(d)

1. Catalyzed Nucleation and Growth of Semiconductor NanowiresWei Cai, Stanford University, DMR 0907642 Semiconductor nanowires (NWs) synthesized by locally-catalyzed crystal growth are of great interest, largely because of their potential to enable scaling of semiconductor devices to molecular dimensions. Achieving necessary degree of control of nanowire growth for technological applications would be greatly simplified if the mechanism underlying NW nucleation, growth and growth termination were understood to the extent required for predictive modeling. Fig 1 shows the binary phase diagram of Si-Au model developed for this project, with a molecular dynamics simulation snapshot of the Si-Au alloy droplet on Si NW during growth. Fig. 2 shows that we can use light scattering as a way to monitor NW nucleation and growth in situ, and that we can also use Ni nanoparticles (instead of Au) to catalyze NW nucleation and growth. O Ba Fig 1 (a) Si-Au binary phase diagram of our potential model compared with experiment. (b) Molecular dynamics simulation snapshot of Si-Au droplet on top of Si NW. The red line indicates the shape of liquid-solid interface. (d) Si (e) Fig 2 (a) Ellipsometric diagram for Ge substrates with Au nanoparticles at various T in presence of germane. (b-c) SEM image at 330oC and 360oC. (d-e) TEM image of CVD grown Ge NW using Ni nanoparticles at 375oC.

2. Catalyzed Nucleation and Growth of Semiconductor NanowiresWei Cai, Stanford University, DMR 0907642 PI Cai hosted Alfonso Garcia, a physics and chemistry high school teacher of the Latino College Preparatory Academy, during the Stanford 2010 summer program, Industry Initiatives for Science and Math Education (IISME). Alfonso works with graduate student SeunghwaRyu, who is supported by this project, to learn how to use MD++ program to develop education modules for high school students. MD++ is the same program which Seunghwa used to perform molecular dynamics simulations the NW growth process. During this summer, Alfonso successfully implemented the Brenner potential in MD++ and performed MD simulations of carbon nanotubes in tensile loading. Analyzing the Tensile Strength of SWCNT's of the Zigzag Type and Armchair Type via MD++ Simulation Presenter: Alfonso R. Garcia PI: Professor Wei Cai, Mentors: SeunghwaRyu and Keonwook Kang, Mechanical Engineering Mechanics and Computation, Durand Hall High school teacher Alfonso Garcia presented poster at the 2010 IISME summer program at Stanford. Alfonso was hosted by PI Cai’s group.