Special Issue "Metal Oxide Thin Film: Synthesis, Characterization and Application"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Thin Films".

Deadline for manuscript submissions: 30 September 2020.

Special Issue Editors

Prof. Dr. habil. Erwan Rauwel
Website
Guest Editor
Estonian University of Life Science, Institute of Technology, Kreutzwaldi 56/1, 51014 Tartu, Estonia
Interests: metal oxide thin film deposition; atomic layer deposition; nanomaterial synthesis; metal nanoparticles; metal oxide nanoparticles; water purification; nanomedicine; photovoltaics; hybrid nanocomposites
Special Issues and Collections in MDPI journals
Dr. Protima Rauwel
Website
Guest Editor
Institute of technology, Estonian University of Life Sciences, Kreutzwaldi 56/1, 51014 Tartu, Estonia
Interests: metal oxide thin film characterization; metal nanoparticles; carbon-based hybrid materials; photovoltaics; scanning transmission electron microscopy; water purification
Special Issues and Collections in MDPI journals

Special Issue Information

Dear colleagues,

The last two decades have seen an intensive improvement in thin film deposition methods, enabling the precise coating of surfaces at the nanoscale. Today, it is possible to coat surfaces with complex compositions and synthesize multilayers, enabling the development of synergistic effects through the mutual interaction of such layers. The deposition of complex structures allows for the development of new technologies, with recent advances in deposition techniques further miniaturizing electronic devices.

The development of these new technologies towards scaling down the size of the produced devices requires accurate control of the deposition process. The latter then allows tailoring thin films and nanodevices to ones desires. The recent advances are not only limited to nanoelectronics but are applicable to every field, viz., anti-corrosion coating, biocidal coating, or photovoltaic devices, in order to cope with the present demands of the society. The last two decades have also witnessed the accelerated development of atomic layer deposition processes that enable the conformal coating at nanoscale now up-scalable to larger surface areas.

This Special Issue will compile recent developments in the field of metal oxide thin film deposition.  The articles presented in this Special Issue will cover various topics, ranging from but not limited to the optimization of deposition methods, thin films preparations, the functionalization of surfaces with targeted applications, nanosensors, catalysis, electronic devices, biocidal coating, and the synthesis of nanostructures via the accurate control of thin film deposition methods, among others. Topics are open to metal oxide thin film deposition and characterization for the development of applications.

Prof. Dr. Erwan Rauwel
Dr. Protima Rauwel
Guest Editors

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. Materials is an international peer-reviewed open access semimonthly 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 2000 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

  • metal oxide thin films
  • metallic thin films
  • atomic layer deposition
  • chemical vapor deposition
  • sputtering
  • spin coating
  • dip-coating
  • multilayers
  • functional thin films
  • photovoltaic cells
  • catalysis
  • transistor technology
  • optoelectronic
  • sensors
  • biocidal coating
  • corrosion

Published Papers (7 papers)

