Band structures and transport properties of broken-gap heterostructures: 2D C3N/MX case

Building van der Waals heterostructures (vdWHs) is an effective method to broaden two-dimensional (2D) material applications in multifunctional devices. However, few broken-gap vdWHs are realized, which limit 2D materials development in the tunnel field-effect transistors. Here, based on the density functional theory, we theoretically design the stable 2D C3N/MX(M = Ga, In; X = S, Se, Te) vdWHs, where the band-to-band tunneling (BTBT) exists due to the broken-gap band alignment. The negative electric field expands the tunneling window, while multifunctional band alignment can be realized under positive electric field. Moreover, the I–V curves present the obvious negative differential resistance behavior. This work provides the understanding of physical mechanism and possible applications for 2D broken-gap vdWHs.