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Stable Metallic Enrichment in Conductive Filaments in TaO x ‐Based Resistive Switches Arising from Competing Diffusive Fluxes
Author(s) -
Ma Yuanzhi,
Goodwill Jonathan M.,
Li Dasheng,
Cullen David A.,
Poplawsky Jonathan D.,
More Karren L.,
Bain James A.,
Skowronski Marek
Publication year - 2019
Publication title -
advanced electronic materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.25
H-Index - 56
ISSN - 2199-160X
DOI - 10.1002/aelm.201800954
Subject(s) - protein filament , materials science , amorphous solid , resistive random access memory , anode , electrical conductor , nanotechnology , resistive touchscreen , electrode , chemical physics , optoelectronics , condensed matter physics , crystallography , composite material , chemistry , physics , electrical engineering , engineering
Oxide‐based resistive‐switching devices hold promise for solid‐state memory technology. Information encoding is accomplished by electrically switching the device between two nonvolatile states with low and high resistance states (LRS/HRS). It is generally accepted that the change between these states is due to the motion of oxygen vacancies forming a continuous (LRS) or gapped (HRS) filament between the electrodes. Direct assessments of filaments are rare due to their small size and the difficulty of locating the filament. Electron microscopy experiments reveal the filament structure and chemistry in TaO 2.0 ± 0.2 ‐based 150 × 150 nm 2 devices with cross‐sectional geometry after forming with power dissipation lower than 1 mW. The filaments appear to be roughly hourglass‐shaped with a diameter of less than 10 nm and are composed of Ta‐rich and O‐poor mostly amorphous material with local compositions as Ta‐rich as TaO 0.4 . The as‐formed HRS has a gap up to 10 nm wide located next to the anode and composed of nearly stoichiometric TaO 2.5 . The tantalum and oxygen distribution is consistent with filaments formed by the motion of both Ta and O driven by temperature gradients (Soret effect) and an electric field. This interpretation points towards a new compact model of resistive‐switching devices.