Observing topotactic phase transformation and resistive switching behaviors in low power SrCoOx memristor

Abstract

Recently, complex oxides have been shown to be promising candidate in dielectric materials of resistive random access memory (RRAM). However, the detailed switching information of complex oxide RRAM is still insufficient, and direct observation of the whole switching process is required to figure out the mechanism. In this study, we deposited SrCoOx (SCO) on a niobium-doped SrTiO3 substrate as the dielectric layer via pulsed laser deposition (PLD). The novel SCO device possesses excellent RRAM properties, high cycling endurance, a long data retention time, and uniform distributions of the high resistance state (HRS) and low resistance state (LRS) resistance and Set/Reset voltage. Furthermore, the switching mechanism was investigated by using transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM), which showed that the switching behavior resulted from the topotactic phase transformation. In addition, the whole switching process was observed through in situ TEM, and the results strengthened the findings of the ex situ experiment. The discussion of this switching behavior provides support for a novel aspect of the RRAM switching mechanism and also a new option for the dielectric material in RRAM.