Schottky barrier height modulation and photoconductivity in a vertical graphene/ReSe2 vdW p-n heterojunction barristor

Abstract

A 3-terminal device with a tunable Schottky barrier controls the charge transport across a vertically stacked structure named “barristor”- one composed of a graphene/rhenium diselenide (ReSe2) p-n heterojunction to exploit the advantages of the high mobility of graphene with tunable ReSe2 for digital applications is reported herein. The CVD-graphene used to fabricate p-n heterojunction with ReSe2 is p-type doped by DUV irradiation in O2 atmosphere for 30 min. Density functional theory (DFT) calculations reveals highly anisotropic behavior of ReSe2, possessing bandgap of 1.17 eV. We demonstrate that the gate-controlled Schottky barrier can be utilized to modify carrier transport in graphene, resulting in tuning of the Schottky barrier height. Thus, by modulating the work function of the monolayered graphene via the back-gate voltages, the Schottky barrier height at the interface between the graphene and ReSe2 could be varied by up to 300 meV. A diode showed good rectification behavior with an ON/OFF current ratio of 102. Furthermore, the barristor exhibits good optoelectronic characteristics with a sensing range from visible (455 nm) to near IR (850 nm) and is capable of detecting low incident power density. The diode attained photoresponsivity and detectivity values of 42 AW-1 and 2.2 × 1012 Jones, respectively, and a rise time of 33.94 ms under 656 nm laser illumination. Our approach could aid the improved development of high-performance graphene-based heterojunction devices.