Ultralow Off-State Current and Multilevel Resistance State in Van der Waals Heterostructure Memristors

Memristors based on 2D semiconductors hold great promise due to their atomic-level thickness and tunable optoelectronic properties. However, a significant challenge lies in suppressing the large off-state current, which leads to additional standby power consumption. Here, a simple and versatile method is presented to address this issue by introducing a thin h-BN interlayer between 2D semiconductors and the electrodes. The thickness of the h-BN interlayer serves as a pivotal parameter for modulating the interfacial Schottky barrier, thereby influencing the off-state current level. This fabricated graphene/alpha-In2Se3/h-BN/Cr-Au memristor, forming a van der Waals heterostructure, exhibits unipolar resistive switching behavior. Remarkably, the memristor incorporating an 8 nm h-BN interlayer showcases an ultralow off-state current of 4.2 x 10-13 A, five orders of magnitude lower than that without the h-BN interlayer. It also achieves a current switching on/off ratio of up to 109 and realizes 32 distinct resistance states, enabling robust multi-bit memory capabilities. Excellent stability and durability are maintained due to the self-encapsulation of the h-BN interlayer. Furthermore, this method is also applicable to memristors built on HfS2, WS2, and WSe2, highlighting its broad potential for technological applications. Owing to the atomic thickness, memristors based on 2D semiconductors show a high off-state current, which leads to additional power consumption. This work designs a versatile device structure to achieve an ultralow off-state current in alpha-In2Se3 memristors by incorporating a thin h-BN interlayer. It also realizes 32 distinct resistance states, enabling robust multi-bit memory capabilities.image