Ultra-low turn-on field from ultra-long ZnO nanowire arrays emitters

Ultra-long and well-aligned ZnO nanowire arrays have been synthesized on p-Si (8–13 Ω cm) substrates by vapor phase transport (VPT) method. The length of the nanowire arrays can be modified by adjusting the distance between the source and substrates. Their field emission properties were investigated and the lowest turn-on voltage was observed at 1.08 V/μm. The exceptional field emission performances are attributed to the intrinsically high aspect ratios of ultra-long ZnO nanowire arrays. Our results show another feasible route to enhance field emission performance of ZnO nanowire arrays.