Paper IS-FrM10
Direct Observation of the Growth and Dissolution Process of SnO₂ Nanowires

Friday, November 11, 2016, 11:20 am, Room 101C

The vapor-liquid-solid (VLS) nanowire growth mechanism is a widely used synthesis technique known to produce high-quality, single crystalline nanowires. This method was first developed by Wagner and Ellis to grow silicon nanowires, and has evolved to utilize many different catalyst materials with facile control over nanowire length, diameter, and dopant concentrations. While this method is prevalent for the growth of inorganic nanowires, the growth kinetics of the VLS mechanism are not well understood, especially for binary and ternary crystal systems. Theoretical predictions suggest that the VLS growth mechanism is governed by steady-state kinetics, and that the crystal chemistry of the reverse process may be different from that which governs nanowire growth. The use of in situ microscopy techniques has advanced the understanding of the VLS growth process and nanowire growth kinetics. Through the use of in situ heating and atmosphere control in the transmission electron microscope (TEM), we have developed a method to study the forward and reverse growth mechanism of Au-catalyzed SnO₂ nanowires, the reverse process being dubbed solid-liquid-vapor (SLV) nanowire dissolution. By controlling the total pressure of the sample environment, the forward and reverse growth mechanisms can be directed. This method of observing the growth and dissolution of SnO₂ nanowires should provide an experimental platform to explore features relevant to the VLS growth mechanism, such as saturation concentration of a reactant within a VLS catalyst droplet and the use of VLS catalyst metals for controlled etching of semiconducting materials.