Healing Donor Defect States in CVD-Grown MoS 2 Field-Effect Transistors Using Oxygen Plasma with a Channel-Protecting Barrier.

Molybdenum disulfide (MoS 2 ), a metal dichalcogenide, is a promising channel material for highly integrated scalable transistors. However, intrinsic donor defect states, such as sulfur vacancies (V s ), can degrade the channel properties and lead to undesired n-doping. A method for healing the donor defect states in monolayer MoS 2 is proposed using oxygen plasma, with an aluminum oxide (Al 2 O 3 ) barrier layer that protects the MoS 2 channel from damage by plasma treatment. Successful healing of donor defect states in MoS 2 by oxygen atoms, even in the presence of an Al 2 O 3 barrier layer, is confirmed by X-ray photoelectron spectroscopy, photoluminescence, and Raman spectroscopy. Despite the decrease in 2D sheet carrier concentration (Δn 2D = -3.82×10 12 cm -2 ), 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 12 cm -2 and reflects improved channel quality. Finally, the activation energy (E a ) reduces at all the gate voltages (V G ) owing to a decrease in V s , 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.