Synthesis, Electrical Measurement, and Field Emission Properties of a-Fe2O3 Nanowires

a-Fe2O3 nanowires (NWs) were formed by the thermal oxidation of an iron film in air at 350 C for 10 h. The rhombohedral structure of the a-Fe2O3 NWs was grown vertically on the substrate with diameters of 8–25 nm and lengths of several hundred nm. It was found that the population density of the NWs per unit area (DNWs) can be varied by the film thickness. The thicker the iron film, the more NWs were grown. The growth mechanism of the NWs is suggested to be a combination effect of the thermal oxidation rate, defects on the film, and selective directional growth. The electrical resistivity of a single NW with a length of 800 nm and a diameter of 15 nm was measured to be 4.42 9 10 Xcm using conductive atomic force microscopy. The field emission characteristics of the NWs were studied using a two-parallel-plate system. A low turn–on field of 3.3 V/lm and a large current density of 10 A/cm (under an applied field of about 7 V/lm) can be obtained using optimal factors of DNWs in the cathode.