Dynamics of Analog Switching Behavior in Thin Polycrystalline Barium Titanate

Abstract

Engineering of interfaces and point defects in ferroelectric memristors is an efficient way for manipulating the resistive switching effects of mixed ionic-electronic nature. However, an interplay between the defects, interfacial properties, and ferroelectric polarization as well as their influence on the resistance state tuning are yet to be revealed. By considering the memristive device built on a thin polycrystalline BaTiO3 film, a drift-diffusion model of non-stationary processes is developed. The model is based on Poisson and continuity equations solved numerically and accounts for various transport mechanisms for electrons, holes, and oxygen vacancies. Comparing simulated resistive effects with experimental data taken in a wide temperature range, it is shown that an appearance of the analog resistive switching cannot be explained solely by oxygen-ionic transport. Investigated switching dynamics claims the oxygen vacancies redistribution to be responsible for the analog character of the switching at the prevalence of the electron hopping transport. Crucially, the required dynamics of the vacancies redistribution is achieved only in a narrow range of their mobility. These results can be used in designing the ferroelectric memristors for nonvolatile multilevel memory devices satisfying the requirements that arise at the stages of their integration into neuromorphic architectures.