| 초록 |
Memcapacitors have been paid attention as an candidate of high-density information storage memory devices in novel semiconductor electronics. The memcapacitors feature multilevel, modulated capacitance and long-term retention without an external electric-field. Generally, it is expected that the memcapacitive behaviors accompanied memristive behaviors. Thus, the BiFeO3, which shows a memristive properties, is a candidate material to demonstrate the memcapacitive behavior. Here we demonstrated the memcapacitor behaviors of multilevel and modulated capacitance in the BiFeO3 thin films. Firstly, we fabricated BiFeO3/SrRuO3 bilayer epitaxial thin films grown on the SrTiO3 (001) substrate via pulsed laser deposition. We observed the modulated the four distinguishable capacitance states with an on/off ratio of 20% depending on external bias-voltage. In particular, such multilevel capacitive states show repeatable, reproducible in the Pt/BiFeO3/SrRuO3 capacitor structure. Based on the X-ray photoelecron spectroscopy results of the BiFeO3/SrRuO3 thin film, the origin of memcapacitive properties of the Pt/BiFeO3/SrRuO3 capacitor structure will be discussed with change of Fe oxidation state and the presence of oxygen vacancies of the BiFeO3 layers. Our results provide a framework to demonstrate the memcapacitor behaviors in the epitaxial BiFeO3 thin films. |
