Direct Formation of Stable 1T′ Molybdenum Telluride (MoTe2) by Laser Annealing Processes as Robust Contacts for High-Performance Molybdenum Disulfide (MoS2) Field Effect Transistors

Abstract

Semimetals, with their low density of states near the Fermi level, effectively suppress metal-induced gap states, enabling near-zero Schottky barrier heights in two-dimensional (2D) field-effect transistors (FETs). However, the low melting point of semimetals (Bi, Sb) limits the applications of 2D FETs at high temperatures. Here, we introduce a robust semimetal contact strategy for high-performance MoS₂ FETs, based on continuous-wave laser annealing of elemental metals (Bi, Mo, Pt, W) and tellurium to form metal tellurides. Specifically, the phase of molybdenum telluride (1T′/2H) can be prepared under different laser parameters. In particular, large-area, high-crystallinity films of stable 1T′-MoTe₂ can be synthesized uniformly, and source/drain electrodes of 1T′-MoTe₂ are formed directly from elemental Mo and Te without damaging the underlying MoS₂. Electrical characterization shows that MoS₂ FETs with 1T′-MoTe₂ contacts match the performance of Bicontacted devices and maintain device uniformity over large areas. Moreover, 1T′-MoTe₂ electrodes sustain excellent on/off ratios of ∼10⁸ after an annealing temperature at 400 °C and ∼10⁵ after 500 °C, whereas Bi contacts fail at 400 °C. This laser annealing approach offers a scalable method to fabricate robust electrodes for 2D transistors, paving the way for high-temperature CMOS applications.