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/α-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 × 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.