AVS 60th International Symposium and Exhibition
    Surface Science Monday Sessions
       Session SS+AS+NS-MoM

Paper SS+AS+NS-MoM2
Surface Hydrogen Stabilized Semiconductor Nanowire Growth

Monday, October 28, 2013, 8:40 am, Room 201 A

Session: Nanostructures: Growth & Characterization
Presenter: S. Sivaram, Georgia Institute of Technology
Authors: S. Sivaram, Georgia Institute of Technology
N. Shin, Georgia Institute of Technology
L.-W. Chou, Georgia Institute of Technology
M.A. Filler, Georgia Institute of Technology
Correspondent: Click to Email
Semiconductor nanowires exhibit tunable optoelectronic properties that are attractive for applications in energy conversion, electronics, and photonics. A fundamental knowledge of the chemical bonding that governs nanowire synthesis is essential for the a priori manufacture of nanowires with enhanced complexity and functionality. To that end, we studied the role of sidewall hydrogen during germanium nanowire synthesis with real-time in situ infrared spectroscopy. We show that covalently bonded hydrogen atoms are essential for stable <111> oriented growth and strongly influence sidewall morphology. Nanowire arrays with fixed diameter distributions and areal densities were synthesized via the vapor-liquid-solid (VLS) technique at a range of process conditions (210 − 280 °C, 5.0 × 10-5 − 1.5 × 10-4 Torr). Our spectra exhibit two intense absorption bands, at 1980 cm-1 and 1965 cm-1, whose intensities are a function of substrate temperature, precursor pressure, and nanowire elongation time. Planar adsorption studies suggest that these bands result from hydrogen bonded at Ge(100)-like and Ge(111)-like surface sites, respectively. We also demonstrate that the in situ delivery of atomic hydrogen modifies the nanowire sidewall taper, which unambiguously confirms the importance of surface chemistry on nanowire growth.