Switching behavior in rare-earth films fabricated in full room temperature

In this paper, we investigated the forming-free resistive-switching (RS) behavior in the Ru/REO _x/TaN (RE = Ce, Pr, Sm, and Eu) memory device using CeO _x, PrO _x, SmO _x, and EuO _x thin films fabricated in a full-room-temperature process. The dominant conduction mechanism of Ru/REO _x/TaN memory devices in the low-resistance state is ohmic behavior, whereas the high-resistance state is space-charge-limited conduction. The Ru/CeO _x/TaN devices show a high resistance ratio of > 10 ⁴, reliable data retention for 10 ⁵ s, and stable endurance characteristics for up to 1000 cycles. This result suggests the high concentration of the cerium ions and the low density of chemical defects (oxygen vacancies) in the CeO _x film. The Ru/CeO _x/TaN structure memory is a very promising candidate for future nonvolatile RS memory applications.