Low-temperature gas sensing in individual metal-oxide-metal heterojunction nanowires

CO-gas-sensing response of individual metal-oxide-metal (MOM) heterojunction nanowires (similar to 250 nm diameter) in the Au-NiO-Au system, where a nanoscale segment of NiO oxide (similar to 250 nm long) is sandwiched axially between Au nanowires, and between individual all-oxide NiO nanowires (similar to 250 nm diameter, similar to 5 mu m long), has been measured at 150 degrees C. While the all-oxide nanowires are highly resistive and show no measurable response, the MOM nanowires show similar to 25% decrease in current with the introduction of 800 ppm CO. The response is reversible, but it is slow due to the low temperature used. MOM nanowires, by virtue of the nanoscale-dimension, low-resistance oxide segment and the high-quality "end-on" metal-oxide contact, are an attractive class of nanowire gas-sensing elements for potential use in multifunctional "bottom up" nanoelectronics.