Transient drain current characteristics of ZnO nanowire field effect transistors

We investigated the characteristics of the time-dependent drain current of ZnO nanowire field effect transistors (FETs). The drain current of ZnO nanowire FETs in ambient air decreases from an initial current level in the microampere range and saturates to the 1-100 nA range in tens of seconds. This transient phenomenon is ascribed to electrically interactive adsorption of oxygen ions to the nanowire surface. Exposure to ambient air during positive gate biasing reduces the conduction channel width by extending the depletion region, resulting in a higher resistivity with conduction only through the narrower nanowire core. (C) 2009 American Institute of Physics. [doi:10.1063/1.3232203]