RESUMO
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.
RESUMO
In this study, cobalt-doped hexagonal phase WO3 nanorods were prepared by a template-free hydrothermal method. The effects of varying the cobalt doping concentration on the microscopic morphology and electrochromic properties of hexagonal phase WO3 films were investigated. Films synthesized with the optimal cobalt element doping concentration demonstrate a notable improvement in their electrochromic properties compared to the pure hexagonal phase WO3 films. The film doped with 1.5% Co exhibited excellent cycling stability, retaining 98.55% of its original value after 500 cycles. The introduction of cobalt results in the formation of a nanorod structure with a high specific surface area within the film. This structure provides additional reaction sites for the electrochromic reaction process, thereby enhancing the optical modulation and coloration efficiency of WO3. The resulting films with excellent electrochromic properties provide a convenient and effective means for ion-doped modification of WO3-based electrochromic films.