Resistive Switching Characteristics of Tantalum Oxide and Titanium Oxide Heterojunction Devices

In this study, single-layer and trilayer devices with Pt/Ti/TaO2/Pt and Pt/Ti/TiOx/TaO2/TiOx/Pt structures were fabricated. For the trilayer device, a tantalum oxide thin film was sandwiched between the titanium oxide thin films. The thickness of the tantalum oxide in the single-layer device was similar to 20 nm. The total trilayer oxide thickness was similar to 17.5 nm. The trilayer heterojunction device exhibited very stable bipolar resistive switching, which could be caused by the formation and rupture of the conducting filaments (CFs) in the oxide switching layers. The trilayer device showed better endurance and retention characteristics and low SET and RESET voltages, with very small variations. The conduction mechanisms of ohmic conduction, space-charge-limited conduction, Poole-Frenkel emission, and Schottky conduction have been investigated as the possible conduction mechanisms for the resistive switching of the devices.