Significant field emission enhancement in ultrathin nano-thorn covered NiO nano-petals†
A power efficient and stable field emission (FE) has been reported here from ultrathin nanothorn covered nickel oxide (NiO) nanopetals (NPs) fabricated using a simple hydrothermal technique. Three orders of magnitude improved electron FE, in terms of threshold and turn-on fields, has been observed from these NiO-NPs. Uniform and vertically aligned NiO-NP structures, grown on a very flat conducting surface (FTO coated glass), show sharp needle like structures on the top edges of the flakes. These ultrafine structures play the main role in FE starting at such a low turn on field. A field enhancement factor of approximately five million and threshold field of 3 V mm−1 has been estimated by analyzing the FE data (J–E plot) within the framework of Fowler–Nordheim (FN). Modification in device geometry and surface micro- (nano-) structure has been found to play the key role in addressing the bottlenecks in achieving an efficient FE.