Special Issue "Synthesis and Modification of Nanostructured Thin Films"

A special issue of Nanomaterials (ISSN 2079-4991).

Deadline for manuscript submissions: 25 April 2019

Special Issue Editor

Guest Editor
Prof. Dr. Ion N. Mihailescu

National Institute for Laser, Plasma and Radiation Physics, Plasma and Radiation Physics, Magurele, Ilfov, Romania
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Special Issue Information

Dear Colleagues,

We invite you to contribute to a Special Issue of Nanomaterials entitled "Synthesis and Modification of Nanostructured Thin Films", which is devoted to nanostructures for applications in science, technology, and biomedicine. We expect new original results and interpretations in the synthesis of nanostructures with a special emphasis on complex characterizations and multifunctional utilizations.

This Special Issue is open to any kind of synthesis process and also includes multiple congruent characterization, complex interpretations of results, and recent applications in multiple fields.

The conviction of the Guest Editor is that many advances should be marked in the field and they deserve an up-to-date review. The authors should refer to previous progress in the field and try to focus on the latest developments within this domain.

We believe that the time has come for such an evaluation. The topics of this issue are quite generous starting from synthesis via characterization and going to last hour applications of nanomaterials.

Prof. Dr. Ion N. Mihailescu
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. Nanomaterials 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.

Keywords

  • Synthesis of nanostructures
  • Methods of synthesis
  • Characterization of thin films and nanoparticles
  • Key technological applications

Published Papers (9 papers)

