Reversible Transition of Semiconducting PtSe₂ and Metallic PtTe₂ for Scalable All-2D Edge-Contacted FETs

Two-dimensional (2D) transition metal dichalcogenide (TMD) layers are highly promising as field-effect transistor (FET) channels in the atomic-scale limit. However, accomplishing this superiority in scaled-up FETs remains challenging due to their van der Waals (vdW) bonding nature with respect to conventional metal electrodes. Herein, we report a scalable approach to fabricate centimeter-scale all-2D FET arrays of platinum diselenide (PtSe₂) with in-plane platinum ditelluride (PtTe₂) edge contacts, mitigating the aforementioned challenges. We realized a reversible transition between semiconducting PtSe₂ and metallic PtTe₂ via a low-temperature anion exchange reaction compatible with the back-end-of-line (BEOL) processes. All-2D PtSe₂ FETs seamlessly edge-contacted with transited metallic PtTe₂ exhibited significant performance improvements compared to those with surface-contacted gold electrodes, e.g., an increase of carrier mobility and on/off ratio by over an order of magnitude, achieving a maximum hole mobility of ∼50.30 cm² V^-1 s^-1 at room temperature. This study opens up new opportunities toward atomically thin 2D-TMD-based circuitries with extraordinary functionalities.