Thin SnO_2 Nanowires with Uniform Diameter as Excellent Field Emitters: A Stability of More Than 2400 Minutes

摘要

The stability of a field-emission event, i.e., the stability of the emission current over a long period of time, against thermal effects, etc., is one of the key factors for its application in real devices. Although nanostructures have the advantages of high aspect ratios and faster device turn-on times, the small masses and large surface areas make them vulnerable to both chemical and physical damages and they have a lower melting point compared to bulk materials of same compositions. SnO_2, one of the most attractive oxide semiconductors, which has with a relatively low work function of 4.7 eV, has beena perspective candidate for field emitters. A highly stable field emitter based on thin and quasi-aligned SnO_2 nanowire ensembles with uniform diameter is shown. Field-emission measurements of these SnO_2 nanowire ensembles show low turn-on and threshold voltages of 3.5 V μm~(-1) and 4.63 V μm~(-1),respectively, at an anode-sample distance of 200 urn and very long term scale stability of more than 2400 min, acquired at the electric field of 4.65 V μm~(-1).Such values are not only better than those of the recently developed SnO_2 nanostructures with different morphologies and of randomly oriented SnO_2 nanowire ensembles with a similar diameter distribution, but also compa rable with the most widely studied field-emission materials, such as carbon nanotubes and ZnO nanostructures. The potential for using these thin SnO_2 nanowire ensembles with uniform diameter in field emitters is shown, with particular promise in those operated for long-term real device applications.