Performance‐Enhancing Selector via Symmetrical Multilayer Design

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 ≈10¹⁰, 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‐oxide‐based 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.