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Research

Open AccessArticle
Phase and Orientation Control of NiTiO3 Thin Films
Materials 2020, 13(1), 112; https://doi.org/10.3390/ma13010112 - 25 Dec 2019
Abstract
Subtle changes in the atomic arrangement of NiTiO3 in the ilmenite structure affects its symmetry and properties. At high temperatures, the cations are randomly distributed throughout the structure, resulting in the corundum structure with R−3c symmetry. Upon cooling, the cations [...] Read more.
Subtle changes in the atomic arrangement of NiTiO3 in the ilmenite structure affects its symmetry and properties. At high temperatures, the cations are randomly distributed throughout the structure, resulting in the corundum structure with R−3c symmetry. Upon cooling, the cations order in alternating layers along the crystallographic c axis, resulting in the ilmenite structure with R−3 symmetry. Related to this is the R3c symmetry, where the cations alternate both perpendicularly and along the c axis. NiTiO3 with the latter structure is highly interesting as it exhibits ferroelectric properties. The close relationship between structure and properties for ilmenite-related structures emphasizes the importance of being able to control the symmetry during synthesis. We show that the orientation and symmetry of thin films of NiTiO3 formed by atomic layer deposition (ALD) can be controlled by choice of substrate. The disordered phase (R−3c), previously only observed at elevated temperatures, have been deposited at 250 °C on α-Al2O3 substrates, while post-deposition annealing at moderate temperatures (650 °C) induces ordering (R−3). We have in addition explored the symmetry and epitaxial orientation obtained when deposited on substrates of LaAlO3(100), SrTiO3(100) and MgO(100). The presented work demonstrates the possibilities of ALD to form metastable phases through choice of substrates. Full article
(This article belongs to the Special Issue Metal Oxide Thin Film: Synthesis, Characterization and Application)
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Open AccessArticle
Atomic Layer Deposition of GdCoO3 and Gd0.9Ca0.1CoO3
Materials 2020, 13(1), 24; https://doi.org/10.3390/ma13010024 - 19 Dec 2019
Abstract
Thin films of the catalytically interesting ternary and quaternary perovskites GdCoO3 and Gd0.9Ca0.1CoO3 are fabricated by atomic layer deposition using metal β-diketonates and ozone as precursors. The resulting thin films are amorphous as deposited and become single-oriented [...] Read more.
Thin films of the catalytically interesting ternary and quaternary perovskites GdCoO3 and Gd0.9Ca0.1CoO3 are fabricated by atomic layer deposition using metal β-diketonates and ozone as precursors. The resulting thin films are amorphous as deposited and become single-oriented crystalline on LaAlO3(100) and YAlO3(100/010) after post-annealing at 650 °C in air. The crystal orientations of the films are tunable by choice and the orientation of the substrate, mitigated through the interface via solid face epitaxy upon annealing. The films exhibit no sign of Co2+. Additionally, high-aspect-ratio Si(100) substrates were used to document the suitability of the developed process for the preparation of coatings on more complex, high-surface-area structures. We believe that coatings of GdCoO3 and Gd1−xCaxCoO3 may find applications within oxidation catalysis. Full article
(This article belongs to the Special Issue Metal Oxide Thin Film: Synthesis, Characterization and Application)
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Open AccessArticle
Improving the Tribological Performance of MAO Coatings by Using a Stable Sol Electrolyte Mixed with Cellulose Additive
Materials 2019, 12(24), 4226; https://doi.org/10.3390/ma12244226 - 16 Dec 2019
Cited by 1
Abstract
In this study, micro-arc oxidation (MAO) of aluminum 6061 alloy was carried out within a silicate base electrolyte containing 0.75 g/L of cellulose, and the tribological properties of the coating were investigated. The as-prepared coating was detected by Fourier Transform Infrared Spectroscopy (FTIR), [...] Read more.
In this study, micro-arc oxidation (MAO) of aluminum 6061 alloy was carried out within a silicate base electrolyte containing 0.75 g/L of cellulose, and the tribological properties of the coating were investigated. The as-prepared coating was detected by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), a scanning electron microscope (SEM) and an energy-dispersive spectrometer (EDS), respectively. The results suggested that cellulose filled in the microcracks and micropores, or it existed by cross-linking with Al3+. In addition, it was found that the cellulose had little effect on the coating hardness. However, the thickness and roughness of the coating were improved with the increase in cellulose concentration. Moreover, the ball-on-disk test showed that the friction coefficient, weight loss and wear rate of the MAO coating decreased with the increase in cellulose concentration. Further, the performances of the coatings obtained in the same electrolyte, under different preserved storage periods, were compared, revealing that the cellulose was uniformly dispersed in the electrolyte and improved the tribological properties of the MAO coating within 30 days. Full article
(This article belongs to the Special Issue Metal Oxide Thin Film: Synthesis, Characterization and Application)
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Open AccessArticle
Influence of Carrier Gases on the Quality of Epitaxial Corundum-Structured α-Ga2O3 Films Grown by Mist Chemical Vapor Deposition Method
Materials 2019, 12(22), 3670; https://doi.org/10.3390/ma12223670 - 07 Nov 2019
Abstract
This report systematically investigates the influence of different carrier gases (O2, N2, and air) on the growth of gallium oxide (Ga2O3) thin films on c-plane sapphire substrates by using the mist-CVD method. Although XRD and [...] Read more.
