Electrical properties and current conduction mechanisms of LaGdO₃ thin film by RF sputtering for RRAM applications

Amorphous LaGdO3 (LGO) thin films were deposited by using RF sputtering system and unipolar resistive switching (URS) properties in the Al/LGO/ITO structure were investigated. The influences of Ar/O2 ratio, film thickness, postannealing condition, and electrode on the RS properties were also studied. The conductive filaments are mostly related to the numbers of oxygen vacancies that can be controlled through a different deposition atmosphere Ar/O2 ratio and film thickness. In addition, the RS characteristics and operating voltage can be improved by postannealing treatment. It is suggested that the In ions diffused from ITO participated in the formation of the filaments of the RRAM. The low resistance state (LRS) and high resistance state (HRS) conduction mechanism in the device were dominated by the Ohmic behavior and Schottky emission, respectively. Also, the RS characteristic is significantly affected by the potential barrier height between top electrode and LGO. The proposed RRAM exhibits unipolar resistive switching characteristic for over 400 times switching cycles and high stable retention characteristic for over 104 seconds with a resistance ratio (RHRS/RLRS) of around 4 orders.