UV light controlled optoelectronic memory based on WSe2 and hBN encapsulated graphene heterostructures

Abstract

In recent times, 2D materials-based heterostructures are extensively studied for fabricating different nanodevices. Among these materials, transition metal dichalcogenides (TMDC), hexagonal boron nitride (hBN), and graphene (Gr) are widely used in these devices. Optoelectronic memory devices based on 2D materials are among the recently studied devices for structural flexibility and device size miniaturization. In this study, a non-volatile optoelectronic memory device has been fabricated using tungsten diselenide (WSe2), and hBN-encapsulated Gr-based heterostructures. This device can be easily controlled with UV light and an electric field. Two points were focused on in this study; first, the doping state was changed partially i.e., by illuminating a part of the WSe2 layer by UV light and a p-n homo-junction was created. This phenomenon occurs due to the unique structure of Wse2/hBN and the p-n junction could be created in one layer. Secondly, Gr has been used as a floating gate to increase the retention time as Gr is acting as a charge trapping layer. The retention time is further increased due to the thickness of hBN because the defect states keep increasing the charges together.