Atomic Layer Deposition of High-Quality Al 2 O 3 Thin Films on MoS 2 with Water Plasma Treatment

Atomic layer deposition (ALD) of ultrathin dielectric films on two-dimensional (2D) materials for electronic device applications remains one of the key challenges because of the lack of dangling bonds on the 2D material surface. In this work, a new technique to deposit uniform and high-quality Al 2 O 3 films with thickness down to 1.5 nm on MoS 2 is introduced. By treating the surface using water plasma prior to the ALD process, hydroxyl groups are introduced to the MoS 2 surface, facilitating the chemisorption of trimethylaluminum in a conventional water-based ALD system. Raman and X-ray photoelectron spectroscopy measurements show that the water plasma treatment does not induce noticeable material degradation. The deposited Al 2 O 3 films show excellent device-related electrical performance characteristics, including low interface trap density and outstanding gate controllability.