Atomically thin resonant tunnel diodes built from synthetic van der Waals heterostructures

Vertical integration of two-dimensional van der Waals materials is predicted to lead to novel electronic and optical properties not found in the constituent layers. Here, we present the direct synthesis of two unique, atomically thin, multi-junction heterostructures by combining graphene with the monolayer transition-metal dichalcogenides: molybdenum disulfide (MoS2), molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2). The realization of MoS2–WSe2–graphene and WSe2–MoS2–graphene heterostructures leads to resonant tunnelling in an atomically thin stack with spectrally narrow, room temperature negative differential resistance characteristics. The family of two-dimensional materials is ever growing, but greater functionality can be realized by combining them together. Here, the authors report the direct synthesis of multijunction heterostructures made from graphene, tungsten diselenide and either molybdenum disulphide or molybdenum diselenide.