Correlation between field emission current limits and morphology changes of poly- and single-crystalline gold nanowire patches

Well aligned and highly efficient field emission (FE) results have been obtained with regular arrays of gold nanowire (NW) patches [1]. However, strong variations of the maximum current Imax among single Au-NW patches have been attributed to contact problems between wires and substrate [2]. Recently we have focused our research in finding a systematic correlation between FE properties and morphology changes of preselected patches caused by FE current processing. Typical SEM images of a polycrystalline Au-NW patch before and after FE scanning microscope measurements are shown in Fig. 1. The patch (as fabricated) is formed by randomly distributed NWs, most of which are solitary and vertically aligned. After processing, about 30-40% of the patch area is modified. The NWs located within the patch area where the local FE measurements were performed suffered dramatic morphological changes, while NWs at several μm distance from the bright area seem not to be affected. Therefore, these unmodified emitters are responsible for the final emission current of this patch (~ 0.7 μA at 90 V/μm).