High-κ Dielectric on ReS(2): In-Situ Thermal Versus Plasma-Enhanced Atomic Layer Deposition of Al(2)O(3)

We report an excellent growth behavior of a high-κ dielectric on ReS(2), a two-dimensional (2D) transition metal dichalcogenide (TMD). The atomic layer deposition (ALD) of an Al(2)O(3) thin film on the UV-Ozone pretreated surface of ReS(2) 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 Al(2)O(3) thin film was deposited via plasma-enhanced atomic layer deposition (PEALD), while pinhole free Al(2)O(3) was achieved using a UV-Ozone pretreatment. The ReS(2) 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-κ dielectric for advanced devices based on 2D materials.