High-? dielectric on ReS2: In-situ thermal versus plasma-enhanced atomic layer deposition of Al2O3

We report an excellent growth behavior of a high-? dielectric on ReS, a two-dimensional (2D) transition metal dichalcogenide (TMD). The atomic layer deposition (ALD) of an AlO thin film on the UV-Ozone pretreated surface of ReS yields a pinhole free and conformal growth. In-situ half-cycle X-ray photoelectron spectroscopy (XPS) was used to monitor the interfacial chemistry and ex-situ atomic force microscopy (AFM) was used to evaluate the surface morphology. A significant enhancement in the uniformity of the AlO thin film was deposited via plasma-enhanced atomic layer deposition (PEALD), while pinhole free AlO was achieved using a UV-Ozone pretreatment. The ReS substrate stays intact during all different experiments and processes without any formation of the Re oxide. This work demonstrates that a combination of the ALD process and the formation of weak S-O bonds presents an effective route for a uniform and conformal high-? dielectric for advanced devices based on 2D materials.