Large-scale alkali-assisted growth of monolayer and bilayer WSe<sub>2</sub> with a low defect density.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40113798.
- Also identified by DOI 10.1038/s41467-025-57986-1 and PMC identifier 11926382.
- Licence recorded as CC BY-NC-ND.
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Abstract
The development of p-type WSe<sub>2</sub> transistors has lagged behind n-type MoS<sub>2</sub> because of challenges in growing high-quality, large-area WSe<sub>2</sub> films. This study employs an alkali-assisted CVD (AACVD) method by using KOH to enhance nucleation on sapphire substrates, effectively promoting monolayer growth on c-plane sapphire and enabling controlled bilayer seeding on miscut surfaces with artificial steps. With AACVD, we achieve 2-inch monolayer and centimeter-scale bilayer WSe<sub>2</sub> films with defect densities as low as 1.6 × 10<sup>12 </sup>cm<sup>-2</sup> (monolayer) and 1.8 × 10<sup>12 </sup>cm<sup>-2</sup> (bilayer), comparable to exfoliated WSe<sub>2</sub>. Bilayer WSe<sub>2</sub> transistors exhibit hole/electron mobilities of 119/34 cm²/Vs, while monolayers achieve 105/22 cm²/Vs with suitable metal contacts. Additionally, bilayer WSe<sub>2</sub> demonstrates lower contact resistance for both n-type and p-type transistors, making it highly promising for future high-performance electronic applications.