Functional Thin Films and Coatings: Present Status, Challenges, and a Look Forward

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Thin Films".

Deadline for manuscript submissions: 15 October 2024 | Viewed by 3358

Special Issue Editor


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Guest Editor
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
Interests: fabrication and characterization of high-quality thin-film devices

Special Issue Information

Dear Colleagues,

Functional thin films can achieve specific functions through physical, chemical or biological means, and they have been widely used in electronics, optoelectronics, medicine, environmental protection, and other fields. Therefore, they play an important role in the development of modern science and technology.

Despite the great progress in this field, several significant challenges still remain, such as the exploration of an advanced theoretical mechanism, the fabrication of on-demand designed high-quality thin films, and the precise control of their performance.

This Special Issue will serve as a forum for papers on the following topics:

  • The design and preparation of functional films and/or coatings;
  • The advanced characterization of films or coatings;
  • The preparation and application of functional films and/or coatings;
  • The theoretical calculation of functional films and/or coatings;
  • New mechanisms of novel properties for functional films.

Dr. Yanlong Wang
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at mdpi.longhoe.net 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 submissions that pass pre-check are 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 2600 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.

Keywords

  • functional coatings
  • optical properties
  • thin films
  • spectroscopy
  • advanced characterization

Published Papers (4 papers)

