title: Understanding the conductive channel evolution in Na:WO(3-x)-based planar devices.
abstract: An ion migration process in a solid electrolyte is important for ion-based functional devices, such as fuel cells, batteries, electrochromics, gas sensors, and resistive switching systems. In this study, a planar sandwich structure is prepared by depositing tungsten oxide (WO(3-x)) films on a soda-lime glass substrate, from which Na(+) diffuses into the WO(3-x) films during the deposition. The entire process of Na(+) migration driven by an alternating electric field is visualized in the Na-doped WO(3-x) films in the form of conductive channel by in situ optical imaging combined with infrared spectroscopy and near-field imaging techniques. A reversible change of geometry between a parabolic and a bar channel is observed with the resistance change of the devices. The peculiar channel evolution is interpreted by a thermal-stress-induced mechanical deformation of the films and an asymmetric Na(+) mobility between the parabolic and the bar channels. These results exemplify a typical ion migration process driven by an alternating electric field in a solid electrolyte with a low ion mobility and are expected to be beneficial to improve the controllability of the ion migration in ion-based functional devices, such as resistive switching devices.
authors.affiliation: I. Physikalisches Institut (IA), RWTH Aachen University, 52074 Aachen, Germany. taubner@physik.rwth-aachen.de wuttig@physik.rwth-aachen.de.
authors.forename: Dashan
authors.initials: D
authors.lastname: Shang
authors.forename: Peining
authors.initials: P
authors.lastname: Li
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Egidio
authors.initials: E
authors.lastname: Carria
authors.forename: Jirong
authors.initials: J
authors.lastname: Sun
authors.forename: Baogen
authors.initials: B
authors.lastname: Shen
authors.forename: Thomas
authors.initials: T
authors.lastname: Taubner
authors.forename: Ilia
authors.initials: I
authors.lastname: Valov
authors.forename: Rainer
authors.initials: R
authors.lastname: Waser
authors.forename: Matthias
authors.initials: M
authors.lastname: Wuttig