Doping-Free All PtSe2 Transistor via Thickness-Modulated Phase Transition

Achieving a high-quality metal contact on two-dimensional (2D) semiconductors still remains a major challenge due to the strong Fermi level pinning and the absence of an effective doping method. Here, we demonstrate high performance all-PtSe2 field-effect transistors (FETs) completely free from those issues, enabled by the vertical integration of a metallic thick PtSe2 source/drain onto the semiconducting ultrathin PtSe2 channel. Owing to its inherent thickness-dependent semiconductor-to-metal phase transition, the transferred metallic PtSe2 transforms the underlying semiconducting PtSe2 into metal at the junction. Therefore, a fully metallized source/drain and semiconducting channel could be realized within the same PtSe2 platform. The ultrathin PtSe2 FETs with PtSe2 vdW contact exhibits excellent gate tunability, superior mobility, and high ON current accompanied by one order lower contact resistance compared to conventional Ti/Au contact FETs. Our work provides a new device paradigm with a low resistance PtSe2 vdW contact which can overcome a fundamental bottleneck in 2D nanoelectronics.

Automated summary

This study demonstrates high-performance all-PtSe2 FETs by vertically integrating a metallic thick PtSe2 source/drain onto the semiconducting ultrathin PtSe2 channel, successfully overcoming the metal contact issue in 2D semiconductors. The transferred metallic PtSe2 induces a semiconductor-to-metal phase transition in the underlying semiconducting PtSe2, achieving fully metallized source/drain and semiconducting channel within the same platform. The PtSe2 FETs exhibit excellent gate tunability, superior mobility, and low contact resistance, providing a new device paradigm for 2D nanoelectronics.