Characterization and electrical properties of individual Au-NiO-Au heterojunction nanowires

High-definition metal-oxide-metal (MOM) heterojunction nanowires in the Au-NiO-Au system have been synthesized using a template-based method. These nanowires are ∼70 nm in diameter and ∼7 μm in total length, with a 100 to 300 nm wide NiO segment sandwiched between the Au nanowires axially. Detailed electron-microscopy characterization studies of these nanowires show that the oxide segment is primarily cubic NiO and nanocrystalline, and that both the Au-NiO interfaces are well-defined. These Au-NiO-Au nanowires have been incorporated into high-quality single-nanowire devices, fabricated using a direct-write method. The current-voltage (I-V) responses of individual Au-NiO-Au nanowires have been measured as a function of temperature in the range 298 to 573 K. While the I-V response at room temperature has been found to be non-linear, it becomes more linear and less resistive with increasing temperature. These types of MOM nanowires are likely to offer certain advantages over all-oxide nanowires in fundamental size-effect studies, and they could be potentially useful as nanoscale building blocks for multifunctional nanoelectronics of the future.