Halide-Assisted Synthesis of V-WSe₂

Over the past few years, two-dimensional transition metal dichalcogenides (TMDCs) have garnered substantial attention in the field of two-dimensional materials research, owing to their exceptional physicochemical properties. Notably, V-WSe₂ distinguishes itself by reducing the Schottky barrier at the interface between the material and metal electrodes, thus exhibiting remarkable potential for applications in optoelectronic devices. Our work explores the synthesis of monolayer V-WSe₂ through halide-assisted atmospheric-pressure chemical vapor deposition (APCVD), with an emphasis on the effects of various halide types on the growth mechanism. In addition, we investigate the impact of vanadium (V) content on the performance of WSe₂. Comprehensive optical and structural characterizations of the synthesized material were systematically performed. The findings indicate that incorporating halide salts effectively reduces the volatilization temperature of tungsten trioxide (WO₃), thereby markedly enhancing reaction controllability and material crystallinity. Among the tested halide salts, KCl, NaCl, and KI, KI demonstrated the capability to achieve the lowest growth temperature. Varying the V content in the V-WSe₂ structure significantly influences the optical properties, with higher vanadium concentrations reducing the material's optical bandgap and Raman frequency. This study highlights the critical role of halides and vanadium content in the material growth process, providing valuable insights for the controlled synthesis of two-dimensional TMDC materials and how varying vanadium concentrations also affect the material's performance.