High-Quality HfO2 High-K Gate Dielectrics Deposited on Highly Oriented Pyrolytic Graphite via Enhanced Precursor Atomic Layer Seeding

Abstract

In this study, an enhanced precursor atomic layer seeding (EPALS) assisted atomic layer deposition (ALD) is proposed to prepare high-quality hafnium oxide (HfO₂) high-K gate dielectrics on highly oriented pyrolytic graphite (HOPG) surfaces. The EPALS technique addresses the challenge of depositing high-quality oxides directly on two-dimensional (2D) materials, which typically lack dangling bonds on their surfaces. By enhancing the precursor reactivity through remote plasma, the EPALS process facilitates the adsorption of precursors, thereby enabling the effective deposition of HfO₂ on the HOPG surface without compromising its intrinsic sp² structure. The HfO₂ thin films prepared by the EPALS-assisted ALD method upon HOPG present desirable dielectric properties, characterized by a high dielectric constant of 19.65 and a low equivalent oxide thickness of 1.46 nm, as evidenced by the electrical characterization of a metal–insulator–metal structure. Furthermore, Raman and X-ray photoelectron spectroscopy analyses confirm the minimal impact of the EPALS process on the integrity of the HOPG surface. This study provides valuable insights into oxide deposition on 2D materials, paving the way for the advancement of high-performance electronic and optical devices based on graphene and other 2D materials.