Resistive Switching in Au/TiO2/Pt Thin Film Structures

The paper reports on the conditions of, and the mechanisms involved in pretreatment by strong electric field ("forming") and subsequent resistive switching in Au/TiO2/Pt thin film structures on silicon. The thin TiO2 films in these structures were prepared by different methods, namely, vacuum evaporation of metallic titanium followed by its thermal oxidation in air, and RF cathode sputtering of titanium dioxide from a powder target. Current-voltage and voltage-capacitance characteristics of the structures, as well as the relations connecting their conductivity with hold time under dc voltage of different polarities and temperature have been measured. The data obtained permit a conclusion that the physical mechanism underlying the forming consists in a sharp increase of the density of surface states in TiO2 films initiated by electric breakdown of the Schottky barrier at the contact with the platinum electrode, while the resistive switching of the structures is governed by the variation of the occupation of surface states in the TiO2 band gap and/or of defect concentration in the barrier region under the action of electric field.