Functional Oxide Based Thin-Film Materials (Volume II)

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Inorganic Crystalline Materials".

Deadline for manuscript submissions: closed (28 February 2021) | Viewed by 19979

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Guest Editor
Department of Materials Science and Engineering, National Chung Hsing University, 145 Xingda Road, Taichung 40227, Taiwan
Interests: functional thin-film coatings; plasma process; sputtering; chemical vapor deposition; pulsed laser deposition
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Dear Colleagues,

Functional-oxide-based thin-film materials and nanostructures are extraordinary multifunctional crystals with a huge range of emerging application domains, such as sensors, displays, light emitters, photovoltaics, nanotechnology, spintronics, piezoelectric motors, biotechnology, capacitors, transparent electronics, and next-generation memories.

The functional oxide crystal has several favorable properties, including good transparency, high conductivity, wide bandgap, and strong luminescence. Thin-film oxide materials have been grown on various substrates using methods such as hydrothermal, sol–gel, chemical bath, sputtering, plasma CVD, MOCVD, PLD, HVPE, MBE, etc. A number of breakthroughs over the past few years have driven exponential energy into research activity in this field.

We invite investigators to submit papers which discuss the development of functional-oxide-based thin-film materials, including thin-film, nanostructured, and multilayered forms. Mixing oxide-based alloys with other materials could allow for the possible fabrication of advanced devices. Furthermore, the diluted magnetic crystals and combination with two-dimensional materials are welcomed.

The potential topics include but again are not limited to:

  • Growth of functional-oxide-based thin films or nanostructures, including the modeling of crystal growth or reaction mechanisms;
  • Property characterization (optic, electric, piezoelectric, ferromagnetic properties, etc.) and their relationships to external conditions, such as electric field, photo pumping, current injection, gas environment, stress, temperature, etc.;
  • Advances in device development based on finctional oxide materials using thin films or nanostructures;
  • Microstructure analysis and micro–macro correlation of the observed properties and their modeling.

Prof. Dr. Dong-Sing Wuu
Guest Editor

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Keywords

  • Functional oxide-based compounds
  • Growth of oxide thin films or nanostructures
  • Oxide material characterization
  • Oxide-based device fabrication and applications

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Published Papers (7 papers)

