One-Step Growth and Field Emission Properties of SnO2-Capped Silicon Nanowires: A Sn-Catalyzed Approach

SnO2-capped Si nanowires have been reproducibly fabricated via a simple one-step chemical vapor deposition (CVD) method, in a high yield and uniform distribution. The Sn-catalyzed reaction is determined by a process of combined vapor−liquid−solid (VLS) and oxide-assisted growth (OAG) mechanism. Detailed microstructures of the nanowires have been investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), together with X-ray diffraction (XRD) analysis and Raman spectroscopy. Field emission (FE) measurements revealed that the SnO2-capped nanowire structure can significantly reduce the turn-on field value of silicon nanostructures to ∼3.7 V/μm and even lower. A dual-component model for the motion of electrons in the unique heterojunction architecture has been proposed, in comparison with the classical Fowler−Nordheim (FN) theory. Furthermore, adsorption effects have also been confirmed in the actual course of field emission, which can play an important role in the realizati...