Two-dimensional van der Waals (vdW) layered materials not only are an intriguing fundamental scientific research platform but also provide various applications to multifunctional quantum devices in the field-effect transistors (FET) thanks to their excellent physical properties. However, a metal-semiconductor (MS) interface with a large Schottky barrier causes serious problems for unleashing their intrinsic potentials toward the advancements in high-performance devices. Here, we show that exfoliated vdW Dirac semimetallic PtTe2 can be an excellent electrode for electrons in MoS2 FETs. High-performance FET characteristics reaching the FET mobility of 85 cm2 V-1 s-1 are observed with a negligibly small Schottky barrier height and large on-off current ratio over 108, which is among the highest performances in reported electrodes for MoS2. Discussions are had on the reason that exfoliated PtTe2 with Dirac states shows highly efficient electrode performances based on the comparisons with various other metal electrodes. The orbital hybrid effect between Dirac-semimetal PtTe2 and MoS2 was evidenced by the relative shift of Raman spectra peaks in the heterojunction, resulting in good ohmic contacts. These findings provide an important route to find high-performance electrodes for layered vdW materials and their related quantum devices.
Keywords: PtTe2; Schottky barrier; defects; field-effect transistor; layered materials; local defect states.