Synthesis of V2AlC thin films by thermal annealing of nanoscale elemental multilayered precursors: Incorporation of layered Ar bubbles and impact on microstructure formation

Abstract

Periodically stacked nanoscale V/C/Al multilayered thin film precursors were deposited by magnetron sputtering using elemental targets. Their temperature-dependent phase transformation during subsequent thermal annealing in argon towards V2AlC MAX phase formation was investigated. Compositional and microstructural analyses at the nanoscale revealed undulation growth of the nanolayers and preferential incorporation of Ar atoms into amorphous carbon nanolayers within the as-deposited multilayered precursors. Single-phase and basal-plane-oriented V2AlC films were formed at annealing temperatures above 560 °C. The incorporated Ar atoms migrated and aggregated into high-density nanoscale Ar clusters/bubbles located essentially at grain boundaries after annealing, displaying pronounced layered distribution characteristics especially adjacent to the substrate/film interface. The heterogeneous incorporation of argon atoms or clusters in heterostructured films composed of multicomponent sublayers likely represents a common phenomenon during thin film nucleation and growth, while its impact on the macroscopic properties of films remains to be explored.