Controlled preparation of tungsten diselenide thin films via chemical vapor deposition

Tungsten diselenide (WSe2), a typical transition metal dichalcogenide material, exhibits a single-layer direct bandgap of 1.65 eV and demonstrates both p-type and n-type bipolar conductivity. These properties align with the requirements of most semiconductor devices on the market and offer significant potential in optics, electronics, and low-power applications. This study systematically investigates the deposition of WSe2 thin films using chemical vapor deposition, achieving high-quality films with large dimensions and controllable layer thickness. The effects of growth temperature, duration, NaCl concentration, and chamber pressure on the nucleation density, nucleation rate, film size, layer number, and morphology were examined. Optimal conditions identified through this analysis led to the production of WSe2 thin films with layers ranging from a single 100 μm layer to multiple layers up to 450 μm. These films were characterized using atomic force microscopy and Raman spectroscopy, providing a foundation for refining the controlled preparation of WSe2 thin films.