1D nanomaterials: Plasma-stimulated synthesis elucidates nanowire nucleation and growth mechanisms S. Tom Picraux, DMR0413523 Arizona State University SiH 4 Au seed Si substrate Plasma stimulated Thermal growth 350ºC 0.5 nm Au Scale bars: 500 nm SiH 4 SiH 2 SiH 3 Plasma Thermal 430 470 510 400 350 1000 / T (1/K) Growth Rate (nm/min) plasma C thermal 0.74 eV 0.26 eV Vapor-liquid-solid Si nanowire growth • One objective of this research is to understand the mechanisms of nanowire (NW) growth during metal catalytically seeded vapor-liquid-solid (VLS) synthesis. • We have used plasma excitation to gain new insight into the nucleation and growth process. Strong enhancement and orientation independent growth due to plasma formed SiH 3 and SiH 2 species (Fig.1) show the vapor-liquid incorporation step and not the liquid-solid crystallization step is rate-limited mechanism. • Plasma excitation enables efficient low temperature nucleation required for NW growth (Fig.2) due to higher chemical potential. • A two-step process is demonstrated to enable lower temperature Si NW synthesis for creating nanowire heterostructures Fig. 2 SEM of low temperature Si NWs showing little nucleation of seeds by thermal and extensive growth by plasma Fig. 1 NW growth rate vs. reciprocal temperature without (thermal) and with plasma excitation for [110] & [111] NWs