Reconfiguring van der Waals Metal–Semiconductor Contacts via Selenium Intercalation/Deintercalation Post-Treatment

To achieve the commercialization of two-dimensional (2D) semiconductors, the identification of an appropriate combination of 2D semiconductors and three-dimensional (3D) metals is crucial. Furthermore, understanding the van der Waals (vdW) interactions between these materials in thin-film semiconductor processes is essential. Optimizing these interactions requires precise control over the properties of the vdW interface through specific pre- or post-treatment methods. This study utilizes Se-environment annealing as a post-treatment technique, which allows for modification of the vdW gap distance and enhancement of the stability of the interfacial structure through the process of Se intercalation and deintercalation at the 2D-3D interface. The depth of Se intercalation and deintercalation is adjusted by varying the temperature and duration of the postannealing process in an Se environment. This precise control over the process enables the effective metallization of 2D semiconductors. The results indicate that expanding the vdW gap and stabilizing the interface structure through this post-treatment significantly improve the metal contact properties in devices such as field-effect transistors and photovoltaic Schottky diodes by minimizing metal-induced gap states, thus reducing Fermi level pinning. The application of Se intercalation and deintercalation techniques achieves an exceptionally low contact resistance of 773 Ω·μm between p-type WSe₂ and Au. Additionally, the integration of doping-free WSe₂ complementary metal-oxide-semiconductor (CMOS) circuits using Se-environment annealing and blocking layers is demonstrated, establishing a promising advancement in semiconductor technology.