Antimony nanowire arrays have been fabricated by template assisted electro-deposition technique. Anodic aluminum oxide membranes with pore diameters around 60-90 nm are used to cast quasi-one dimensional Sb nanostructure. The as-grown Sb nanowires are characterized by electron microscopy and energy dispersive x-ray spectroscopy. Upon their remarkable linear response to hydrogen ion concentration, Sb nanowire arrays are utilized as nanoscale electrodes to determine solution pH value. They demonstrate promising potential for nanoscale solid state sensing device.
Zinc oxide nanowires are configured as <i>n</i>-channel field effect transistors. These transistors are implemented as highly sensitive chemical sensors for detection of various gases such as O<sub>2</sub>, NO<sub>2</sub>, NH<sub>3</sub>, and CO at room temperature. They show oxidizing sensing property to oxygen and nitrogen dioxide. Nanowires' ammonia sensing behavior is observed to switch from oxidizing to reducing when temperature increased from 300 to 500 K. This effect is attributed to the temperature dependent chemical potential shift. Carbon monoxide is found to increase the nanowire conductance in the presence of oxygen. Due to a Debye screening length comparable to the nanowire diameter, the electric field applied over the back gate significantly affects the sensitivity as it modulates the carrier concentration. A strong negative field is utilized to refresh the sensors by an electro-desorption mechanism. In addition, different chemisorbed species could be distinguished from the "refresh" threshold voltage and the temporal response of the conductance. These results demonstrate a refreshable field effect sensor with a potential gas identification function.
Low dimensional systems such as nanotubes and nanowires have fascinating, and technologically useful, optical and electrical properties. Studies on these systems advance our knowledge on the science at the nanoscale, while simultaneously provides the possibility for developing miniaturized electronics and optoelectronics. The material system attracting increasing attention is zinc oxide (ZnO),<sup>1-6</sup>which is a <i>II-VI</i>compound semiconductor with a wide and direct banc gap of 3.37 eV at room temperature. ZnO has demonstrated unique properties and potential applications in manifold fields, such as transparent electronics, ultraviolet (UV) light emitter, surface acoustic wave devices, gas sensors and magnetoelectronics. It is shown to have wurtzite structure with lattice constant a = 3.249 Α, c = 5.207 Α. Its large exciton binding energy (60 meV), which is much greater than the thermal energy at room temperature, makes it a promising candidate for applications in blue-UV light emission and room temperature UV lasing<sup>7</sup>. Furthermore, its high piezoelectric constant (d<sub>33</sub>=246) makes it a highly valuable material for fabricating mechanical devices, such as acoustic transducers, sensors and actuators.
Conference Committee Involvement (3)
Nanosensing: Materials, Devices, and Systems III
11 September 2007 | Boston, MA, United States
Nanomaterials Synthesis, Interfacing, and Integrating in Devices, Circuits, and Systems II
9 September 2007 | Boston, MA, United States
Nanomaterial Synthesis and Integration for Sensors, Electronics, Photonics, and Electro-Optics
1 October 2006 | Boston, Massachusetts, United States