Selective activation of memristive interfaces in TaO x -based devices by controlling oxygen vacancies dynamics at the nanoscale

FERREYRA, C; SÁNCHEZ, M J; AGUIRRE, M; ACHA, C; BENGIÓ, S; LECOURT, J; LÜDERS, U; RUBI, D

NANOTECHNOLOGY

IOP PUBLISHING LTD

Año: 2020 vol. 31 p. 155204 - 155216

0957-4484

The development of novel devices for neuromorphic computing and non-traditional logicoperations largely relies on the fabrication of well controlled memristive systems withfunctionalities beyond standard bipolar behavior and digital ON?OFF states. In the presentwork we demonstrate for Ta 2 O 5 -based devices that it is possible to selectively activate/deactivate two series memristive interfaces in order to obtain clockwise or counter-clockwisemultilevel squared remanent resistance loops, just by controlling both the electroformingprocess and the (a)symmetry of the applied stimuli, and independently of the nature of the usedmetallic electrodes. Based on our thorough characterization, analysis and modeling, we showthat the physical origin of this electrical behavior relies on controlled oxygen vacancieselectromigration between three different nanoscopic zones of the active Ta 2 O 5−x layer: acentral one and two quasi-symmetric interfaces with reduced TaO 2−h(y) layers. Our devicesfabrication process is rather simple as it implies the room temperature deposition of only oneCMOS compatible oxide?Ta-oxide?and one metal, suggesting that it might be possible totake advantage of these properties at low cost and with easy scability. The tunable oppositeremanent resistance loops circulations with multiple?analogic?intermediate stable statesallows mimicking the adaptable synaptic weight of biological systems and presents potentialfor non-standard logic devices