Field-effect transistors (FETs) based on individual semiconducting oxide (SnO 2 and ZnO) nanobelts with multiterminal electrical contacts have been fabricated and characterized. Simultaneous two-terminal and four-terminal measurements enable direct correlation of the FET characteristics with the nature of the contacts. Devices with high-resistance non-Ohmic contacts exhibit a Schottky barrier FET behavior. In contrast, low-resistance Ohmic contacts on the nanobelt lead to high-performance n-channel depletion mode FETs with well-defined linear and saturation regimes, large "on" current, and an on/off ratio as high as 10 7. The FET characteristics of such devices show a significant modification by a 0.2% H 2 gas flow at room temperature. The excellent intrinsic characteristics of these nanobelt FETs make them ideal candidates as nanoscale biological and chemical sensors based on field-effect modulation of the channel conductance.
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This work was supported by NSF NIRT Grant No. ECS-0210332 and a FSU Research Foundation PEG grant.