Formation of the Conducting Filament in TaOx-Resistive Switching Devices by Thermal-Gradient-Induced Cation Accumulation
- Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Materials Science and Engineering
- National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Electrical and Computer Engineering
Here, the distribution of tantalum and oxygen ions in electroformed and/or switched TaOx-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 oxide memory cells.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- 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)
- Grant/Contract Number:
- AC05-00OR22725; 1409068; MCF-677785
- OSTI ID:
- 1460170
- Journal Information:
- ACS Applied Materials and Interfaces, Vol. 10, Issue 27; ISSN 1944-8244
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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