Reconfiguring\nvan der Waals Metal–Semiconductor\nContacts via Selenium Intercalation/Deintercalation Post-Treatment

To achieve the commercialization\nof two-dimensional (2D) semiconductors,\nthe identification of an appropriate combination of 2D semiconductors\nand three-dimensional (3D) metals is crucial. Furthermore, understanding\nthe van der Waals (vdW) interactions between these materials in thin-film\nsemiconductor processes is essential. Optimizing these interactions\nrequires precise control over the properties of the vdW interface\nthrough specific pre- or post-treatment methods. This study utilizes\nSe-environment annealing as a post-treatment technique, which allows\nfor modification of the vdW gap distance and enhancement of the stability\nof the interfacial structure through the process of Se intercalation\nand deintercalation at the 2D–3D interface. The depth of Se\nintercalation and deintercalation is adjusted by varying the temperature\nand duration of the postannealing process in an Se environment. This\nprecise control over the process enables the effective metallization\nof 2D semiconductors. The results indicate that expanding the vdW\ngap and stabilizing the interface structure through this post-treatment\nsignificantly improve the metal contact properties in devices such\nas field-effect transistors and photovoltaic Schottky diodes by minimizing\nmetal-induced gap states, thus reducing Fermi level pinning. The application\nof Se intercalation and deintercalation techniques achieves an exceptionally\nlow contact resistance of 773 Ω·μm between p-type\nWSe<sub>2</sub> and Au. Additionally, the integration of doping-free\nWSe<sub>2</sub> complementary metal-oxide-semiconductor (CMOS) circuits\nusing Se-environment annealing and blocking layers is demonstrated,\nestablishing a promising advancement in semiconductor technology.