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Research

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7 pages, 2041 KiB  
Article
A Comparison Study on Multilayered Barrier Oxide Structure in Charge Trap Flash for Synaptic Operation
by Minkyung Kim, Eunpyo Park, In Soo Kim, Jongkil Park, Jaewook Kim, YeonJoo Jeong, Suyoun Lee, Inho Kim, Jong-Keuk Park, Tae-Yeon Seong and Joon Young Kwak
Crystals 2021, 11(1), 70; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11010070 - 16 Jan 2021
Cited by 5 | Viewed by 2262
Abstract
A synaptic device that contains weight information between two neurons is one of the essential components in a neuromorphic system, which needs highly linear and symmetric characteristics of weight update. In this study, a charge trap flash (CTF) memory device with a multilayered [...] Read more.
A synaptic device that contains weight information between two neurons is one of the essential components in a neuromorphic system, which needs highly linear and symmetric characteristics of weight update. In this study, a charge trap flash (CTF) memory device with a multilayered high-κ barrier oxide structure on the MoS2 channel is proposed. The fabricated device was oxide-engineered on the barrier oxide layers to achieve improved synaptic functions. A comparison study between two fabricated devices with different barrier oxide materials (Al2O3 and SiO2) suggests that a high-κ barrier oxide structure improves the synaptic operations by demonstrating the increased on/off ratio and symmetry of synaptic weight updates due to a better coupling ratio. Lastly, the fabricated device has demonstrated reliable potentiation and depression behaviors and spike-timing-dependent plasticity (STDP) for use in a spiking neural network (SNN) neuromorphic system. Full article
(This article belongs to the Special Issue Functional Oxide Based Thin-Film Materials (Volume II))
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16 pages, 10794 KiB  
Article
Structure and Surface Morphology Effect on the Cytotoxicity of [Al2O3/ZnO]n/316L SS Nanolaminates Growth by Atomic Layer Deposition (ALD)
by D. Osorio, J. Lopez, H. Tiznado, Mario H. Farias, M. A. Hernandez-Landaverde, M. Ramirez-Cardona, J. M. Yañez-Limon, J. O. Gutierrez, J. C. Caicedo and G. Zambrano
Crystals 2020, 10(7), 620; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10070620 - 16 Jul 2020
Cited by 5 | Viewed by 2670
Abstract
Recently, different biomedical applications of aluminum oxide (Al2O3) and zinc oxide (ZnO) have been studied, and they have displayed good biocompatible behavior. For this reason, this study explores nanolaminates of [Al2O3/ZnO]n obtained by atomic [...] Read more.
Recently, different biomedical applications of aluminum oxide (Al2O3) and zinc oxide (ZnO) have been studied, and they have displayed good biocompatible behavior. For this reason, this study explores nanolaminates of [Al2O3/ZnO]n obtained by atomic layer deposition (ALD) on silicon (100) and 316L stainless steel substrates with different bilayer periods: n = 1, 2, 5, and 10. The intention is to correlate the structure, chemical bonds, morphology, and electrochemical properties of ZnO and Al2O3 single layers and [Al2O3/ZnO]n nanolaminates with their cytotoxic and biocompatibility behavior, to establish their viability for biomedical applications in implants based on the 316L SS substrate. These nanolaminates have been characterized by grazing incident X-ray diffraction (XRD), finding diffraction planes for wurtzite type structure from zincite. The chemical bonding and composition for both single layers were identified through X-ray photoelectron spectroscopy (XPS). The morphology and roughness were tested with atomic force microscopy (AFM), which showed a reduction in roughness and grain size with a bilayer period increase. The thickness of the samples was measured with scanning electron microscopy, and the results confirmed the value of ~210 nm for the nanolaminate samples. The electrochemical impedance spectroscopy analysis with Hank’s balanced salt solution (HBSS) evidenced an evolution of [Al2O3/ZnO]n/316L system corrosion resistance of around 95% in relation with the uncoated steel substrate as function of the increase in the bilayers number. To identify the biocompatibility behavior of these nanolaminate systems, the lactate dehydrogenase test was performed with Chinese hamster ovary (CHO) cells for a short system of life cell evaluation. This test shows the cytotoxicity of the multilayer compared to the single layers of Al2O3, ZnO, and 316L stainless steel. The lowest cytotoxicity was found in the single layers of ZnO, which leads to cell proliferation easier than Al2O3, obtaining better adhesion and anchoring to its surface. Full article
(This article belongs to the Special Issue Functional Oxide Based Thin-Film Materials (Volume II))
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11 pages, 4313 KiB  
Article
Synthesis of a Novel In2O3-InN Bottle Nanotube Using In-Situ Partial Oxidation with Enhanced Gas Sensing Platform to Detect NO2
by Qiuyang Ning, Guoguang Wu, Yihui Wang, Yuanbo Sun and Wei Feng
Crystals 2020, 10(7), 570; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10070570 - 02 Jul 2020
Cited by 9 | Viewed by 2058
Abstract
A brand-new gas sensor nanocomposite, In2O3-InN, was synthesized by in-situ partial oxidation of InN and presented fast response–recovery property for NO2 detecting. The structure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy [...] Read more.
A brand-new gas sensor nanocomposite, In2O3-InN, was synthesized by in-situ partial oxidation of InN and presented fast response–recovery property for NO2 detecting. The structure and morphology of the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray detection (EDX) analysis. The results show that the final In2O3-InN composites were composed of hexagonal type In2O3 and hexagonal type InN, which exhibited bottle nanotube structure on the relative macroscopic level. Microscopically, at the interface of In2O3 and InN, n–n hetero junction formed. Works form gas sensing property found that it is obviously that In2O3-InN got a quite stronger response, 1021, at relatively lower temperature, 100 °C, comparing to pure In2O3, 279.1 at 150 °C. After doping, the gas-sensing performance was improved. By analyzing the concentration of oxygen vacation and n–n hetero junctions mechanism, it was verified that the superiority of gas sensing properties of the In2O3-InN can be attributed to the high concentration of oxygen vacancies and the formation of n–n hetero junctions. Full article
(This article belongs to the Special Issue Functional Oxide Based Thin-Film Materials (Volume II))
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10 pages, 1903 KiB  
Article
Effects of Experimental Configuration on the Morphology of Two-Dimensional ZnO Nanostructures Synthesized by Thermal Chemical-Vapor Deposition
by Seok Cheol Choi, Do Kyung Lee and Sang Ho Sohn
Crystals 2020, 10(6), 517; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10060517 - 17 Jun 2020
Cited by 12 | Viewed by 1980
Abstract
Using two experimental configurations, self-assembled zinc oxide (ZnO) nanostructures including nanoplates, nanosaws, and nanobelts were synthesized by thermal chemical-vapor deposition (CVD), and their morphological properties were investigated. ZnO nanostructures grown on Au-coated Si substrates in a parallel setup revealed highly defined ZnO nanoplates [...] Read more.
Using two experimental configurations, self-assembled zinc oxide (ZnO) nanostructures including nanoplates, nanosaws, and nanobelts were synthesized by thermal chemical-vapor deposition (CVD), and their morphological properties were investigated. ZnO nanostructures grown on Au-coated Si substrates in a parallel setup revealed highly defined ZnO nanoplates and branched nanowires. ZnO nanostructures grown in a perpendicular setup using Si substrates with and without the Au catalyst exhibited vertically oriented ZnO nanosaws and randomly aligned nanobelts, respectively. In the thermal CVD method, experiment conditions such as oxygen-flow rate, growth temperature, and catalyst, and experimental configurations (i.e., parallel and perpendicular setups) were important parameters to control the morphologies of two-dimensional ZnO nanostructures showing platelike, sawlike, and beltlike shapes. Full article
(This article belongs to the Special Issue Functional Oxide Based Thin-Film Materials (Volume II))
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15 pages, 5980 KiB  
Article
Initial Growth and Crystallization Onset of Plasma Enhanced-Atomic Layer Deposited ZnO
by Alberto Perrotta, Julian Pilz, Roland Resel, Oliver Werzer and Anna Maria Coclite
Crystals 2020, 10(4), 291; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10040291 - 10 Apr 2020
Cited by 7 | Viewed by 3633
Abstract
Direct plasma enhanced-atomic layer deposition (PE-ALD) is adopted for the growth of ZnO on c-Si with native oxide at room temperature. The initial stages of growth both in terms of thickness evolution and crystallization onset are followed ex-situ by a combination of [...] Read more.
Direct plasma enhanced-atomic layer deposition (PE-ALD) is adopted for the growth of ZnO on c-Si with native oxide at room temperature. The initial stages of growth both in terms of thickness evolution and crystallization onset are followed ex-situ by a combination of spectroscopic ellipsometry and X-ray based techniques (diffraction, reflectivity, and fluorescence). Differently from the growth mode usually reported for thermal ALD ZnO (i.e., substrate-inhibited island growth), the effect of plasma surface activation resulted in a substrate-enhanced island growth. A transient region of accelerated island formation was found within the first 2 nm of deposition, resulting in the growth of amorphous ZnO as witnessed with grazing incidence X-ray diffraction. After the islands coalesced and a continuous layer formed, the first crystallites were found to grow, starting the layer-by-layer growth mode. High-temperature ALD ZnO layers were also investigated in terms of crystallization onset, showing that layers are amorphous up to a thickness of 3 nm, irrespective of the deposition temperature and growth orientation. Full article
(This article belongs to the Special Issue Functional Oxide Based Thin-Film Materials (Volume II))
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12 pages, 3520 KiB  
Article
Oxidation of Thin Titanium Films: Determination of the Chemical Composition of the Oxide and the Oxygen Diffusion Factor
by Sergey Y. Sarvadii, Andrey K. Gatin, Vasiliy A. Kharitonov, Nadezhda V. Dokhlikova, Sergey A. Ozerin, Maxim V. Grishin and Boris R. Shub
Crystals 2020, 10(2), 117; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10020117 - 14 Feb 2020
Cited by 6 | Viewed by 4049
Abstract
The morphologies and local electronic structures of titanium coatings deposited on the surfaces of highly oriented pyrolytic graphite were determined. Chemical compositions of the oxides formed on the coating surfaces were established. A theoretical model was developed describing the changes in the TiO [...] Read more.
The morphologies and local electronic structures of titanium coatings deposited on the surfaces of highly oriented pyrolytic graphite were determined. Chemical compositions of the oxides formed on the coating surfaces were established. A theoretical model was developed describing the changes in the TiOx oxides (1.75 < x < 2) band gap depending on the duration and temperature of the titanium film annealing procedure in oxygen. The effective activation energy of oxygen diffusion in TiOx (1.75 < x < 2) was determined, and the pre-exponential factor of the diffusion coefficient was estimated. Full article
(This article belongs to the Special Issue Functional Oxide Based Thin-Film Materials (Volume II))
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Review

