Field Emission Properties of Metal Oxide Nanowires

The metal oxide nanowires were produced by a resistive heating of various metals under ambient conditions at normal atmospheric pressure. The obtained nanowires of CuO, V₂O₅, ZnO, Fe₂O₃ were typically of 1–5 μm in length and 10–50 nm in diameter. Field emission properties of the oxidized metal surfaces covered by the nanowires, including current–voltage dependencies and distribution of the emission sites, were measured in a flat diode configuration with the use of a phosphor coated anode. The obtained data on field emission properties were compared with the structural characteristics of the nanowires. The highest efficiency of field emission (with 5 V/μm threshold field at 0.01 mA/cm² current density) was observed for CuO nanowires. Obtained max- imal current density (up to 100 mA/cm²for such kind of cathodes is very promising for various applications in vacuum electronics.