Dresden 2006 – wissenschaftliches Programm
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SYNW: Nano Wires
SYNW 1: Symposium: Nano-Wires I
SYNW 1.3: Hauptvortrag
Mittwoch, 29. März 2006, 15:00–15:30, HSZ 04
In situ Transmission Electron Microscopy Studies of Vapor-Liquid-Solid Phase Growth of Si Nanowires — •S. Kodambaka, J. B. Hannon, J. Tersoff, M.C. Reuter, R.M. Tromp, and F.M. Ross — IBM T.J. Watson Research Center, Yorktown Heights, NY 10598
Using ultra-high vacuum transmission electron microscopy (UHV-TEM), we study the growth kinetics of Si nanowires. Wires are grown in situ on Au-covered Si(111) substrates using disilane (PSi2H6 = 10−6 Torr) at temperatures between 500 and 700oC. We observe, in real-time, the growth of <111>-oriented Si wires in the presence of molten Au-Si eutectic droplets serving as the catalysts. From the TEM images of individual Si wires, acquired at video rates, we measure time-dependent changes in lengths and diameters of the wires and volumes of the Au-Si droplets. We find that the lengths of all wires increase linearly with deposition time at a temperature-dependent constant rate that is independent of the droplet diameter. Volumes of all the droplets decrease with time during both deposition and annealing in vacuum. We attribute this behavior to loss of Au due to Ostwald ripening of droplets on top of wires and incorporation on wire surfaces. We find that presence of small amounts of O2 during growth prevents loss of Au from the droplets and favors the growth of <110>-oriented Si wires. Our results provide insights into mechanisms governing the kinetics of Si nanowire growth.