Superior bipolar resistive switching characteristics of Cu-TiO2 based RRAM cells

Abstract

Resistive random access memory (RRAM) cells with Cu-doped TiO2 film between two Pt inert electrodes are produced in this work, and these achieve a lower required programming voltage of -0.7 V and higher endurance of about 1000 cycles at the programming/erasing voltage of -5 V/+ 3 V for the pulse width of 1 mu s, compared with the conventional Pt/TiO2/Cu ones. It is conjectured that the distribution of Cu sources in the Cu-doped TiO2 (TiO2 : Cu) resistive switching film facilitates the formation of sharp and narrow conductive filaments, attributed to the Cu sources near the negative biased Pt electrode were oxidised more easily to become the Cu cations than those in other regions. The proposed Pt/TiO2 : Cu/Pt sample can thus achieve a lower DC programming voltage than the conventional one. Moreover, it is conjectured that the better endurance of the Pt/TiO2 : Cu/Pt sample is due to the lower amount of residual Cu atoms in the TiO2 layer from the ruptured filaments during the erasing process. This is because the increase in the amount of Cu atoms is limited by the inert Pt electrode when there are uniformly distributed Cu sources and there is no Cu electrode.