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20 pages, 7276 KiB  
Review
Thin Films and Glass–Ceramic Composites of Huntite Borates Family: A Brief Review
by Elena A. Volkova, Daniil A. Naprasnikov and Nikolay I. Leonyuk
Crystals 2020, 10(6), 487; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10060487 - 06 Jun 2020
Cited by 1 | Viewed by 2438
Abstract
Rare-earth aluminum borates, RAl3(BO3)4 (where R = Y, Pr–Lu), are of great interest because of their attractive multifunctional properties, depending on their structure and composition. The combination of desirable physical and chemical characteristics makes them promising materials for [...] Read more.
Rare-earth aluminum borates, RAl3(BO3)4 (where R = Y, Pr–Lu), are of great interest because of their attractive multifunctional properties, depending on their structure and composition. The combination of desirable physical and chemical characteristics makes them promising materials for lasers and nonlinear optics. Research focusing on RAl3(BO3)4 (RAB) compounds and their solids solutions has continued for more than five decades and has been reflected in numerous articles and several reviews. The last decade’s enhanced interest is being conducted towards epitaxial layers because of the availability of other possible applications, for instance, as scintillators, visible emitting phosphors or optical waveguides and waveguide lasers. On the other hand, the tendency of borate melts to form glasses makes them attractive for research of micro-crystallization processes in these systems and can be effortless towards finding relatively inexpensive optical glass–ceramic materials with similar composition as alternative components to laser systems. This article reviews the recent progress carried out hitherto on epitaxial layers and glass–ceramic composites of huntite-type rare-earth aluminum borates. Full article
(This article belongs to the Special Issue Functional Oxide Based Thin-Film Materials (Volume II))
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