Atomistic Insights on the Full Operation Cycle of a HfO2-Based Resistive Random Access Memory Cell from Molecular Dynamics

M. Laura Urquiza, Md Mahbubul Islam, Adri C.T. Van Duin, Xavier Cartoixà, Alejandro Strachan

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish (US)
Pages (from-to)12945-12954
Number of pages10
JournalACS nano
Volume15
Issue number8
DOIs
StatePublished - Aug 24 2021

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Fingerprint

Dive into the research topics of 'Atomistic Insights on the Full Operation Cycle of a HfO<sub>2</sub>-Based Resistive Random Access Memory Cell from Molecular Dynamics'. Together they form a unique fingerprint.

Cite this