Achieving both positive and negative persistent photocurrent in InSe/GaSe van der Waals heterostructure by introducing amorphous Ga2O3−x

Abstract

Oxidation of environmentally sensitive van der Waals (vdWs) materials or heterostructures can enrich the functionalities of nano-electronic devices by tailoring the band diagram at the hetero-interface. Herein, we demonstrated that amorphous Ga2O3−x with wide-bandgap and insulating features, homogeneously oxidized from GaSe, can act as a tunneling layer in GaSe/InSe vdWs heterostructure device with a floating gate architecture, endowing the robust charge trapping/releasing ability, leading to the achievement of both positive and negative persistent photocurrent (PPC and NPC) characteristics. More impressively, the NPC exhibited OFF/ON current ratio of up to 107, several orders of magnitude larger than the reported NPC in other vdWs materials and heterostructures devices, leading to the achievement of optical memory with 14 distinct current levels and power consumption low to ∼1 pJ. Our work provides an effective avenue to achieve functionality-oriented memory devices by extending this simple configuration to other types of environmentally sensitive vdWs materials.