期刊
ACS APPLIED MATERIALS & INTERFACES
卷 11, 期 39, 页码 36232-36243出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.9b10705
关键词
DFT; oxygen diffusion; ReRAM; electroforming; silicon dioxide; titanium nitride
资金
- UK Engineering and Physical Sciences Research Council (EPSRC) [EP/K01739X/1, EP/P013503/1]
- Leverhulme Trust [RPG-2016-13S]
- EPSRC [EP/L015862/1, EP/L000202, EP/R029431]
- COMET program within the K2 Center Integrated Computational Material, Process and Product Engineering (IC-MPPE) [859480]
- Austrian Federal Ministry for Transport, Innovation, and Technology (BMVIT)
- Austrian Federal Ministry for Digital and Economic Affairs (BMDW)
- A*STAR Graduate Academy under the ARAP program
- federal state of Styria
- federal state of Upper Austria
- federal state of Tyrol
- EPSRC [EP/K01739X/1, EP/P013503/1, EP/R029431/1] Funding Source: UKRI
Silica-based resistive random access memory devices have become an active research area due to complementary metal oxide semiconductor compatibility and recent dramatic increases in their performance and endurance. In spite of both experimental and theoretical insights gained into the electroforming process, many atomistic aspects of the set and reset operation of these devices are still poorly understood. Recently a mechanism of electroforming process based on the formation of neutral oxygen vacancies (V-O(0)) and interstitial O ions (O-i(2-)) facilitated by electron injection into the oxide has been proposed. In this work, we extend the description of the bulk (O-i(2-)) migration to the interface of amorphous SiO2 with the polycrystaline TiN electrode, using density functional theory simulations. The results demonstrate strong kinetic and thermodynamic drive for the movement of O-i(2-) to the interface, with dramatically reduced incorporation energies and migration barriers close to the interface. The arrival of O-i(2-) at the interface is accompanied by preferential oxidation of undercoordinated Ti sites at the interface, forming a Ti-O layer. We investigate how O ions incorporate into a perfect and defective Sigma 5(012)[100] grain boundary (GB) in TiN oriented perpendicular to the interface. Our simulations demonstrate the preferential incorporation of O-i at defects within the TiN GB and their fast diffusion along a passivated grain boundary. They explain how, as a result of electroforming, the system undergoes very significant structural changes with the oxide being significantly reduced, interface being oxidized, and part of the oxygen leaving the system.
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