Observation of negative photoconductance in van der Waals heterostructures

Van der Waals (vdW) heterostructures made of different two-dimensional (2D) materials exhibit interesting optoelectronic properties. For example, photodetection and photo-controllable memory devices are two of intriguing applications based on vdW heterostructures. However, the operating principle for most of these devices rely on the positive photoconductance (PPC) effect. Negative photoconductance (NPC) has not yet been observed in vdW heterostructures, which holds promise in constructing optoelectronic devices with low power consumption and high-speed frequency response. In this work [1], we for the first time observed the NPC phenomenon in ReS₂/h-BN/MoS₂ vdW heterostructures-based floating gate phototransistor. The devices show excellent memory properties. More importantly, we realized the transition between the PPC and the NPC in the floating gate phototransistor. With these findings, the vdW heterostructures may open up a novel avenue for the fabrication of photoelectronic nonvolatile memory devices and multifunctional photoconductive devices.

[1] Yu Wang, et al. ACS Nano 12, 9513-9520 (2018).