Influence of the measurement procedure on the field-effect dependent conductivity of ZnO nanorods

The electrical properties of field-effect transistors fabricated on the basis of single ZnO nanorods were analyzed under ambient conditions and in the chamber of a scanning electron microscope under high-vacuum conditions. Under ambient conditions, the threshold voltage and conductivity may depend strongly on the details of the measurement procedure as the chosen gate voltage range and gate voltage sweep direction. Electron irradiation in a scanning electron microscope under high-vacuum conditions at ∼10−5 mbar leads to desorption of oxygen and other electronegative molecules, which can increase the conductivity by more than two orders of magnitude.