Atomic Layer Deposition of High-Quality AlO Thin Films on MoS 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 AlO films with thickness down to 1.5 nm on MoS is introduced. By treating the surface using water plasma prior to the ALD process, hydroxyl groups are introduced to the MoS 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 AlO films show excellent device-related electrical performance characteristics, including low interface trap density and outstanding gate controllability.