title: Air-pressure tunable depletion width, rectification behavior, and charge conduction in oxide nanotubes.
abstract: Metal-oxide nanotubes provide large surface areas and functionalizable surfaces for a variety of optical and electronic applications. Here we report air-tunable rectifying behavior, depletion width modulation, and two-dimensional (2D) charge conduction in hollow titanium-dioxide nanotubes. The metal contact forms a Schottky-diode in the nanotubes, and the rectification factor (on/off ratio) can be varied by more than 3 orders of magnitude (1-2 × 10(3)) as the air pressure is increased from 2 mTorr to atmospheric pressure. This behavior is explained using a change in depletion width of these thin nanotubes by adsorption of water vapor on both surfaces of a hollow nanotube, and the resulting formation of a metal-insulator-semiconductor (MIS) junction, which controls the 2D charge conduction properties in thin oxide nanotubes.
authors.affiliation: Department of Chemical and Biological Engineering, ‡Materials Science and Engineering, and §Renewable and Sustainable Energy Institute, University of Colorado , Boulder, Colorado, United States.
authors.forename: Yahya
authors.initials: Y
authors.lastname: Alivov
authors.forename: Hans H
authors.initials: HH
authors.lastname: Funke
authors.forename: Vivek
authors.initials: V
authors.lastname: Singh
authors.forename: Prashant
authors.initials: P
authors.lastname: Nagpal
keywords: Schottky diode; air-gating; air-tunable rectification; chemical diodes; metal-oxide nanotubes