Title: Formation of the Conducting Filament in TaO_x-Resistive Switching Devices by Thermal-Gradient-Induced Cation Accumulation

Abstract

Here, the distribution of tantalum and oxygen ions in electroformed and/or switched TaO_x-based resistive switching devices has been assessed by high-angle annular dark-field microscopy, X-ray energy-dispersive spectroscopy, and electron energy-loss spectroscopy. The experiments have been performed in the plan-view geometry on the cross-bar devices producing elemental distribution maps in the direction perpendicular to the electric field. The maps revealed an accumulation of +20% Ta in the inner part of the filament with a 3.5% Ta-depleted ring around it. The diameter of the entire structure was approximately 100 nm. The distribution of oxygen was uniform with changes, if any, below the detection limit of 5%. We interpret the elemental segregation as due to diffusion driven by the temperature gradient, which in turn is induced by the spontaneous current constriction associated with the negative differential resistance-type I–V characteristics of the as-fabricated metal/oxide/metal structures. A finite-element model was used to evaluate the distribution of temperature in the devices and correlated with the elemental maps. In addition, a fine-scale (~5 nm) intensity contrast was observed within the filament and interpreted as due phase separation of the functional oxide in the two-phase composition region. Understanding the temperature-gradient-induced phenomena is central to the engineering of oxidemore » memory cells.« less

Authors:

Ma, Yuanzhi  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-9901-7659"

Li, Dasheng ^[1]; Herzing, Andrew A. ^[2]; Cullen, David A.  ^[3];

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• Search DOE PAGES for ORCID "0000-0002-2593-7866"

Sneed, Brian T.  ^[3];

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• Search DOE PAGES for ORCID "0000-0002-5656-6180"

More, Karren L.  ^[3];

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• Search DOE PAGES for ORCID "0000-0001-5223-9097"

Nuhfer, N. T. ^[1]; Bain, James A. ^[4]; Skowronski, Marek  ^[1]

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• Search DOE PAGES for ORCID "0000-0002-2087-0068"

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+ Show Author Affiliations

1. Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Materials Science and Engineering
2. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
4. Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Electrical and Computer Engineering

Publication Date:

Mon Jun 18 00:00:00 EDT 2018

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities Division; Semiconductor Research Corp. (SRC), Durham, NC (United States). Microelectronics Advanced Research Corp. (MARCO); Defense Advanced Research Projects Agency (DARPA); National Science Foundation (NSF)

OSTI Identifier:

1460170

Grant/Contract Number:  

AC05-00OR22725; 1409068; MCF-677785

Resource Type:

Accepted Manuscript

Journal Name:

ACS Applied Materials and Interfaces

Additional Journal Information:

Journal Volume: 10; Journal Issue: 27; Journal ID: ISSN 1944-8244

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; 47 OTHER INSTRUMENTATION; filament; modeling; resistive switching; Soret effect; TEM; XEDS