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Research

15 pages, 10572 KiB  
Article
Rate-Dependent Evolution of Microstructure and Stress in Silicon Films Deposited by Electron Beam Evaporation
by Runar Plünnecke Dahl-Hansen, Marit Stange, Tor Olav Sunde and Alexander Ulyashin
Coatings 2024, 14(7), 808; https://doi.org/10.3390/coatings14070808 - 28 Jun 2024
Viewed by 365
Abstract
Growing high-quality Si films at high rates with thicknesses ranging from the few nm- to µm-range while kee** the material consumption at a minimum is important for a wide range of Si-based technologies, spanning from batteries to sensors and solar cells. In this [...] Read more.
Growing high-quality Si films at high rates with thicknesses ranging from the few nm- to µm-range while kee** the material consumption at a minimum is important for a wide range of Si-based technologies, spanning from batteries to sensors and solar cells. In this work, we elucidate the effects of electron beam deposition (e-beam) conditions on the growth of ~4 µm thick Si layers on bare and thermally oxidized (001)-oriented Si substrates. All depositions are performed from a stabilized and refillable melt of broken B-doped wafers and recollected using Si-shields during deposition for recycling. We find that increasing the deposition rate from 0.3 to 23 nm/s at a substrate temperature of 1000 °C reduces the roughness, void fraction, and residual stress of epitaxial Si-on-Si layers. For Si-on-SiO2, all films are polycrystalline under the same deposition conditions as for Si-on-Si, with a reduction in void fraction and increase in roughness at higher deposition rates. The residual stress for Si-on-SiO2 is comparable across all deposition rates >1 nm/s. Furthermore, we measure lower resistivities in the films than in the feedstock for Si-on-Si and higher than the feedstock for Si-on-SiO2. While the films become microstructurally denser and less defective at higher deposition rates, the resistivity increases for each next deposition step in the case of multi-step depositions from the same feedstock. Time-of-flight scanning secondary mass spectroscopy measurements show that the films have a significantly higher B-concentration than the feedstock, suggesting B-gettering to the melted region and transferring to the Si film upon the e-beam deposition process. This work demonstrates how electron beam evaporation can be used to recollect and recycle waste Si pieces, bringing important insights into how the deposition parameters influence the quality of the deposited polycrystalline as well as epitaxial thin-to-thick films. Full article
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20 pages, 5753 KiB  
Article
Wet-Chemical Fabrication of Functional Humidity Sensors on a TiO2-Coated Glass Substrate via UV Photodeposition
by Bozhidar I. Stefanov
Coatings 2024, 14(7), 795; https://doi.org/10.3390/coatings14070795 - 26 Jun 2024
Viewed by 991
Abstract
This work demonstrates a completely wet-chemical procedure for the fabrication of a functional impedimetric humidity-sensing device on a titania (TiO2) surface. Optically transparent anatase TiO2 thin films were deposited on a glass substrate via dip-coating from a titanium tetraisopropoxide (TTIP)–acetylacetonate [...] Read more.
This work demonstrates a completely wet-chemical procedure for the fabrication of a functional impedimetric humidity-sensing device on a titania (TiO2) surface. Optically transparent anatase TiO2 thin films were deposited on a glass substrate via dip-coating from a titanium tetraisopropoxide (TTIP)–acetylacetonate (AA)-based sol and surface-functionalized with a nickel oxide (NiOx) layer by ultraviolet (UV) photodeposition. Photodeposition was employed to form the interdigitated electrode pattern on the TiO2 surface as well through activation with a silver catalyst to promote electroless copper deposition. The relative humidity (RH) response of the pristine TiO2- and NiOx/TiO2-functionalized sensors was studied by impedance (Z) measurements in the 15%–90% RH range. It was found that while NiOx functionalization significantly dampens the RH–Z functional dependence, it improves its overall linearity and may successfully be employed for the purposeful design of titania-based sensing devices. Full article
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20 pages, 5191 KiB  
Article
Preparation of n-Tetradecane Phase Change Microencapsulated Polyurethane Coating and Experiment on Anti-Icing Performance for Wind Turbine Blades
by Yiting Wang, He Shen, Zheng Sun, Yan Li and Fang Feng
Coatings 2024, 14(5), 645; https://doi.org/10.3390/coatings14050645 - 19 May 2024
Viewed by 602
Abstract
Icing is a common physical phenomenon, and the icing of wind turbine blades can significantly affect the performance of wind turbines. Therefore, researching methods to prevent icing is of great significance, and the coating method of anti-icing is an effective way to delay [...] Read more.
Icing is a common physical phenomenon, and the icing of wind turbine blades can significantly affect the performance of wind turbines. Therefore, researching methods to prevent icing is of great significance, and the coating method of anti-icing is an effective way to delay icing, with advantages such as low energy consumption and easy implementation. In this study, using the coating method as the background, tetradecane phase change microcapsules were prepared, with a melting enthalpy of 90.8 J/g and a crystallization enthalpy of 96.3 J/g, exhibiting good coverage and energy storage efficiency. After mixing tetradecane phase change microcapsules (PCMS) with polyurethane coating (PUR) and coating them on wind turbine blades, after a 5 min icing wind tunnel test, the coating could significantly delay the icing on the blade surface, with the highest anti-icing rate reaching 60.41%. This indicates that the coating has a good anti-icing effect and provides basic research data for exploring new anti-icing methods. Full article
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10 pages, 3741 KiB  
Article
High-Rate Epitaxial Growth of Silicon Using Electron Beam Evaporation at High Temperatures
by Marit Stange, Tor Olav Sunde, Runar Dahl-Hansen, Kalpna Rajput, Joachim Seland Graff, Branson D. Belle and Alexander G. Ulyashin
Coatings 2023, 13(12), 2030; https://doi.org/10.3390/coatings13122030 - 30 Nov 2023
Cited by 1 | Viewed by 1022
Abstract
This paper describes the high-rate (~1.5 μm/min) growth of Si films on Si supporting substrates with (100) crystallographic orientation at 600 °C, 800 °C, and 1000 °C in a vacuum environment of ~1 × 10−5 mbar using electron beam (e-beam) evaporation. The [...] Read more.
This paper describes the high-rate (~1.5 μm/min) growth of Si films on Si supporting substrates with (100) crystallographic orientation at 600 °C, 800 °C, and 1000 °C in a vacuum environment of ~1 × 10−5 mbar using electron beam (e-beam) evaporation. The microstructure, crystallinity, and conductivity of such films were investigated. It was established that fully crystalline (Raman spectroscopy, EBSD) and stress-free epi-Si layers with a thickness of approximately 50 µm can be fabricated at 1000 °C, while at 600 °C and 800 °C, some poly-Si inclusions were observed using Raman spectroscopy. Hall effect measurements showed that epi-Si layers deposited at 1000 °C had resistivity, carrier concentration, and mobility comparable to those obtained for c-Si wafers fabricated through ingot growth and wafering using the same solar grade Si feedstock used for the e-beam depositions. The dislocation densities were determined to be ∼2 × 107 cm−2 and ∼5 × 106 cm−2 at 800 and 1000 °C, respectively, using Secco etch. The results highlight the potential of e-beam evaporation as a promising and cost-effective alternative to conventional CVD for the growth of epi-Si layers and, potentially, epi-Si wafers. Some of the remaining technical challenges of this deposition technology are briefly indicated and discussed. Full article
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