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.