Realizing Stable p-Type Transporting in Two-Dimensional WS₂ Films

Two-dimensional (2D) semiconductors have become promising candidates for nanoelectronics applications due to their unique layered structure and rich physical properties. However, the significant lack of reproducible p-type doping methods that can avoid the instability induced by the widely used charge transfer doping method greatly limits the applications of these semiconductors in complementary metal-oxide-semiconductor (CMOS) integrated digital circuits. This work presents a new scheme to realize stable p-type doping for WS 2 with excellent layer controllability, wafer-level uniformity, and high reproducibility at the same time. The p-type WS 2 was produced by introducing substitutional doping of sulfur with nitrogen atoms during the sulfurization of WO x N y film. Nitrogen atoms acted as acceptors moving the Fermi level of WS 2 toward the valance band. Both experimental and theoretical investigations were designed to study the physical properties of the films fabricated. The WS 2 based field-effect transistors exhibited a well-defined p-type behavior with a large on/off current ratio of ∼10 5 and a high hole mobility of ∼18.8 cm 2 V –1 s –1 . This opens up a promising method to realize stable p-type doping of 2D materials, which is very attractive for future large-scale 2D CMOS device applications.