High-κ Dielectric on ReS₂: In-Situ Thermal Versus Plasma-Enhanced Atomic Layer Deposition of Al₂O₃

• Main Authors: Ava Khosravi, Rafik Addou, Massimo Catalano, Jiyoung Kim, Robert M. Wallace
• Format: Article
• Language: English
• Published: MDPI AG 2019-03-01
• Series: Materials
• Subjects: rhenium sulfide; atomic layer deposition; plasma-enhanced atomic layer deposition; X-ray photoelectron spectroscopy
• Online Access: https://www.mdpi.com/1996-1944/12/7/1056
• ISSN: 1996-1944

We report an excellent growth behavior of a high-κ dielectric on ReS₂, a two-dimensional (2D) transition metal dichalcogenide (TMD). The atomic layer deposition (ALD) of an Al₂O₃ thin film on the UV-Ozone pretreated surface of ReS₂ 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 Al₂O₃ thin film was deposited via plasma-enhanced atomic layer deposition (PEALD), while pinhole free Al₂O₃ was achieved using a UV-Ozone pretreatment. The ReS₂ 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.