Passivation effects on ZnO nanowire field effect transistors under oxygen, ambient, and vacuum environments

We investigated the passivation effects on the electrical characteristics of ZnO nanowire field effect transistors (FETs) under the various oxygen environments of ambient air, dry O-2, and vacuum. When the ZnO nanowire FET was exposed to more oxygen, the current decreased and the threshold voltage shifted to the positive gate bias direction, due to electrons trapping to the oxygen molecules at the nanowire surface. On the contrary, the electrical properties of the nanowire FET remained unchanged under different environments with passivation by a polymethyl methacrylate layer, which demonstrates the importance of surface passivation for ZnO nanowire-based electronic device applications. (c) 2008 American Institute of Physics.