Highly Efficient Electrode of Dirac Semimetal PtTe2 for MoS2-Based Field Effect Transistors

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.