Anomalous temperature dependence of field emission from W18O49 nanowires caused by surface states and field penetration

In this paper, we studied how field emission from thermally evaporated W18O49 nanowires depended on temperature. As the temperature changed from 300 K to 723 K, we found anomalous changes in emission current. Below an applied field of ∼12.5 V μm−1, the emission current tended to increase with rising temperature, while above 12.5 V μm−1 the current depended less on temperature in the range of 573–723 K. Furthermore, at high temperatures, we found the Fowler-Nordheim plots of these nanowires to be nonlinear. We believe that the anomalous behavior is associated with surface states at low fields and field penetration at high fields.