Impact of ultrathin Al2O3 interlayers on resistive switching in TiOx thin films deposited by atomic layer deposition

Abstract

TiOx and TiOx/Al2O3/TiOx sandwiched thin films were fabricated by using atomic layer deposition at 250 °C. As compared to single-layered TiOx, TiOx/Al2O3/TiOx sandwiched thin films exhibit stable resistive switching with a substantially improved OFF/ON ratio and elongated endurance. Essentially, the embedded ultrathin Al2O3 interlayer will suppress the crystallization of amorphous TiOx and thus reduce the channels for current leakage. As a result, the resistive switching properties are substantially enhanced. The TiOx/Al2O3/TiOx sandwiched thin films with the Al2O3 thickness of more than 2 nm show stable unipolar resistive switching, and the rupture and reformation of conductive filaments mainly occur at the top interface between Al2O3 and TiOx layers. A physical model is proposed to understand the resistive switching behaviors.