The research on suspended ZnO nanowire field-effect transistor

This paper reports that a novel type of suspended ZnO nanowire field-effect transistors (FETs) were successfully fabricated using a photolithography process, and their electrical properties were characterized by $I$--$V$ measurements. Single-crystalline ZnO nanowires were synthesized by a hydrothermal method, they were used as a suspended ZnO nanowire channel of back-gate field-effect transistors (FET). The fabricated suspended nanowire FETs showed a p-channel depletion mode, exhibited high on--off current ratio of $\sim$10$^{5}$. When $V_{\rm DS}=2.5$\,V, the peak transconductances of the suspended FETs were 0.396\,$\mu $S, the oxide capacitance was found to be 1.547\,fF, the pinch-off voltage $V_{\rm TH}$ was about 0.6\,V, the electron mobility was on average 50.17\,cm$^{2}$/Vs. The resistivity of the ZnO nanowire channel was estimated to be $0.96\times 10^{2}~\Omega $\,cm at $V_{\rm GS} = 0$\,V. These characteristics revealed that the suspended nanowire FET fabricated by the photolithography process had excellent performance. Better contacts between the ZnO nanowire and metal electrodes could be improved through annealing and metal deposition using a focused ion beam.