title: Conduction Channel Formation and Dissolution Due to Oxygen Thermophoresis/Diffusion in Hafnium Oxide Memristors.
abstract: Transition-metal-oxide memristors, or resistive random-access memory (RRAM) switches, are under intense development for storage-class memory because of their favorable operating power, endurance, speed, and density. Their commercial deployment critically depends on predictive compact models based on understanding nanoscale physicochemical forces, which remains elusive and controversial owing to the difficulties in directly observing atomic motions during resistive switching, Here, using scanning transmission synchrotron X-ray spectromicroscopy to study in situ switching of hafnium oxide memristors, we directly observed the formation of a localized oxygen-deficiency-derived conductive channel surrounded by a low-conductivity ring of excess oxygen. Subsequent thermal annealing homogenized the segregated oxygen, resetting the cells toward their as-grown resistance state. We show that the formation and dissolution of the conduction channel are successfully modeled by radial thermophoresis and Fick diffusion of oxygen atoms driven by Joule heating. This confirmation and quantification of two opposing nanoscale radial forces that affect bipolar memristor switching are important components for any future physics-based compact model for the electronic switching of these devices.
authors.affiliation: Hewlett-Packard Laboratories , 1501 Page Mill Road, Palo Alto, California 94304, United States.
authors.forename: Suhas
authors.identifier: 0000-0002-6772-7250
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Stanford University , Stanford, California 94305, United States.
authors.forename: Ziwen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Hewlett-Packard Laboratories , 1501 Page Mill Road, Palo Alto, California 94304, United States.
authors.forename: Xiaopeng
authors.initials: X
authors.lastname: Huang
authors.affiliation: Hewlett-Packard Laboratories , 1501 Page Mill Road, Palo Alto, California 94304, United States.
authors.forename: Niru
authors.initials: N
authors.lastname: Kumari
authors.affiliation: Hewlett-Packard Laboratories , 1501 Page Mill Road, Palo Alto, California 94304, United States.
authors.forename: Noraica
authors.initials: N
authors.lastname: Davila
authors.affiliation: Hewlett-Packard Laboratories , 1501 Page Mill Road, Palo Alto, California 94304, United States.
authors.forename: John Paul
authors.initials: JP
authors.lastname: Strachan
authors.affiliation: Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: David
authors.initials: D
authors.lastname: Vine
authors.affiliation: Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: A L David
authors.initials: AL
authors.lastname: Kilcoyne
authors.affiliation: Stanford University , Stanford, California 94305, United States.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Nishi
authors.affiliation: Hewlett-Packard Laboratories , 1501 Page Mill Road, Palo Alto, California 94304, United States.
authors.forename: R Stanley
authors.initials: RS
authors.lastname: Williams
keywords: filament; memristors; operating mechanism; oxygen migration; thermophoresis