Multilevel Resistive Switching with Oxygen Vacancy Filaments in Pt/TaO_x/Cu and Pt/TaO_x/Pt Devices

摘要

It is demonstrated that multilevel switching of oxygen vacancy (V_o) conductive filaments (CF) is characterized by the relation R_(on)=A/I_(cc)~n between ON-state resistance (Ron) and compliance current (I_(cc)). In contrast to metallic (Cu, Ag) CFs, where the exponent n for various devices is found universally to be n ≈ 1, we find n=1.36 for V_o CFs. An exponent n＞1 may imply two distinct mechanisms responsible for the formation of V_o CFs. 1st mechanism is similar to the formation mechanism for metallic CFs and accounts for the unity part of the exponent, while the 2nd mechanism is responsible for the remainder (n-1). This hypothesis is corroborated by data of V_o CFs in resistive switching cells with and without active electrodes such as Pt/TaO_x/Cu and Pt/TaO_x/Pt and also on Pt/SiO_2/Cu and Pt/SiO_2/Pt devices.