Study of Schottky contact between Au and NiO nanowire by conductive atomic force microscopy (C-AFM): The case of surface states

•NiO nanowires have abundant surface states.•The I–V characteristics of the NiO nanowires showed clear nonlinear and asymmetrical rectifying behavior.•The PC-AFM measurement was applied to investigate the influence of the surface states on the I–V characteristics.•The UV illumination cause a decrease of barrier height and an increase of reverse current.

In this work, NiO nanowires have been synthesized by a hydrothermal reaction of NiCl2 with Na2C2O4 in the presence of ethylene glycol at 180 °C for 12 h, then calcinated at 400 °C for 2 h. The NiO nanowires were analyzed by means of scanning electron microscope (SEM), atomic force microscope (AFM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The resulting current–voltage (I–V) characteristics of the NiO nanowires exhibited a clear rectifying behavior. This rectify behavior was attributed to the formation of a Schottky contact between Au coated atomic force microscopy (AFM) tip and NiO nanowires (nano-M/SC) which was dominated by the surface states in NiO itself. Photo-assisted conductive AFM (PC-AFM) was used to demonstrate how the I–V characteristics are influenced by the surface states. Our I–V results also showed that the nano-M/SCs had a good photoelectric switching effect at reverse bias.

Graphical abstractThe I–V characteristics of the NiO nanowires exhibited a clear rectifying behavior. PC-AFM was used to demonstrate how the I–V characteristics are influenced by the surface states.Figure optionsDownload full-size imageDownload as PowerPoint slide