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Redox-based memristor devices, which are considered to have promising nonvolatile memory, mainly operate through the formation/rupture of nanoscale conductive filaments. However, the random growth of conductive filaments is an obstacle for the stability of memory devices and the cell-to-cell uniformity. Here, we investigate the guiding effect of nanoindentation on the growth of conductive filaments in resistive memory devices. The nanoindented top electrodes generate an electric field concentration and the resultant precise control of a conductive filament in two typical memory devices, Ag/SiO/Pt and W/TaO/Pt. The nanoindented cells possess a much larger ON/OFF ratio, a sharper RESET process, a higher response speed, and better cell-to-cell uniformity compared with the conventional cells. Our finding reflects that the use of large-scale nanotransfer printing might be a unique way to improve the performance of resistive random access memory.

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Two-terminal selectors with high nonlinearity, based on bidirectional threshold switching (TS) behaviors, are considered as a crucial element of crossbar integration for emerging nonvolatile memory and neuromorphic network. Although great efforts have been made to obtain various selectors, existing selectors cannot fully satisfy the rigorous standard of assorted memristive elements and it is in great demand to enhance the performance. Here, a new type of Ag/TaO x /TaO y /TaO x /Ag (x < y) selector based on homogeneous trilayered oxides is developed to attain the required parameters including bidirectional TS operation, a large selectivity of ≈10 10 , a high compliance current up to 1 mA, and ultralow switching voltages under 0.2 V. Tunable operation voltages can be realized by modulating the thickness of inserted TaO y . All-TaO x -based integrated 1S1R (one selector and one memristor) cells, prepared completely by magnetron sputtering and no need of a middle electrode, exhibit a nonlinear feature, which is quite characteristic for the crossbar devices, avoiding undesired crosstalk current issues. The tantalum-oxidebased homojunctions offer high insulation, low ion mobility, and rich interfaces, which is responsible for the modulation of Ag conductive filaments and corresponding high-performance cation-based selector. These findings might advance practical implementation of two-terminal selectors in emerging memories, especially resistive random access memories.tile memory and neuromorphic computing applications. [1] These applications are generally based on the crossbar array structure, where crosstalk current issues notoriously impede the read-write operations. [2] A great deal of efforts have been made to address the critical issue, and the two-terminal selector stands out for their simple structure and no need to compromise the scalability from numerous solutions. [3] Figure 1a illustrates the configuration of 1S1R (one selector and one memristor) integrated crossbar arrays. Recently, various selector elements have been introduced, including Schottky diodes, [4] metal-insulator transition, [5] fieldassisted superlinear threshold, [6] mixedionic-electronic conduction, [7] thermionic/ tunneling emission, [8] and electrochemical-metallization-based (ECM) threshold switching (TS). [9] One Schottky diode cascaded with one memristor (namely, 1D1R) is confined only to unipolar RRAM due to the unilateral conductivity of diodes. Selectors based on transport of ions and electrons are applicable to both unipolar and bipolar RRAM, but the gradually varied voltage-current (I-V) curves predestinates the moderate nonlinearity, [3b] which is not sufficient for the application of RRAM crossbar arrays.The ECM-based selector, which is based on the formation/ diffusion and Rayleigh instability of conductive filaments Nonvolatile MemoryThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.