Gas sensing properties of single-crystalline indium oxide nanowires

Single crystalline In/sub 2/O/sub 3/ nanowires were synthesized and then utilized to construct field effect transistors (FETs) consisting of individual nanowires. Chemical sensors based on these In/sub 2/O/sub 3/ nanowire FETs have been demonstrated. Upon exposure to gaseous molecules such as NO/sub 2/ and NH/sub 3/, the electrical conductance of the In/sub 2/O/sub 3/ nanowire FETs is found to be dramatically modified, accompanied by substantial shifts in the threshold gate voltage. Our In/sub 2/O/sub 3/ nanowire sensors exhibit significantly improved sensitivity to NO/sub 2/ gas, as well as shortened response times compared to most existing solid-state gas sensors. In addition, NH/sub 3/ gas sensing properties of In/sub 2/O/sub 3/ nanowires have also been carefully studied. Change of conductance in opposite directions was observed with different nanowire sensors. We suggest that this differential response is caused by various doping concentrations in the semiconducting In/sub 2/O/sub 3/ nanowires.