Atomistic Insights on the Full Operation Cycle of a HfO2-Based Resistive Random Access Memory Cell from Molecular Dynamics
Urquiza, M. Laura (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Islam, Md Mahbubul (Wayne State University. Department of Mechanical Engineering)
Van Duin, Adri (Pennsylvania State University. Department of Mechanical Engineering)
Cartoixà Soler, Xavier (Universitat Autònoma de Barcelona. Departament d'Enginyeria Electrònica)
Strachan, Alejandro (Purdue University West Lafayette)

Data:	2021
Resum:	We characterize the atomic processes that underlie forming, reset, and set in HfO2-based resistive random access memory (RRAM) cells through molecular dynamics (MD) simulations, using an extended charge equilibration method to describe external electric fields. By tracking the migration of oxygen ions and the change in coordination of Hf atoms in the dielectric, we characterize the formation and dissolution of conductive filaments (CFs) during the operation of the device with atomic detail. Simulations of the forming process show that the CFs form through an oxygen exchange mechanism, induced by a cascade of oxygen displacements from the oxide to the active electrode, as opposed to aggregation of pre-existing oxygen vacancies. However, the filament breakup is dominated by lateral, rather than vertical (along the filament), motion of vacancies. In addition, depending on the temperature of the system, the reset can be achieved through a redox effect (bipolar switch), where oxygen diffusion is governed by the applied bias, or by a thermochemical process (unipolar switch), where the diffusion is driven by temperature. Unlike forming and similar to reset, the set process involves lateral oxygen atoms as well. This is driven by field localization associated with conductive paths.
Ajuts:	Agencia Estatal de Investigación RTI2018-097876-B-C21
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	EChemDID ; Forming-reset-set ; MD ; RRAM ; Valence change mechanism
Publicat a:	ACS nano, Vol. 15, Issue 8 (July 2021) , p. 12945-12954, ISSN 1936-086X

DOI: 10.1021/acsnano.1c01466
PMID: 34329560

10 p, 9.8 MB

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