Special Issue "Current Research in Thin Film Deposition: Applications, Theory, Processing, and Characterisation"

A special issue of Coatings (ISSN 2079-6412).

Deadline for manuscript submissions: 31 August 2020.

Special Issue Editor

Dr. Ross Birney
E-Mail Website
Guest Editor
Institute of Thin Films, Surfaces and Imaging, Department of Physics, University of the West of Scotland, Paisley, Scotland PA1 2BE, UK
Interests: gravitational wave detection; thin film coatings; optics, optical coatings; ion beam technology; tribological coatings; biomedical coatings; vacuum deposition; material characterisation

Special Issue Information

Dear Colleagues,

We invite you to submit your work to this Special Issue, dedicated to recent and current research in the field of vacuum-deposited thin film coatings. Today, thin films are near-ubiquitous and are utilised in a very wide range of industrially and scientifically important areas; from familiar everyday instances such as  antireflective coatings on ophthalmic lenses, smartphone optics, photovoltaics, decorative and tool coatings; to somewhat more exotic applications, such as astronomical instrumentation (e.g., ultra-low loss dielectric mirrors and beamsplitters in gravitational wave detectors, such as Laser Interferometer Gravitational-Wave Observatory (LIGO)), gas sensing, medical devices and implants, and accelerator coatings (e.g., coatings for Large Hadron Collider (LHC) and Compact Linear Collider (CLIC) experiments at European Organization for Nuclear Research (CERN)).

The topics of interest for this Special Issue include, but are not limited to:

  • Thin film Deposition techniques and technology, e.g., ion beam sputtering, CVD, e-beam, thermal evaporation, magnetron sputtering, ALD;
  • Vacuum technology;
  • Novel materials for thin film applications, e.g., graphene, stanene, silicene, germanene, nanoparticle coatings, metamaterials;
  • New applications for thin film coatings;
  • Optical coatings, e.g., for UV, visible, IR, X-ray Bragg mirrors, quantum optics;
  • Tribological/barrier/protective coatings, e.g., gas barrier coatings, anticorrosion coatings, antifouling coatings;
  • Characterisation of thin film coatings: Methods, techniques and theory;
  • Reviews of prior research;
  • Biomedical coatings.

Dr. Ross Birney
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (7 papers)