This report systematically investigates the influence of different carrier gases (O2, N2, and air) on the growth of gallium oxide (Ga2O3) thin films on c-plane sapphire substrates by using the mist-CVD method. Although XRD and Raman measurements show that the pure corundum-structured α-Ga2O3 with single (0006) plane orientation was successfully obtained for all three different carrier gases, the crystal quality could be greatly affected by the carrier gas. When O2 is used as the carrier gas, the smallest full-width at half maximum (FWHM), the very sharp absorption cutoff edge, the perfect lattice structure, the highest growth rate, and the smooth surface can be obtained for the epitaxial α-Ga2O3 film as demonstrated by XRD, UV-VIS, TEM, AFM (Atomic Force Microscope), and SEM measurements. It is proposed that the oxygen content in carrier gas should be responsible for all of these results. XPS (X-ray photoelectron spectroscopy) analysis also confirms that more oxygen elements can be included in epitaxial film when O2 is used as the carrier gas and thus help improve the crystal quality. The proper carrier gas is essential for the high quality α-Ga2O3 growth. Full article
(This article belongs to the Special Issue Metal Oxide Thin Film: Synthesis, Characterization and Application)
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Open AccessArticle
A Novel Self-Adaptive Control Method for Plasma Electrolytic Oxidation Processing of Aluminum Alloys
Materials 2019, 12(17), 2744; https://doi.org/10.3390/ma12172744 - 27 Aug 2019
Abstract
Plasma electrolytic oxidation processing is a novel promising surface modification approach for various materials. However, its large-scale application is still restricted, mainly due to the problem of high energy consumption of the plasma electrolytic oxidation processing. In order to solve this problem, a [...] Read more.
Plasma electrolytic oxidation processing is a novel promising surface modification approach for various materials. However, its large-scale application is still restricted, mainly due to the problem of high energy consumption of the plasma electrolytic oxidation processing. In order to solve this problem, a novel intelligent self-adaptive control technology based on real-time active diagnostics and on the precision adjustment of the process parameters was developed. Both the electrical characteristics of the plasma electrolytic oxidation process and the microstructure of the coating were investigated. During the plasma electrolytic oxidation process, the discharges are maintained in the soft-sparking regime and the coating exhibits a good uniformity and compactness. A total specific energy consumption of 1.8 kW h m−2 μm−1 was achieved by using such self-adaptive plasma electrolytic oxidation processing on pre-anodized 6061 aluminum alloy samples. Full article
(This article belongs to the Special Issue Metal Oxide Thin Film: Synthesis, Characterization and Application)
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Open AccessArticle
Optimizing the Properties of InGaZnOx Thin Film Transistors by Adjusting the Adsorbed Degree of Cs+ Ions
Materials 2019, 12(14), 2300; https://doi.org/10.3390/ma12142300 - 18 Jul 2019
Abstract
To improve the performance of amorphous InGaZnOx (a-IGZO) thin film transistors (TFTs), in this thesis, Cs+ ions adsorbed IGZO (Cs-IGZO) films were prepared through a solution immersion method at low temperature. Under the modification of surface structure and oxygen vacancies concentrations [...] Read more.
To improve the performance of amorphous InGaZnOx (a-IGZO) thin film transistors (TFTs), in this thesis, Cs+ ions adsorbed IGZO (Cs-IGZO) films were prepared through a solution immersion method at low temperature. Under the modification of surface structure and oxygen vacancies concentrations of a-IGZO film, with the effective introduction of Cs+ ions into the surface of a-IGZO films, the transfer properties and stability of a-IGZO TFTs are greatly improved. Different parameters of Cs+ ion concentrations were investigated in our work. When the Cs+ ions concentration reached 2% mol/L, the optimized performance Cs-IGZO TFT was obtained, showing the carrier mobility of 18.7 cm2 V−1 s−1, the OFF current of 0.8 × 10−10 A, and the threshold voltage of 0.2 V, accompanied by the threshold voltage shifts of 1.3 V under positive bias stress for 5000 s. Full article
(This article belongs to the Special Issue Metal Oxide Thin Film: Synthesis, Characterization and Application)
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Open AccessArticle
Discharge Behavior and Dielectric Breakdown of Oxide Films during Single Pulse Anodizing of Aluminum Micro-Electrodes
Materials 2019, 12(14), 2286; https://doi.org/10.3390/ma12142286 - 17 Jul 2019
Cited by 1
Abstract
Micro-arc discharge events and dielectric breakdown of oxide films play an important role in the formation process of plasma electrolytic oxidation coating. Single pulse anodization of micro-electrodes was employed to study the discharge behavior and dielectric breakdown of oxide films deposited on aluminum [...] Read more.
Micro-arc discharge events and dielectric breakdown of oxide films play an important role in the formation process of plasma electrolytic oxidation coating. Single pulse anodization of micro-electrodes was employed to study the discharge behavior and dielectric breakdown of oxide films deposited on aluminum in an alkaline silicate electrolyte. Voltage and current waveforms of applied pulses were measured and surface morphology of micro-electrodes was characterized from images obtained using scanning electron microscope (SEM). A feasible identification method for the critical breakdown voltage of oxide film was introduced. Different current transients of voltage pulses were obtained, depending on applied pulse voltage and duration. In addition, the active capacitive effect and complex non-linear nature of plasma electrolytic oxidation process is confirmed using dynamic electrical characteristic curves. A good correlation between the pulse parameters and shape of discharge channels was observed. Circular opened pores were found to close with increasing potential and pulse width. Finally, the characteristic parameters of a single discharge event were estimated. Full article
(This article belongs to the Special Issue Metal Oxide Thin Film: Synthesis, Characterization and Application)
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