Direct Growth of Wafer-Scale 2D Semiconductor Transistors via One-Step PtTe₂/2H-MoTe₂ Heterophase Formation

2D semiconductors offer a promising platform for next-generation integrated circuits and large-scale electronic systems. Realizing high-performance p-type transistors, however, remains challenging due to Fermi-level pinning, high contact resistance, and poorly defined interfaces in conventional stepwise fabrication. Here, we demonstrate a single-step tellurization growth strategy that simultaneously forms PtTe₂ contacts on 2H-MoTe₂ channels to directly realize 2D semiconductor transistors. This approach forms PtTe₂/2H-MoTe₂ metal/semiconductor arrays with precise control of the MoTe₂ phase at the PtTe₂ electrode interface, while providing integrated van der Waals metallic contacts without the need for post-growth of metal contacts. Using this method, we achieve wafer-scale heterophase arrays characterized by uniform patterning and well-controlled 2H/1T' phase transformation dynamics. The heterojunctions display sharp and clean interfaces, as verified by TEM, STEM, and EDS mapping. Transistor arrays fabricated from these heterophase structures show Ohmic contacts with low Schottky barrier heights, delivering on/off ratios up to 5 × 10⁴ and consistent mobility of 5-9 cm²/Vs across 100 devices, ensuring efficient carrier injection. Our results establish a scalable pathway for the direct growth of 2D semiconductor transistors, overcoming conventional multi-step device fabrication bottlenecks and providing a promising platform for large-scale, and reproducible 2D electronics.