title: Parameter Space of Atomic Layer Deposition of Ultrathin Oxides on Graphene.
abstract: Atomic layer deposition (ALD) of ultrathin aluminum oxide (AlOx) films was systematically studied on supported chemical vapor deposition (CVD) graphene. We show that by extending the precursor residence time, using either a multiple-pulse sequence or a soaking period, ultrathin continuous AlOxfilms can be achieved directly on graphene using standard H2O and trimethylaluminum (TMA) precursors even at a high deposition temperature of 200 °C, without the use of surfactants or other additional graphene surface modifications. To obtain conformal nucleation, a precursor residence time of >2s is needed, which is not prohibitively long but sufficient to account for the slow adsorption kinetics of the graphene surface. In contrast, a shorter residence time results in heterogeneous nucleation that is preferential to defect/selective sites on the graphene. These findings demonstrate that careful control of the ALD parameter space is imperative in governing the nucleation behavior of AlOxon CVD graphene. We consider our results to have model system character for rational two-dimensional (2D)/non-2D material process integration, relevant also to the interfacing and device integration of the many other emerging 2D materials.
authors.affiliation: Division of Electrical Engineering, Department of Engineering, University of Cambridge , Cambridge CB3 0FA, United Kingdom.
authors.forename: Adrianus I
authors.initials: AI
authors.lastname: Aria
authors.affiliation: Division of Electrical Engineering, Department of Engineering, University of Cambridge , Cambridge CB3 0FA, United Kingdom.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Nakanishi
authors.affiliation: Division of Electrical Engineering, Department of Engineering, University of Cambridge , Cambridge CB3 0FA, United Kingdom.
authors.forename: Long
authors.initials: L
authors.lastname: Xiao
authors.affiliation: Division of Electrical Engineering, Department of Engineering, University of Cambridge , Cambridge CB3 0FA, United Kingdom.
authors.forename: Philipp
authors.initials: P
authors.lastname: Braeuninger-Weimer
authors.affiliation: Division of Electrical Engineering, Department of Engineering, University of Cambridge , Cambridge CB3 0FA, United Kingdom.
authors.forename: Abhay A
authors.initials: AA
authors.lastname: Sagade
authors.affiliation: Division of Electrical Engineering, Department of Engineering, University of Cambridge , Cambridge CB3 0FA, United Kingdom.
authors.forename: Jack A
authors.initials: JA
authors.lastname: Alexander-Webber
authors.affiliation: Division of Electrical Engineering, Department of Engineering, University of Cambridge , Cambridge CB3 0FA, United Kingdom.
authors.forename: Stephan
authors.initials: S
authors.lastname: Hofmann
keywords: aluminum oxide; atomic layer deposition; conformal deposition; graphene; ultrathin films