Sequential physical vapor deposition and chemical vapor deposition for the growth of In2O3-SnO2 radial and longitudinal heterojunctions

Abstract Heterostructures of In 2 O 3 and SnO 2 were produced by sequential application of the physical- and chemical-vapor deposition techniques usually adopted for nanowire fabrication. In 2 O 3 nanowires exhibit a single crystal body-centered cubic structure oriented along the [1 0 0] direction and grow epitaxially on α-sapphire substrate by means of a transport and condensation method assisted by Au nanoparticles. Nucleation and growth occurred via direct vapor solid (VS) mechanism competing with catalyst-mediated vapor–liquid–solid (VLS). SnO 2 nanowires were obtained in a single crystal tetragonal (cassiterite) structure and oriented along the [1 0 1] direction, the growth being promoted by the gold particle at the apex of the In 2 O 3 nanowires. The size of the catalyst thereby determines the main morphological features of SnO 2 wires. CVD deposition allows precise control of the geometrical features of the heterojunction, also limiting detrimental nucleation of SnO 2 on the lateral sides of In 2 O 3 nanowires due to lower longitudinal growth rate. These results can help in improving the ability of finely tuning the morphological and structural properties of heterostructured oxide nanocrystals.