The Impact of Y Addition into TiO2 on Electronic States and Resistive Switching Characteristics

Abstract

We have studied electronic structures and resistive switching characteristics of Y-doped TiO2 films as a function of Y content to improve the performance on resistive switching of TiO2-based ReRAM. TiYxOy films with different Y contents were deposited on a Pt layer by metal organic chemical vapor deposition (MOCVD) using dipivaloymethanato (DPM) precursors and followed by O2 anneal to densify the films. A fairly good compositional uniformity in each TiYxOy film was confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The energy bandgap (Eg) of the TiYxOy films, which was determined by analyzing the absorption coefficient, was gradually increased with the Y content. Since a decrease in valence band offset between TiYxOy and Pt was almost the same as that in Eg, the conduction band offset was almost constant at ∼1.3 eV. The current–voltage (I–V) characteristics of TiYxOy films, which were measured by sweeping positive bias to a Au top electrode after forming process, show non-polar type resistive switching and its beneficial change with Y incorporation into the TiO2 matrix. The Y addition is quite effective to improve endurance in resistive switching and to reduce the variations of operation voltages (VSET and VRESET).