One-Selector-One-Resistor\nIntegrated Memory Cells\nBased on Two-Dimensional Heterojunction Memory Selectors

Selectors are critical components for reducing the sneak\npath leakage\ncurrents in emerging resistive random-access memory (RRAM) arrays.\nTwo-dimensional (2D) materials provide a rich choice of materials\nwith van der Waals stacking to form the heterostructure selectors\nwith controllable energy barriers. Here, we experimentally demonstrate\n2D-material-based heterostructure selectors with exponential current–voltage\n(<i>I</i>–<i>V</i>) relationships and integrate\nthem with hafnium oxide (HfO<sub><i>x</i></sub>)-based RRAMs,\nforming one-selector-one-resistor (1S1R) cells. The multilayer graphene\n(MG)/tungsten disulfide (WS<sub>2</sub>)/platinum (Pt) selector contains\ntwo asymmetric heterojunctions with different Schottky barriers, which\nlead to highly nonlinear and asymmetric <i>I</i>–<i>V</i> characteristics. The 2D selectors in 1S1R cells can successfully\ndrive RRAMs, reduce sneak path leakage current by more than 100 times,\nand provide the set compliance current. The 1S1R cells are further\nmodeled and integrated into both planar and 3D memory arrays, with\ncircuit-level simulations demonstrating that the presence of 2D selectors\nin large memory arrays can reduce the power consumption by up to 86%,\nimprove the read/write margin by up to 31%, and avoid write failure.\nSuch a platform holds high potential for constructing 3D high-density\nmemories and performing in-memory computing.