Improving Contacts\nand Electrical Performances of\nNanofilms of MoS₂ Transistors through Ultrastrong vdW Integration\nwith Dirac Semimetal PtTe₂

Abstract

Semiconductor–metal contacts as one major challenge\nhave\nseverely hindered the further progress of two-dimensional (2D) electronics.\nHere, we present a simple and effective strategy to improve the contacts\nand electrical performances by fabricating van der Waals (vdW) heterostructures\nwith 2D semiconductor MoS₂ and type-II Dirac semimetal\nPtTe₂. The semiconductor MoS₂ and Dirac semimetal\nPtTe₂ nanoflakes are synthesized through CVD routes separately,\nfollowed by systematic material characterizations to confirm their\nstructures. Furthermore, we constructed MoS₂/PtTe₂ vdW heterostructures via a transfer technology with as-grown MoS₂ and PtTe₂ nanoflakes. The field-effect transistor\nbased on MoS₂/PtTe₂ heterostructures shows ohmic\ncontact and improved electrical performances, such as two-terminal\ncarrier mobility (∼38.2 cm²·V^–1·s^–1) and ON/OFF ratio (∼10⁴). We ascribe the improvement of contact and electrical performances\nto the utilization of ultrahigh-conductive layered PtTe₂ as an interlayer. The theoretical calculations demonstrate that\nthe vdW contact can eliminate the Fermi level pinning effect; meanwhile,\nthe ultrastrong covalent-like interlayer coupling guarantees the high-efficiency\ncarrier injection across PtTe₂ and MoS₂. The\nconcept that synergizes 2D semiconductors as the channel and Dirac\nsemimetal PtTe₂ as an interlayer will offer a promising\napproach toward the design of high-performance 2D electronics.