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Research

Open AccessArticle
Combining Thermal Spraying and Magnetron Sputtering for the Development of Ni/Ni-20Cr Thin Film Thermocouples for Plastic Flat Film Extrusion Processes
Coatings 2019, 9(10), 603; https://doi.org/10.3390/coatings9100603 - 24 Sep 2019
Abstract
In the digitalization of production, temperature determination is playing an increasingly important role. Thermal spraying and magnetron sputtering were combined for the development of Ni/Ni-20Cr thin film thermocouples for plastic flat film extrusion processes. On the thermally sprayed insulation layer, AlN and BCN [...] Read more.
In the digitalization of production, temperature determination is playing an increasingly important role. Thermal spraying and magnetron sputtering were combined for the development of Ni/Ni-20Cr thin film thermocouples for plastic flat film extrusion processes. On the thermally sprayed insulation layer, AlN and BCN thin films were deposited and analyzed regarding their structural properties and the interaction between the plastic melt and the surfaces using Ball-on-Disc experiments and High-Pressure Capillary Rheometer. A modular tool, containing the deposited Ni/Ni-20Cr thin film thermocouple, was developed and analyzed in a real flat film extrusion process. When calibrating the thin film thermocouple, an accurate temperature determination of the flowing melt was achieved. Industrial type K sensors were used as reference. In addition, PP foils were produced without affecting the surface quality by using thin film thermocouples. Full article
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Open AccessArticle
Simple Non-Destructive Method of Ultrathin Film Material Properties and Generated Internal Stress Determination Using Microcantilevers Immersed in Air
Coatings 2019, 9(8), 486; https://doi.org/10.3390/coatings9080486 - 01 Aug 2019
Abstract
Recent progress in nanotechnology has enabled to design the advanced functional micro-/nanostructures utilizing the unique properties of ultrathin films. To ensure these structures can reach the expected functionality, it is necessary to know the density, generated internal stress and the material properties of [...] Read more.
Recent progress in nanotechnology has enabled to design the advanced functional micro-/nanostructures utilizing the unique properties of ultrathin films. To ensure these structures can reach the expected functionality, it is necessary to know the density, generated internal stress and the material properties of prepared films. Since these films have thicknesses of several tens of nm, their material properties, including density, significantly deviate from the known bulk values. As such, determination of ultrathin film material properties requires usage of highly sophisticated devices that are often expensive, difficult to operate, and time consuming. Here, we demonstrate the extraordinary capability of a microcantilever commonly used in a conventional atomic force microscope to simultaneously measure multiple material properties and internal stress of ultrathin films. This procedure is based on detecting changes in the static deflection, flexural and torsional resonant frequencies, and the corresponding quality factors of the microcantilever vibrating in air before and after film deposition. In contrast to a microcantilever in vacuum, where the quality factor depends on the combination of multiple different mechanical energy losses, in air the quality factor is dominated just by known air damping, which can be precisely controlled by changing the air pressure. Easily accessible expressions required to calculate the ultrathin film density, the Poisson’s ratio, and the Young’s and shear moduli from measured changes in the microcantilever resonant frequencies, and quality factors are derived. We also show that the impact of uncertainties on determined material properties is only minor. The validity and potential of the present procedure in material testing is demonstrated by (i) extracting the Young’s modulus of atomic-layer-deposited TiO2 films coated on a SU-8 microcantilever from observed changes in frequency response and without requirement of knowing the film density, and (ii) comparing the shear modulus and density of Si3N4 films coated on the silicon microcantilever obtained numerically and by present method. Full article
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Open AccessArticle
Fabrication of a Conjugated Fluoropolymer Film Using One-Step iCVD Process and its Mechanical Durability
Coatings 2019, 9(7), 430; https://doi.org/10.3390/coatings9070430 - 08 Jul 2019
Abstract
Most superhydrophobic surface fabrication techniques involve precise manufacturing process. We suggest initiated chemical vapor deposition (iCVD) as a novel CVD method to fabricate sufficiently durable superhydrophobic coating layers. The proposed method proceeds with the coating process at mild temperature (40 °C) with no [...] Read more.
Most superhydrophobic surface fabrication techniques involve precise manufacturing process. We suggest initiated chemical vapor deposition (iCVD) as a novel CVD method to fabricate sufficiently durable superhydrophobic coating layers. The proposed method proceeds with the coating process at mild temperature (40 °C) with no need of pretreatment of the substrate surface; the pressure and temperature are optimized as process parameters. To obtain a durable superhydrophobic film, two polymeric layers are conjugated in a sequential deposition process. Specifically, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (V4D4) monomer is introduced to form an organosilicon layer (pV4D4) followed by fluoropolymer formation by introducing 1H, 1H, 2H, 2H-Perfluorodecyl methacrylate (PFDMA). There is a high probability of covalent bond formation at the interface between the two layers. Accordingly, the mechanical durability of the conjugated fluoropolymer film (pV4D4-PFDMA) is reinforced because of cross-linking. The superhydrophobic coating on soft substrates, such as tissue paper and cotton fabric, was successfully demonstrated, and its durability was assessed against the mechanical stress such as tensile loading and abrasion. The results from both tests confirm the improvement of mechanical durability of the obtained film. Full article
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Open AccessArticle
Structure and Conductivity Studies of Scandia and Alumina Doped Zirconia Thin Films
Coatings 2019, 9(5), 317; https://doi.org/10.3390/coatings9050317 - 12 May 2019
