Maximizing Schottky barrier modulation in graphene-WSe₂/MoSe₂ heterojunction barristor through Dirac-cone induced phenomenon

Graphene barristors, employing monolayer graphene on a dielectric material, stand out for their ability to modulate the Schottky barrier via gate voltage (V-GS). However, most of barristor devices are hindered by low ON/OFF current ratio (<10(3)similar to 10(4)) and slow subthreshold slope (SS), primarily due to limited Schottky barrier height (SBH) between graphene and the channel as well as the gradual SBH changes under V-GS influence. Addressing these challenges, our work introduces a vertical PN heterojunction channel, achieved by stacking p-WSe2 and n-MoSe2 (type II junction) on graphene. This arrangement results in an elevated SBH (0.43 eV) and a notable improvement in ON/OFF ratio (10(5)similar to 10(6)) and SS (0.6 V dec(-1)). Unlike single-channel graphene barristors, the PN heterojunction device demonstrates substantial SBH modulation, effectively crossing the Dirac point within the graphene band to facilitate rapid charge transitions with minor V-GS variations. Setting a new benchmark in TMDs field, our WSe2/MoSe2 heterostack barristor showcases not only improved ON/OFF ratio but also marks a maximum benefit of SS performance through the strategic utilization of graphene's minimal density of state. Furthermore, this device is extended to exhibit a relatively fast dynamic photoresponse (similar to 16 ms) in the visible range, paving the way for high-performance graphene electronics.