title: Morphological and Chemical Evolution of Gradually Deposited Diamond-Like Carbon Films on Polyethylene Terephthalate: From Subplantation Processes to Structural Reorganization by Intrinsic Stress Release Phenomena.
abstract: Diamond-like carbon (DLC) films on polyethylene terephthalate (PET) are nowadays intensively studied composites due to their excellent gas barrier properties and biocompatibility. Despite their applicative features being highly explored, the interface properties and structural film evolution of DLC coatings on PET during deposition processes are still sparsely investigated. In this study two different types of DLC films were gradually deposited on PET by radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) using acetylene plasma. The surface morphology of the deposited samples has been analyzed by atomic force microscopy (AFM). Their chemical composition was investigated by diffusive reflectance infrared Fourier transform (DRIFT) and Raman spectroscopy analysis and the surface wettability by contact angle measurements. Subplantation processes and interface effects are revealed through the morphological and chemical analysis of both types. During plasma deposition processes the increasing carbon load causes the rise of intrinsic film stress. It is proven that stress release phenomena cause the transition between polymer-like to a more cross-linked DLC network by folding dehydrogenated chains into closed 6-fold rings. These findings significantly lead to an enhanced understanding in DLC film growth mechanism by RF-PECVD processes.
authors.affiliation: Department of Physics, University Koblenz-Landau , 56070 Koblenz, Germany.
authors.forename: Alberto
authors.initials: A
authors.lastname: Catena
authors.affiliation: Department of Physics, The Ohio State University , Columbus, Ohio 43210, United States.
authors.forename: Qiaochu
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Department of Chemistry, University Koblenz-Landau , 56070 Koblenz, Germany.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Kunze
authors.affiliation: Department of Physics and Chemistry, University of Palermo , 90100 Palermo, Italy.
authors.forename: Simonpietro
authors.initials: S
authors.lastname: Agnello
authors.affiliation: Department of Physics and Chemistry, University of Palermo , 90100 Palermo, Italy.
authors.forename: Franco M
authors.initials: FM
authors.lastname: Gelardi
authors.affiliation: Department of Physics, University Koblenz-Landau , 56070 Koblenz, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wehner
authors.affiliation: Department of Physics, University Koblenz-Landau , 56070 Koblenz, Germany.
authors.forename: Christian B
authors.initials: CB
authors.lastname: Fischer
keywords: DRIFT; RF-PECVD; Raman; amorphous hydrogenated carbon (a-C:H); film dehydrogenation; grain analysis; interlayer formation