Template-directed synthesis, characterization and electrical properties ofAu–TiO2–Au heterojunction nanowires

Abstract

The feasibility of synthesizing metal–oxide–metal (MOM) heterojunction nanowires in theAu–TiO2–Au system is demonstrated. The synthesis method presented here entailssequential electroplating of Au and electro-deposition of amorphous titanium oxide(TiOx) inside nanoholes of anodic aluminium oxide (AAO) templates. This is followed by dissolving thetemplate, and heat-treating the released nanowires, which results in the crystallization of the amorphousTiOx segment intonanocrystalline TiO2. Detailed transmission electron microscopy (TEM) investigation has revealed that the nanocrystallineTiO2 is orthorhombic (columbite) phase primarily. This synthesis method has the potential to providebetter control over the characteristics and architectures of the resulting MOM nanowires. TheAu–TiO2–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 suchMOM nanowires are likely to offer certain advantages over all-oxide nanowires, making theMOM nanowires potentially useful as one-dimensional building blocks in themultifunctional nanoelectronics of the future.