Filament Formation in TaO_x Thin Films for Memristor Device Application: Modeling Electron Energy Loss Spectra and Electron Transport

Abstract

Although understanding filament formation in oxide‐based memristive devices by theory has emerged, there are still fundamental unanswered questions. Importantly, for practical application of thin films the material in its amorphous state is to be considered, but mostly lacking so far, and details on sub‐stoichiometry are also scarce. To gain insight into the optical and electronic properties of sub‐stoichiometric amorphous tantalum oxide (TaOx), the electron energy loss spectrum (EELS) of model systems is characterized theoretically and electron transport characteristics are analyzed in detail. Calculated blue‐shifts by increasing sub‐stoichiometry explained the measurements, potentially suggesting estimation of oxygen vacancy concentrations through EEL spectra. Electron transport results based on TaOx material models validated by EELS measurements show that oxygen vacancy filamentary paths are initiated at low bias upon increasing sub‐stoichiometry yet noting an interplay with the local amorphous structure. Contact resistances at interfaces of the TaOx switching layer and a tantalum scavenging layer or titanium nitride electrode are quantified, indicating the possibility for either oxygen vacancy‐ or metal cluster‐based conduction mechanisms at the interface. The computational work, combined with experimental characterization for validation, provides a basis for investigating effects of sub‐stoichiometry on filament formation in TaOx thin film memristive devices.

N-Doped Graphene/MXene Nanocomposite as a Temperature-Adaptive Neuromorphic Memristor

“…The model of the conductive filament in memristors was proposed according to the first-principles simulations that have been reported elsewhere. The literature found that the principle can be used to predict filament formation, which enables the regulation of operational voltages and improvement in uniformity of memristors, leading to a foundational understanding of performance optimization. , Figure illustrates the probable working mechanism schematic diagram of the fabricated memristor at several different temperatures. Figure a shows conducting filament formation at RT.…”

“…The literature found that the principle can be used to predict filament formation, which enables the regulation of operational voltages and improvement in uniformity of memristors, leading to a foundational understanding of performance optimization. 59,60 Figure 9 illustrates the probable working mechanism schematic diagram of the fabricated memristor at several different temperatures.…”

Oxide‐Based Electrolyte‐Gated Transistors with Stable and Tunable Relaxation Responses for Deep Time‐Delayed Reservoir Computing

“…TaO x has stable amorphous phase and adaptive lattice rearrangements of oxygen vacancies among metal oxides, which is beneficial to the device's stability. [36,37] The 𝛼-IGZO film serves as an ideal channel layer in thin film transistors due to its high electron mobility. [38] The short-term plasticity and stable, tunable relaxation responses are explored in detail.…”