Field emission properties of crystalline-SnO2 (core)/amorphous-SnO2 (shell) nanowire arrays on carbon paper

The amorphous-SnO2 (a-SnO2) thin films with different thickness were deposited on well-aligned single crystal SnO2 (c-SnO2) nanowire arrays by magnetron sputtering technology. The effects of the a-SnO2 on the morphology and field-emission (FE) properties of the c-SnO2 were investigated. The results show that the turn-on field of the nanowire increases with increasing a-SnO2 coating thickness. The c-SnO2 emitters with a-SnO2 sputtering at 10 s showed a lowest turn-on field of 0.95 V μm−1 at a current density of 10 μA cm−2 and a highest emission current density of 2.44 mA cm−2 under the field of only 1.56 V μm−1. The enhanced FE property is due to the thin a-SnO2 film in situ formed nanoparticles on the nanowire backbone, which could perform the role of tip in the surface of the nanowires and bring a significantly increased density of the electron emission sites.