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Research

Open AccessCommunication The Effects of ZnTe:Cu Back Contact on the Performance of CdTe Nanocrystal Solar Cells with Inverted Structure
Nanomaterials 2019, 9(4), 626; https://doi.org/10.3390/nano9040626
Received: 1 March 2019 / Revised: 8 April 2019 / Accepted: 12 April 2019 / Published: 17 April 2019
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Abstract
CdTe nanocrystal (NC) solar cells have received much attention in recent years due to their low cost and environmentally friendly fabrication process. Nowadays, the back contact is still the key issue for further improving device performance. It is well known that, in the [...] Read more.
CdTe nanocrystal (NC) solar cells have received much attention in recent years due to their low cost and environmentally friendly fabrication process. Nowadays, the back contact is still the key issue for further improving device performance. It is well known that, in the case of CdTe thin-film solar cells prepared with the close-spaced sublimation (CSS) method, Cu-doped CdTe can drastically decrease the series resistance of CdTe solar cells and result in high device performance. However, there are still few reports on solution-processed CdTe NC solar cells with Cu-doped back contact. In this work, ZnTe:Cu or Cu:Au back contact layer (buffer layer) was deposited on the CdTe NC thin film by thermal evaporation and devices with inverted structure of ITO/ZnO/CdSe/CdTe/ZnTe:Cu (or Cu)/Au were fabricated and investigated. It was found that, comparing to an Au or Cu:Au device, the incorporation of ZnTe:Cu as a back contact layer can improve the open circuit voltage (Voc) and fill factor (FF) due to an optimized band alignment, which results in enhanced power conversion efficiency (PCE). By carefully optimizing the treatment of the ZnTe:Cu film (altering the film thickness and annealing temperature), an excellent PCE of 6.38% was obtained, which showed a 21.06% improvement compared with a device without ZnTe:Cu layer (with a device structure of ITO/ZnO/CdSe/CdTe/Au). Full article
(This article belongs to the Special Issue Synthesis and Modification of Nanostructured Thin Films)
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Open AccessArticle Effect of Thickness of Molybdenum Nano-Interlayer on Cohesion between Molybdenum/Titanium Multilayer Film and Silicon Substrate
Nanomaterials 2019, 9(4), 616; https://doi.org/10.3390/nano9040616
Received: 26 March 2019 / Revised: 8 April 2019 / Accepted: 11 April 2019 / Published: 16 April 2019
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Abstract
Titanium (Ti) film has been used as a hydrogen storage material. The effect of the thickness of a molybdenum (Mo) nano-interlayer on the cohesive strength between a Mo/Ti multilayer film and a single crystal silicon (Si) substrate was investigated by X-ray diffraction (XRD), [...] Read more.
Titanium (Ti) film has been used as a hydrogen storage material. The effect of the thickness of a molybdenum (Mo) nano-interlayer on the cohesive strength between a Mo/Ti multilayer film and a single crystal silicon (Si) substrate was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and nano-indenter. Four groups of Si/Mo/Ti multilayer films with different thicknesses of Mo and Ti films were fabricated. The XRD results showed that the introduction of the Mo layer suppressed the chemical reaction between the Ti film and Si substrate. The nano-indenter scratch results demonstrated that the cohesion between the Mo/Ti film and Si substrate decreased significantly with increasing Mo interlayer thickness. The XRD stress analysis indicated that the residual stress in the Si/Mo/Ti film was in-plane tensile stress which might be due to the lattice expansion at a high film growth temperature of 700 °C and the discrepancy of the thermal expansion coefficient between the Ti film and Si substrate. The tensile stress in the Si/Mo/Ti film decreased with increasing Mo interlayer thickness. During the cooling of the Si substrate, a greater decrease in tensile stress occurred for the thicker Mo interlayer sample, which became the driving force for reducing the cohesion between the Mo/Ti film and Si substrate. The results confirmed that the design of the Mo interlayer played an important role in the quality of the Ti film grown on Si substrate. Full article
(This article belongs to the Special Issue Synthesis and Modification of Nanostructured Thin Films)
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Open AccessArticle Preliminary Study of Ge-DLC Nanocomposite Biomaterials Prepared by Laser Codeposition
Nanomaterials 2019, 9(3), 451; https://doi.org/10.3390/nano9030451
Received: 4 February 2019 / Revised: 9 March 2019 / Accepted: 13 March 2019 / Published: 18 March 2019
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Abstract
This paper deals with the synthesis and study of the properties of germanium-doped diamond-like carbon (DLC) films. For deposition of doped DLC films, hybrid laser technology was used. Using two deposition lasers, it was possible to arrange the dopant concentrations by varying the [...] Read more.
This paper deals with the synthesis and study of the properties of germanium-doped diamond-like carbon (DLC) films. For deposition of doped DLC films, hybrid laser technology was used. Using two deposition lasers, it was possible to arrange the dopant concentrations by varying the laser repetition rate. Doped films of Ge concentrations from 0 at.% to 12 at.% were prepared on Si (100) and fused silica (FS) substrates at room temperature. Film properties, such as growth rate, roughness, scanning electron microscopy (SEM) morphology, wavelength dependent X-ray spectroscopy (WDS) composition, VIS-near infrared (IR) transmittance, and biological properties (cytotoxicity, effects on cellular morphology, and ability to produce reactive oxygen species (ROS)) were studied in relation to codeposition conditions and dopant concentrations. The analysis showed that Ge-DLC films exhibit cytotoxicity for higher Ge doping. Full article
(This article belongs to the Special Issue Synthesis and Modification of Nanostructured Thin Films)
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Open AccessArticle Blue Electroluminescent Al2O3/Tm2O3 Nanolaminate Films Fabricated by Atomic Layer Deposition on Silicon