Abstract
In this work, scandia-doped zirconia (ScSZ) and scandia–alumina co-doped zirconia (ScSZAl) thin films were prepared by electron beam vapor deposition. X-ray diffraction (XRD) results indicated a presence of ZrO2 cubic phase structure, yet Raman analysis revealed the existence of secondary tetragonal and [...] Read more.
In this work, scandia-doped zirconia (ScSZ) and scandia–alumina co-doped zirconia (ScSZAl) thin films were prepared by electron beam vapor deposition. X-ray diffraction (XRD) results indicated a presence of ZrO2 cubic phase structure, yet Raman analysis revealed the existence of secondary tetragonal and rhombohedral phases. Thus, XRD measurements were supported by Raman spectroscopy in order to comprehensively analyze the structure of formed ScSZ and ScSZAl thin films. It was also found that Al dopant slows down the formation of the cubic phase. The impedance measurements affirmed the correlation of the amount of secondary phases with the conductivity results and nonlinear crystallite size dependence. Full article
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Open AccessArticle
Study on β-Ga2O3 Films Grown with Various VI/III Ratios by MOCVD
Coatings 2019, 9(5), 281; https://doi.org/10.3390/coatings9050281 - 26 Apr 2019
Abstract
β-Ga2O3 films were grown on sapphire (0001) substrates with various O/Ga (VI/III) ratios by metal organic chemical vapor deposition. The effects of VI/III ratio on growth rate, structural, morphological, and Raman properties of the films were systematically studied. By varying [...] Read more.
β-Ga2O3 films were grown on sapphire (0001) substrates with various O/Ga (VI/III) ratios by metal organic chemical vapor deposition. The effects of VI/III ratio on growth rate, structural, morphological, and Raman properties of the films were systematically studied. By varying the VI/III ratio, the crystalline quality obviously changed. By decreasing the VI/III ratio from 66.9 × 103 to 11.2 × 103, the crystalline quality improved gradually, which was attributed to low nuclei density in the initial stage. However, crystalline quality degraded with further decrease of the VI/III ratio, which was attributed to excessive nucleation rate. Full article
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Open AccessArticle
Aluminum Coated Micro Glass Spheres to Increase the Infrared Reflectance
Coatings 2019, 9(3), 187; https://doi.org/10.3390/coatings9030187 - 12 Mar 2019
Abstract
The reflective properties of micro glass spheres (MGS) such as Solid Micro Glass Spheres (SMGS, “glass beads”) and Micro Hollow Glass Spheres (MHGS, “glass bubbles”) are utilized in various applications, for example, as retro-reflector for traffic road stripe paints or facade paints. The [...] Read more.
The reflective properties of micro glass spheres (MGS) such as Solid Micro Glass Spheres (SMGS, “glass beads”) and Micro Hollow Glass Spheres (MHGS, “glass bubbles”) are utilized in various applications, for example, as retro-reflector for traffic road stripe paints or facade paints. The reflection behavior of the spheres can be further adapted by coating the surfaces of the spheres, e.g., by titanium dioxide or a metallic coating. Such coated spheres can be employed as, e.g., mid infrared (MIR)-reflective additives in wall paints to increase the thermal comfort in rooms. As a result, the demand of heating energy can be reduced. In this paper, the increase of the MIR-reflectance by applying an aluminum coating on MGS is discussed. Aluminum coatings are normally produced via the well-known Physical Vapor Deposition (PVD) or Chemical Vapor Deposition (CVD). In our work, the Liquid Phase Deposition (LPD) method, as a new, non-vacuum method for aluminum coating on spherical spheres, is investigated as an alternative, scalable, and simple coating process. The LPD-coating is characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and reflection measurements. The results are compared to a reference PVD-coating. It is shown that both sphere types, SMGS and MHGS, can be homogeneously coated with metallic aluminum using the LPD method but the surface morphology plays an important role concerning the reflection properties. With the SMGS, a smooth surface morphology and a reflectance increase to a value of 30% can be obtained. Due to a structured surface morphology, a reflection of only 5% could be achieved with the MHGS. However, post-treatments showed that a further increase is possible. Full article
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Open AccessArticle
In Situ Plasma Monitoring of PECVD nc-Si:H Films and the Influence of Dilution Ratio on Structural Evolution
Coatings 2018, 8(7), 238; https://doi.org/10.3390/coatings8070238 - 06 Jul 2018
Cited by 3
Abstract
We report plasma-enhanced chemical vapor deposition (PECVD) hydrogenated nano-crystalline silicon (nc-Si:H) thin films. In particular, the effect of hydrogen dilution ratio (R = H2/SiH4) on structural and optical evolutions of the deposited nc-Si:H films were systematically investigated including [...] Read more.
We report plasma-enhanced chemical vapor deposition (PECVD) hydrogenated nano-crystalline silicon (nc-Si:H) thin films. In particular, the effect of hydrogen dilution ratio (R = H2/SiH4) on structural and optical evolutions of the deposited nc-Si:H films were systematically investigated including Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR) and low angle X-ray diffraction spectroscopy (XRD). Measurement results revealed that the nc-Si:H structural evolution, primarily the transition of nano-crystallization from the amorphous state to the nanocrystalline state, can be carefully induced by the adjustment of hydrogen dilution ratio (R). In addition, an in situ plasma diagnostic tool of optical emission spectroscopy (OES) was used to further characterize the crystallization rate index (Hα*/SiH*) that increases when hydrogen dilution ratio (R) rises, whereas the deposition rate decreases. Another in situ plasma diagnostic tool of quadruple mass spectrometry (QMS) also confirmed that the “optimal” range of hydrogen dilution ratio (R = 30–40) can yield nano-crystalline silicon (n-Si:H) growth due to the depletion of higher silane radicals. A good correlation between the plasma characteristics by in situ OES/QMS and the film characteristics by XRD, Raman and FTIR, for the transition of a-Si:H to nc-Si:H film from the hydrogen dilution ratio, was obtained. Full article
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