High-performance n-type transistors based on CVD-grown large-domain trilayer WSe2

Atomically thin layered tungsten diselenide (WSe2) has attracted tremendous research attention for its potential applications in next-generation electronics. This article reports the synthesis method of high-quality monolayer to trilayer WSe2 by molten-salt-assisted chemical vapor deposition. With the optimization of different types of molten salts and depths of corundum boat, large trilayer WSe2 films can be grown with domain size up to 80 µm for the first time. A systematic study of the electrical properties of the n-type field-effect transistor has been carried out based on WSe2 with the above three different layer thicknesses. The trilayer WSe2 devices exhibit higher drive current, mobility, on/off ratio, and lower contact resistance than both bilayer and monolayer counterparts. Moreover, short channel transistors using the trilayer WSe2 with a channel length of 230 nm have been fabricated, exhibiting an excellent on/off ratio up to 108 and a high current density of 187 µA/μm. This facile synthesis of high-quality large-area multilayer WSe2 provides a pathway for future high-performance two-dimensional electronic devices.