picard [email protected] Aram H. Markosyan [email protected] David H. Porter [email protected] Steven L. Girshick [email protected] Mark J. Kushner [email protected] 1 Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455, USA 2 Electrical Engineering and Computer Science Department, University of Michigan, 1301 Beal Ave., Ann Arbor, MI 48109-2122, USA 3 Minnesota Supercomputing Institute, University of Minnesota, 117 Pleasant St. SE, Minneapolis, MN 55455, USA 123 Plasma Chem Plasma Process (2016) 36:941–972 DOI 10.1007/s11090-016-9721-6