Nanomaterials 2019, 9(3), 413; https://doi.org/10.3390/nano9030413
Received: 18 February 2019 / Revised: 4 March 2019 / Accepted: 8 March 2019 / Published: 11 March 2019
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Abstract
Realization of a silicon-based light source is of significant importance for the future development of optoelectronics and telecommunications. Here, nanolaminate Al2O3/Tm2O3 films are fabricated on silicon utilizing atomic layer deposition, and intense blue electroluminescence (EL) from [...] Read more.
Realization of a silicon-based light source is of significant importance for the future development of optoelectronics and telecommunications. Here, nanolaminate Al2O3/Tm2O3 films are fabricated on silicon utilizing atomic layer deposition, and intense blue electroluminescence (EL) from Tm3+ ions is achieved in the metal-oxide-semiconductor structured luminescent devices based on them. Precise control of the nanolaminates enables the study on the influence of the Tm dopant layers and the distance between every Tm2O3 layer on the EL performance. The 456 nm blue EL from Tm3+ ions shows a maximum power density of 0.15 mW/cm2. The EL intensities and decay lifetime decrease with excessive Tm dopant cycles due to the reduction of optically active Tm3+ ions. Cross-relaxation among adjacent Tm2O3 dopant layers reduces the blue EL intensity and the decay lifetime, which strongly depends on the Al2O3 sublayer thickness, with a critical value of ~3 nm. The EL is attributed to the impact excitation of the Tm3+ ions by hot electrons in Al2O3 matrix via Poole–Frenkel mechanism. Full article
(This article belongs to the Special Issue Synthesis and Modification of Nanostructured Thin Films)
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Open AccessArticle Nonlinear Optical Studies of Gold Nanoparticle Films
Nanomaterials 2019, 9(2), 291; https://doi.org/10.3390/nano9020291
Received: 31 December 2018 / Revised: 3 February 2019 / Accepted: 7 February 2019 / Published: 19 February 2019
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Abstract
Gold films are widely used for different applications. We present the results of third- and high-order nonlinear optical studies of the thin films fabricated from Au nanoparticle solutions by spin-coating methods. These nanoparticles were synthesized by laser ablation of bulk gold in pure [...] Read more.
Gold films are widely used for different applications. We present the results of third- and high-order nonlinear optical studies of the thin films fabricated from Au nanoparticle solutions by spin-coating methods. These nanoparticles were synthesized by laser ablation of bulk gold in pure water using 200 ps, 800 nm pulses. The highest values of the nonlinear absorption coefficient (9 × 10−6 cm W−1), nonlinear refractive index (3 × 10−11 cm2 W−1), and saturation intensity (1.3 × 1010 W cm−2) were achieved using 35 fs, 400 nm pulses. We also determined the relaxation time constants for transient absorption (220 fs and 1.6 ps) at 400 nm. The high-order harmonic generation was studied during propagation of 35 fs, 800 nm pulses through the plasma during the ablation of gold nanoparticle film and bulk gold. The highest harmonic cutoff (29th order) was observed in the plasma containing gold nanoparticles. Full article
(This article belongs to the Special Issue Synthesis and Modification of Nanostructured Thin Films)
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Open AccessArticle Long Low-Loss-Litium Niobate on Insulator Waveguides with Sub-Nanometer Surface Roughness
Nanomaterials 2018, 8(11), 910; https://doi.org/10.3390/nano8110910
Received: 5 October 2018 / Revised: 27 October 2018 / Accepted: 2 November 2018 / Published: 6 November 2018
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Abstract
In this paper, we develop a technique for realizing multi-centimeter-long lithium niobate on insulator (LNOI) waveguides with a propagation loss as low as 0.027 dB/cm. Our technique relies on patterning a chromium thin film coated on the top surface of LNOI into a [...] Read more.
In this paper, we develop a technique for realizing multi-centimeter-long lithium niobate on insulator (LNOI) waveguides with a propagation loss as low as 0.027 dB/cm. Our technique relies on patterning a chromium thin film coated on the top surface of LNOI into a hard mask with a femtosecond laser followed by chemo-mechanical polishing for structuring the LNOI into the waveguides. The surface roughness on the waveguides was determined with an atomic force microscope to be 0.452 nm. The approach is compatible with other surface patterning technologies, such as optical and electron beam lithographies or laser direct writing, enabling high-throughput manufacturing of large-scale LNOI-based photonic integrated circuits. Full article
(This article belongs to the Special Issue Synthesis and Modification of Nanostructured Thin Films)
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Open AccessArticle An Eight-Channel C-Band Demux Based on Multicore Photonic Crystal Fiber
Nanomaterials 2018, 8(10), 845; https://doi.org/10.3390/nano8100845
Received: 29 August 2018 / Revised: 12 October 2018 / Accepted: 15 October 2018 / Published: 17 October 2018
Cited by 6 | PDF Full-text (2761 KB) | HTML Full-text | XML Full-text
Abstract
A novel eight-channel demux device based on multicore photonic crystal fiber (PCF) structures that operate in the C-band range (1530–1565 nm) has been demonstrated. The PCF demux design is based on replacing some air-hole areas with lithium niobate and silicon nitride materials over [...] Read more.
A novel eight-channel demux device based on multicore photonic crystal fiber (PCF) structures that operate in the C-band range (1530–1565 nm) has been demonstrated. The PCF demux design is based on replacing some air-hole areas with lithium niobate and silicon nitride materials over the PCF axis alongside with the appropriate optimizations of the PCF structure. The beam propagation method (BPM) combined with Matlab codes was used to model the demux device and optimize the geometrical parameters of the PCF structure. The simulation results showed that the eight-channel demux can be demultiplexing after light propagation of 5 cm with a large bandwidth (4.03–4.69 nm) and cross-talk (−16.88 to −15.93 dB). Thus, the proposed device has great potential to be integrated into dense wavelength division multiplexing (DWDM) technology for increasing performances in networking systems. Full article
