Healing Donor Defect States in CVD-Grown MoS Field-Effect Transistors Using Oxygen Plasma with a Channel-Protecting Barrier.

Molybdenum disulfide (MoS ), a metal dichalcogenide, is a promising channel material for highly integrated scalable transistors. However, intrinsic donor defect states, such as sulfur vacancies (V ), can degrade the channel properties and lead to undesired n-doping. A method for healing the donor defect states in monolayer MoS is proposed using oxygen plasma, with an aluminum oxide (Al O ) barrier layer that protects the MoS channel from damage by plasma treatment. Successful healing of donor defect states in MoS by oxygen atoms, even in the presence of an Al O barrier layer, is confirmed by X-ray photoelectron spectroscopy, photoluminescence, and Raman spectroscopy. Despite the decrease in 2D sheet carrier concentration (Δn = -3.82×10 cm ), the proposed approach increases the on-current and mobility by 18% and 44% under optimal conditions, respectively. Metal-insulator transition occurs at electron concentrations of 5.7×10 cm and reflects improved channel quality. Finally, the activation energy (E ) reduces at all the gate voltages (V ) owing to a decrease in V , which act as a localized state after the oxygen plasma treatment. This study demonstrates the feasibility of plasma-assisted healing of defects in 2D materials and electrical property enhancement and paves the way for the development of next-generation electronic devices.