Improving Contacts and Electrical Performances of Nanofilms of MoS2 Transistors through Ultrastrong vdW Integration with Dirac Semimetal PtTe2

Semiconductor-metal contacts as one major challenge have severely hindered the further progress of two-dimensional (2D) electronics. Here, we present a simple and effective strategy to improve the contacts and electrical performances by fabricating van der Waals (vdW) heterostructures with 2D semiconductor MoS2 and type-II Dirac semimetal PtTe2. The semiconductor MoS2 and Dirac semimetal PtTe2 nanoflakes are synthesized through CVD routes separately, followed by systematic material character-izations to confirm their structures. Furthermore, we constructed MoS2/ PtTe2 vdW heterostructures via a transfer technology with as-grown MoS2 and PtTe2 nanoflakes. The field-effect transistor based on MoS2/PtTe2 heterostructures shows ohmic contact and improved electrical performances, such as two-terminal carrier mobility (similar to 38.2 cm2 center dot V-1 center dot s-1) and ON/OFF ratio (similar to 104). We ascribe the improvement of contact and electrical performances to the utilization of ultrahigh-conductive layered PtTe2 as an interlayer. The theoretical calculations demonstrate that the vdW contact can eliminate the Fermi level pinning effect; meanwhile, the ultrastrong covalent-like interlayer coupling guarantees the high-efficiency carrier injection across PtTe2 and MoS2. The concept that synergizes 2D semiconductors as the channel and Dirac semimetal PtTe2 as an interlayer will offer a promising approach toward the design of high-performance 2D electronics.