Template-directed synthesis, characterization and electrical properties of Au-TiO_2-Au heterojunction nano wires

摘要

The feasibility of synthesizing metal-oxide-metal (MOM) heterojunction nanowires in the Au-TiO_2-Au system is demonstrated. The synthesis method presented here entails sequential electroplating of Au and electro-deposition of amorphous titanium oxide (TiO_x) inside nanoholes of anodic aluminium oxide (AAO) templates. This is followed by dissolving the template, and heat-treating the released nanowires, which results in the crystallization of the amorphous TiO_x segment into nanocrystalline TiO_2. Detailed transmission electron microscopy (TEM) investigation has revealed that the nanocrystalline TiO_2 is orthorhombic (columbite) phase primarily. This synthesis method has the potential to provide better control over the characteristics and architectures of the resulting MOM nanowires. The Au-TiO_2-Au nanowires were incorporated into single-nanowire devices, fabricated using a direct-write method. Nonlinear current-voltage (I-V) responses were obtained for individual MOM nanowires. The heterojunctions in such MOM nanowires are likely to offer certain advantages over all-oxide nanowires, making the MOM nanowires potentially useful as one-dimensional building blocks in the multifunctional nanoe'lectronics of the future.