Enhancement of field emission current of iron oxide nanoemitters by in-situ thermal treatment

Enhancement field emission current from iron oxide nanoemitters was observed after applying a in-situ thermal treatment process in vacuum. In one thermal treatment cycle, iron oxide nanoemitters were heated to 200 °C and kept for 2 hr. Comparison of I-V characteristics before and after thermal treatment shows that the field emission current were much enhanced from 60 μA/cm² to 500 μA/cm² at electric field of 10 MV/m. The threshold electric field decreased from 20 MV/m to 12.2 MV/m. Moreover, the enhancement was retained and the field emission current does not decrease to original level after cooling down. The emission current under different gas atmosphere were studied. The results show the observed enhancement was caused by the surface gas desorption, most likely the oxygen.