(312f) Direct Growth of N-Doped Monolayer and Bilayer WSe2 Via Chemical Vapor Deposition

Transition metal dichalcogenides (TMDs) as one of the most promising semiconducting materials play a key role in the revolution of future two-dimensional (2D) electronics. WSe₂ are considered to be promising candidates to replace conventional silicon-based semiconducting channel in next-generation electronics not only for its excellent optoelectrical properties but also its easier tunability of doping, compared to other TMDs. The doping strategies of WSe₂ have been widely reported in recent years, including substitutional doping, posttreatment (e.g., plasma, chemical functionalization, laser irradiation), but rare of them enables direct growth of n-doped WSe₂. In this work, we reported a dopant- and posttreatment-free doping method by one-pot chemical vapor deposition (CVD), where the doping is controlled by flow gas in the growth. Few-layer WSe₂ grown by CVD, especially monolayer and bilayer WSe₂, usually exhibit p-doped and bipolar properties. By applying this approach, CVD-grown n-type monolayer and bilayer WSe₂ are achieved successfully, which is rare in previously reported literatures. Through changing the gas flow, the doping concentration is controllably tuned. To further investigate the origins of the transition of transport polarity, characterizations of scanning transmission electron microscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy are conducted. The transport performance is verified by electrical measurements based on field effect transistors (FETs) fabricated via van der Waals integration. Furthermore, the n-doped bilayer WSe₂ FET is integrated into complementary metal oxide semiconductor inverters, which realizes low power consumption up to only 40 pW. Our work is expected to reveal a potential way of electronic engineering to construct future two-dimensional electronics.