Oxygen annealing effect on field-emission characteristics of hydrothermally synthesized Al-doped ZnO nanowires

Al-doped ZnO (AZO) nanowires (NWs) were synthesized using low-temperature hydrothermal growth to investigate field emission (FE) characteristics. The intensity ratio of NBE peak to DLE peak (R = INBE/IDLE) increases and the half-maximum of NBE peaks (FWHMNBE) decreases with the Al contents. Experimental results reveal the FE characteristics of AZO NWs are functions of Al content. Moreover, the larger R value and the smaller FWHMNBE are found as the oxygen annealing temperature increases. The hydrothermal AZO NWs annealed in oxygen ambience with an appropriate temperature (i.e. 300–500 °C) can demonstrate the further improved FE properties (i.e. the turn-on field of 1.70 V/μm (at 1 μA/cm2), threshold field of 2.92 V/μm (at 1 mA/cm2), and β of 4547).