(This article belongs to the Special Issue Synthesis and Modification of Nanostructured Thin Films)
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Open AccessArticle Aqueous Synthesis, Degradation, and Encapsulation of Copper Nanowires for Transparent Electrodes
Nanomaterials 2018, 8(10), 767; https://doi.org/10.3390/nano8100767
Received: 17 August 2018 / Revised: 12 September 2018 / Accepted: 25 September 2018 / Published: 28 September 2018
Cited by 3 | PDF Full-text (12037 KB) | HTML Full-text | XML Full-text
Abstract
Copper nanowires (CuNWs) have increasingly become subjected to academic and industrial research, which is attributed to their good performance as a transparent electrode (TE) material that competes with the one of indium tin oxide (ITO). Recently, an environmentally friendly and aqueous synthesis of [...] Read more.
Copper nanowires (CuNWs) have increasingly become subjected to academic and industrial research, which is attributed to their good performance as a transparent electrode (TE) material that competes with the one of indium tin oxide (ITO). Recently, an environmentally friendly and aqueous synthesis of CuNWs was demonstrated, without the use of hydrazine that is known for its unfavorable properties. In this work, we extend the current knowledge for the aqueous synthesis of CuNWs by studying their up-scaling potential. This potential is an important aspect for the commercialization and further development of CuNW-based devices. Due to the scalability and homogeneity of the deposition process, spray coating was selected to produce films with a low sheet resistance of 7.6 Ω/sq. and an optical transmittance of 77%, at a wavelength of 550 nm. Further, we present a comprehensive investigation of the degradation of CuNWs when subjected to different environmental stresses such as the exposure to ambient air, elevated temperatures, high electrical currents, moisture or ultraviolet (UV) light. For the oxidation process, a model is derived to describe the dependence of the breakdown time with the temperature and the initial resistance. Finally, polymer coatings made of polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA), as well as oxide coatings composed of electron beam evaporated silicon dioxide (SiO2) and aluminum oxide (Al2O3) are tested to hinder the oxidation of the CuNW films under current flow. Full article
(This article belongs to the Special Issue Synthesis and Modification of Nanostructured Thin Films)
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Open AccessArticle Structural and Stress Properties of AlGaN Epilayers Grown on AlN-Nanopatterned Sapphire Templates by Hydride Vapor Phase Epitaxy
Nanomaterials 2018, 8(9), 704; https://doi.org/10.3390/nano8090704
Received: 22 July 2018 / Revised: 29 August 2018 / Accepted: 8 September 2018 / Published: 10 September 2018
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Abstract
In this paper, we report the epitaxial growth and material characteristics of AlGaN (Al mole fraction of 10%) on an AlN/nanopatterned sapphire substrate (NPSS) template by hydride vapor phase epitaxy (HVPE). The crystalline quality, surface morphology, microstructure, and stress state of the AlGaN/AlN/NPSS [...] Read more.
In this paper, we report the epitaxial growth and material characteristics of AlGaN (Al mole fraction of 10%) on an AlN/nanopatterned sapphire substrate (NPSS) template by hydride vapor phase epitaxy (HVPE). The crystalline quality, surface morphology, microstructure, and stress state of the AlGaN/AlN/NPSS epilayers were investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The results indicate that the crystal quality of the AlGaN film could be improved when grown on the AlN/NPSS template. The screw threading dislocation (TD) density was reduced to 1.4 × 109 cm−2 for the AlGaN epilayer grown on the AlN/NPSS template, which was lower than that of the sample grown on a flat c-plane sapphire substrate (6.3 × 109 cm−2). As examined by XRD measurements, the biaxial tensile stress of the AlGaN film was significantly reduced from 1,187 MPa (on AlN/NPSS) to 38.41 MPa (on flat c-plane sapphire). In particular, an increase of the Al content in the overgrown AlGaN layer was confirmed by the TEM observation. This could be due to the relaxation of the in-plane stress through the AlGaN and AlN/NPSS template interface. Full article
(This article belongs to the Special Issue Synthesis and Modification of Nanostructured Thin Films)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Superhard tungsten borides thin films synthesized by the laser ablation and magnetron sputtering method
Authors: J. Chrzanowska-Giżyńska, T. Moscicki, Z. Szymanski
Abstract: Tungsten borides belong to the group of superhard materials which combine high hardness over 40 GPa together with good thermal stability. The growing interest in efficient machining techniques has attracted attention to this group of ceramics as coating layers. In this paper the properties of the superhard tungsten borides coatings are presented. Several thin film deposition methods as pulsed laser deposition (PLD), magnetron sputtering MS) as well as hybrid magnetron sputtering – pulsed laser deposition (MS-PLD) method were used. Surface morphology and microstructure of deposited films was evaluated using atomic force microscope (AFM) or profilometer and scanning electron microscope (SEM), respectively.  The chemical and phase composition was determined using electron diffraction spectroscopy (EDS), X-Ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS). The mechanical properties like Vickers hardness (Hv) and Young's modulus values were obtained by using nanoindentation test. Depending on the deposition technique and experimental conditions, various tungsten boride films were obtained, including WB, WB2, WB3. Each of these compositions was super hard, i.e., Hv exceeded 40 GPa. Based on the results obtained, all three deposition methods were compared and evaluated.
Keywords: superhard materials, tungsten borides, thin films
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