Negative differential resistance in ZnO nanowires induced by surface state modulation

Negative differential resistance was observed in current–voltage curves of ZnO nanowire embedded sensors in the ethanol environment and conductances at critical points are inversely proportional to the concentration, while this phenomenon was not observed in the toluol environment. Through individual ZnO nanowire experiments, we attribute negative differential resistance to the joint effect of electron transference in the oxidation process of hydroxyls and the nonequilibrium occupation factor for electrons in the process saturating with generation rate of carriers at the ZnO nanowire surface. The inverse variation is associated with the densities of donor and acceptor traps. These results indicate that surface depletion can be beneficial to nanodevices.

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► Negative differential resistance (NDR) was observed by modulating ZnO NW surface.
► In the toluol environment, NDR was not observed, differing from the performance in ethanol.
► The conductance at the critical points is inversely proportional to the ethanol concentration.
► The released electrons at the surface created a potential perpendicular to the surface.
► The nonequilibrium occupation factor for electrons in the oxidation process saturates.