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Department of Electrical Engineering-Electrophysics, University of Southern California, Los Angeles, California, USA
Address for correspondence: C. Zhou, Dept. of E.E.-Electrophysics, University of Southern California, Los Angeles, CA 90089, USA. chongwuz{at}usc.edu Ann. N.Y. Acad. Sci. 1006: 104-121 (2003).
Single-crystalline indium oxide nanowires were synthesized using a laser ablation method and characterized using various techniques. Precise control over the nanowire diameter down to 10 nm was achieved by using monodisperse gold clusters as the catalytic nanoparticles. In addition, field effect transistors with on/off ratios as high as 104 were fabricated based on these nanowires. Detailed electronic measurements confirmed that our nanowires were n-type semiconductors with thermal emission as the dominating transport mechanism, as revealed by temperature-dependent measurements. Furthermore, we studied the chemical sensing properties of our In2O3 nanowire transistors at room temperature. Upon exposure to a small amount of NO2 or NH3, the nanowire transistors showed a decrease in conductance of up to five or six orders of magnitude, in addition to substantial shifts in the threshold gate voltage. Our devices exhibit significantly improved chemical sensing performance compared to existing solid-state sensors in many aspects, such as the sensitivity, the selectivity, the response time and the lowest detectable concentrations. We have also demonstrated the use of UV light as a "gas cleanser" for In2O3 nanowire chemical sensors, leading to a recovery time as short as 80 seconds.
Key Words: indium oxide • nanowire • transistor • chemical sensor
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