Temperature dependent field emission performances of carbon nanotube arrays: Speculation on oxygen desorption and defect annealing

We report here a systematic study of the field emission (FE) properties of highly ordered carbon nanotube (CNT) arrays at different temperatures. The FE characteristics of the CNT arrays are significantly improved with temperature increasing from 298 K to 473 K, as evidenced by the decreases of turn-on electric field at 10 μA/cm2 from 1.064 to 0.774 V/μm and threshold field at 10 mA/cm2 from 1.628 to 1.418 V/μm, respectively. Moreover, the stability behavior of the CNT arrays is ameliorated at or after suffering to temperatures. Raman, EDS, XPS, and photoelectron spectrometer were employed to characterize the CNT arrays before and after the FE-Temperature measurements for comparison. Our results demonstrate that the oxygen desorption induced work function decrease (from 4.89 to 4.68 eV) of the CNT arrays after longtime exposure to temperature is responsible for the improved FE behavior, while the annealing of defects on CNTs is the main reason for the improved FE stability, which provides an effective approach to stabilizing emitters by temperature processing.