Characterization of the inhomogeneity of Pt/CeO_x/Pt resistive switching devices prepared by magnetron sputtering

There are unrevealed factors that bring about the performance variations of resistive switching devices. In this work, Pt/CeO_x/Pt devices prepared by magnetron sputtering showed rectification in their asymmetrical current–voltage (I–V) curves during voltage sweeps. X-ray photoelectron spectroscopy showed that the deposited CeO_x film had an inhomogeneous composition, and more oxygen vacancies existed in CeO_x near the top electrode. The asymmetrical resistance change of the Pt/CeO_x/Pt devices can be explained by the presence of more charged oxygen vacancies in CeO_x near the top electrode, along with the Schottky conduction mechanism. This work reveals that the compositional inhomogeneity is inevitable in the magnetron sputtering of oxide targets like CeO₂ and can be an important source of device-to-device and cycle-to-cycle variations of memristors. (paper)