Preparation of radial and longitudinal nanosized heterostructures of In2O3 and SnO2

Radial and longitudinal nanosized In2O3-SnO2 heterostructures were produced by applying a suitable methodology of transport and condensation. Sequential evaporation-condensation over In-seeded alumina promotes the formation of a radial heterostructure, driven by the direct vapor-solid growth mechanism. The single-crystalline In2O3 nanowire nucleates and acts as the backbone for condensation of a polycrystalline SnO2 sheath. Fabrication of longitudinal heterostructures over sapphire is achieved through the application of a nanosized gold catalyst: the gold particles promote nucleation according to the vapor-liquid-solid mechanism, and lead to the formation of single-crystalline In2O3 nanowires with a gold droplet at the apex. Gold maintains its catalytic activity even during subsequent evaporation of SnO2.and induces the nucleation of a SnO2 single-crystal nanowire from the termination of an In2O3 nanowire. The electrical characterization of the longitudinally assembled In2O3-SnO2 structure highlighted a peculiar behavior, as the heterojunction of two n-type semiconducting oxides was revealed, tin oxide being reversely biased. These results hold great potential for the application of precisely shaped heterojunctions.