Room-Temperature Operation of an Injection-Type Ballistic Rectifier on Bilayer Graphene

This work investigates the performance improvement of a four-probe ballistic rectifier on bilayer graphene (BLG) through the formation of an energy gap under a perpendicular electric field. For this purpose, exfoliated BLG was deposited on oxidized n+-Si and structured into an asymmetric cross junction with 90 nm wide channels. The junction consists of a straight voltage stem (contacts U, L) and slanted current injectors (contacts 1, 2). The differential conductance of the stem, gUL, as a function of back-gate bias, VBG, reveals clear indications of energy gap formation and lateral depletion zones at the edges of the channel. The DC characteristic of the ballistic rectifier, VUL(I12), shows an increase in the output voltage VUL with increasing VBG. We attribute this to reduced diffuse scattering at the rough edges when the lateral depletion zones form smooth barriers.