The influence of surface chemical dynamics on electrical and optical properties of ZnO nanowire field effect transistors.

We demonstrate the effect of surface chemical dynamics on carrier transport and recombination processes of electron-hole pairs in ZnO nanowire field effect transistors. We have found that the electrical conductance decreases and the threshold voltages shift in a positive gate voltage direction, as electrical characteristics are measured repeatedly. We associate this with the enhancement of oxygen adsorption by capturing electrons from the induced current during the probing. This results in an overall depletion of electrons and thus causes the positive shift in threshold voltages associated with the origin and width of characteristic hysteresis loops. In addition, the surface environment dependence of the photo-response related to a recombination process in ZnO nanowires is discussed in terms of the surface chemical reaction and band bending.