Field emission characteristics of individual ZnO nanowire before vacuum breakdown

The field emission characteristics of individual ZnO nanowire before breakdown were investigated. A current saturation was found during the pre-breakdown process. Mechanisms including the effects of joule heating, nanowire resistance and space charge effect have been considered. The analysis using simulation shows the phenomena could be related to space charge effect. However, more experimental and theoretical work should be carried out to pinpoint the exact mechanisms.