Transport properties of multilayer NbxMo1−xS2/MoS2 in-plane heterostructure tunnel FETs on hexagonal boron nitride substrate

In-plane heterostructures based on transition metal dichalcogenides are promising for applications in tunnel field-effect transistors (TFETs). However, the transport properties of the in-plane heterostructures have not been fully understood due to the presence of generation current derived from the in-gap state of the heterointerface. For further performance improvement, it is important to identify and suppress the origin of the in-gap states at the heterointerface. In this work, we investigated the transport properties of TFETs based on multilayer NbxMo1−xS2/MoS2 in-plane heterostructures on atomically flat hexagonal boron nitride substrate. We observed a transition from staggered gap to broken gap band alignment by electron doping to MoS2 and that band-to-band tunneling current was dominant below 80 K, a higher temperature compared with the heterostructure on an SiO2 surface. These results indicate that the use of atomically flat substrates helps reduce generation current from strain-derived in-gap states in NbxMo1−xS2/MoS2 in-plane heterostructures.