Core-shell structure and unique faceting of Sn-catalyzed silicon nanowires

The potential of tin (Sn) as a catalyst for the vapor-liquid-solid (VLS) growth of silicon nanowires (SiNWs) has been relatively unexplored. Compared to the more commonly used catalysts (e.g., gold), Sn features a low eutectic point (at 235°C) and a very low equilibrium Si solubility. These features make it possible to tune the supersaturation in the catalyst and the growth kinetics at the SiNW/catalyst interface. Here, we investigate the peculiarities of Sn-catalyzed VLS growth and show that the local growth kinetics, modified by the high supersaturation in the Sn catalyst, can lead to the formation of core-shell structures and sidewall faceting of the SiNWs. Challenges facing Sn-catalyzed growth of SiNWs in VLS mode are also discussed. We suggest that the unique features of Sn catalyst will help tailor SiNW structures to meet specific application needs.