Thermal chemical vapor deposition of tin oxide nanowires in a hydrogen reduction atmosphere

Abstract

We fabricated tin oxide nanowires (NWs) on Au/Si3N4/Si(001) substrates using thermal chemical vapor deposition (CVD) in a hydrogen reduction atmosphere. Unlike typical thermal CVD conditions, a mixture of H2 and Ar gas was used as the carrier gas, and a catalyst powder such as graphite was not used. The hydrogen gas maintained the reducing atmosphere and easily vaporized the SnO2 powder without a catalyst, to supply vapors of Sn and O. This process enables vapor-liquid-solid (VLS) growth of SnO2 NWs at temperatures below 600 °C. The formation of a eutectic AuSn alloy that acts as a liquid seed during the VLS process contributes to lowering the growth temperature. X-ray diffraction and transmission electron microscopy analysis show that SnO2 NWs and SnO NWs coexist in the as-prepared sample. The oxygen-deficient atmosphere results in nucleation and growth of SnO NWs.