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 characterizations 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 (∼38.2 cm2·V–1·s–1) and ON/OFF ratio (∼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.