Nanofilamentary resistive switching in binary oxide system; a review on the present statusand outlook

Abstract

This review article summarized the recent understanding of resistance switching (RS) behaviorin several binary oxide thin film systems. Among the various RS materials and mechanisms,TiO2 and NiO thin films in unipolar thermo-chemical switching mode are primarilydealt with. To facilitate the discussions, the RS was divided into three parts;electroforming, set and reset steps. After short discussions on the electrochemistry of‘electrolytic’ oxide materials, the general and peculiar aspects of these RS systems andmechanism are elaborated. Although the RS behaviors and characteristics ofthese materials are primarily dependent on the repeated formation and ruptureof the conducting filaments (CFs) at the nanoscale at a localized position, thismechanism appears to offer a basis for the understanding of other RS mechanismswhich were originally considered to be irrelevant to the localized events. Theelectroforming and set switching phenomena were understood as the process of CFformation and rejuvenation, respectively, which are mainly driven by the thermallyassisted electromigration and percolation (or even local phase transition) of defects,while the reset process was understood as the process of CF rupture where thethermal energy plays a more crucial role. This review also contains several remarkson the outlook of these resistance change devices as a semiconductor memory.