Special Issue "Nanopatterned Functional Materials"

A special issue of Nanomaterials (ISSN 2079-4991). This special issue belongs to the section "Synthesis, Interfaces and Nanostructures".

Deadline for manuscript submissions: closed (30 June 2021) | Viewed by 7974

Special Issue Editors

Prof. Dr. Jose Maria De Teresa
E-Mail Website
Guest Editor
Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, Facultad de Ciencias, 50009 Zaragoza, Spain
Interests: advanced nanolithography techniques by focused ion and electron beams; nano-magnetism and spintronics; nano-superconductivity; new materials (graphene, topological materials, etc.)
Special Issues, Collections and Topics in MDPI journals
Dr. Soraya Sangiao
E-Mail Website
Guest Editor
Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza 50018, Spain and Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza, Zaragoza 50009, Spain
Interests: advanced nanolithography techniques by focused electron and ion beams; spintronics; ultrafast magnetization dynamics; ferromagnetic resonance; spin pumping; ferromagnetic insulators; topological insulators

Special Issue Information

Dear Colleagues,

Functional materials are at the core of modern technologies. In recent decades, the need for miniaturization, integration, and control of novel physical and chemical effects have necessitated the development of strategies for the fabrication of nanopatterned functional materials. Strategies based on bottom-up as well as top-down fabrication approaches have contributed to this global effort, leading to huge progress in technologies such as electronics, energy, information storage, sensors and actuators, catalysis, medicine, etc. This Special Issue dedicated to Nanopatterned Functional Materials aims to attract contributions related to the use of top-down approaches to fabricate materials with sub-micron precision that exhibit functional properties in modern technologies. The Guest Editors encourage submissions related to the application of existing lithography techniques and new lithography developments with the aim of producing nanopatterned materials relevant to any of the mentioned technologies. Some of the lithography techniques that are expected to be involved in the development of such nanomaterials are as follows:

  • Photon-based lithography using UV, EUV, X-rays, etc.
  • Electron-based lithography using focused electron beams such as EBL, FEBID, etc.
  • Ion-based lithography using focused ion beams such as FIB, FIBID, etc.
  • Scanning probe lithography using AFM or STM.
  • Nanoimprinting and related lithographies.
  • Other top-down lithographies: nanostencil lithography, nanosphere lithography, etc.

Besides technology-oriented contributions, the Guest Editors also encourage submissions involving research of novel effects arising from the sub-micron dimensions of the materials in, but not limited to, the following fields:

  • Magnetism and spintronics.
  • Photonics and plasmonics.
  • Superconductivity.
  • Mechanics.
  • Topological and 2D materials.
  • Biomedical applications.

It is our pleasure to invite you to submit manuscripts to this Special Issue on “Nanopatterned Functional Materials”. Review and original research articles are also welcome.

Prof. Jose Maria De Teresa
Dr. Soraya Sangiao
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 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. Nanomaterials 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 2400 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

  • Top-down lithography
  • Nanopatterned materials
  • Functional nanomaterials

Published Papers (6 papers)

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Research

Article
FEBID 3D-Nanoprinting at Low Substrate Temperatures: Pushing the Speed While Keeping the Quality
Nanomaterials 2021, 11(6), 1527; https://doi.org/10.3390/nano11061527 - 09 Jun 2021
Cited by 3 | Viewed by 987
Abstract
High-fidelity 3D printing of nanoscale objects is an increasing relevant but challenging task. Among the few fabrication techniques, focused electron beam induced deposition (FEBID) has demonstrated its high potential due to its direct-write character, nanoscale capabilities in 3D space and a very high [...] Read more.
High-fidelity 3D printing of nanoscale objects is an increasing relevant but challenging task. Among the few fabrication techniques, focused electron beam induced deposition (FEBID) has demonstrated its high potential due to its direct-write character, nanoscale capabilities in 3D space and a very high design flexibility. A limitation, however, is the low fabrication speed, which often restricts 3D-FEBID for the fabrication of single objects. In this study, we approach that challenge by reducing the substrate temperatures with a homemade Peltier stage and investigate the effects on Pt based 3D deposits in a temperature range of 530 °C. The findings reveal a volume growth rate boost up to a factor of 5.6, while the shape fidelity in 3D space is maintained. From a materials point of view, the internal nanogranular composition is practically unaffected down to 10 °C, followed by a slight grain size increase for even lower temperatures. The study is complemented by a comprehensive discussion about the growth mechanism for a more general picture. The combined findings demonstrate that FEBID on low substrate temperatures is not only much faster, but practically free of drawbacks during high fidelity 3D nanofabrication. Full article
(This article belongs to the Special Issue Nanopatterned Functional Materials)
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Article
Temperature Dependence of Stress and Optical Properties in AlN Films Grown by MOCVD
Nanomaterials 2021, 11(3), 698; https://doi.org/10.3390/nano11030698 - 10 Mar 2021
Cited by 5 | Viewed by 1988
Abstract
AlN epilayers were grown on a 2-inch [0001] conventional flat sapphire substrate (CSS) and a nano-patterned sapphire substrate (NPSS) by metalorganic chemical vapor deposition. In this work, the effect of the substrate template and temperature on stress and optical properties of AlN films [...] Read more.
AlN epilayers were grown on a 2-inch [0001] conventional flat sapphire substrate (CSS) and a nano-patterned sapphire substrate (NPSS) by metalorganic chemical vapor deposition. In this work, the effect of the substrate template and temperature on stress and optical properties of AlN films has been studied by using Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible spectrophotometer and spectroscopic ellipsometry (SE). The AlN on NPSS exhibits lower compressive stress and strain values. The biaxial stress decreases from 1.59 to 0.60 GPa for AlN on CSS and from 0.90 to 0.38 GPa for AlN on NPSS sample in the temperature range 80–300 K, which shows compressive stress. According to the TEM data, the stress varies from tensile on the interface to compressive on the surface. It can be deduced that the nano-holes provide more channels for stress relaxation. Nano-patterning leads to a lower degree of disorder and stress/strain relaxes by the formation of the nano-hole structure between the interface of AlN epilayers and the substrate. The low crystal disorder and defects in the AlN on NPSS is confirmed by the small Urbach energy values. The variation in bandgap (Eg) and optical constants (n, k) with temperature are discussed in detail. Nano-patterning leads to poor light transmission due to light scattering, coupling, and trapping in nano-holes. Full article
(This article belongs to the Special Issue Nanopatterned Functional Materials)
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Article
Nanopatterning of Weak Links in Superconducting Oxide Interfaces
Nanomaterials 2021, 11(2), 398; https://doi.org/10.3390/nano11020398 - 04 Feb 2021
Cited by 4 | Viewed by 971
Abstract
The interface between two wide band-gap insulators, LaAlO3 and SrTiO3 (LAO/STO), hosts a quasi-two-dimensional electron gas (q2DEG), two-dimensional superconductivity, ferromagnetism, and giant Rashba spin-orbit coupling. The co-existence of two-dimensional superconductivity with gate-tunable spin-orbit coupling and multiband occupation is of particular interest [...] Read more.
The interface between two wide band-gap insulators, LaAlO3 and SrTiO3 (LAO/STO), hosts a quasi-two-dimensional electron gas (q2DEG), two-dimensional superconductivity, ferromagnetism, and giant Rashba spin-orbit coupling. The co-existence of two-dimensional superconductivity with gate-tunable spin-orbit coupling and multiband occupation is of particular interest for the realization of unconventional superconducting pairing. To investigate the symmetry of the superconducting order parameter, phase sensitive measurements of the Josephson effect are required. We describe an approach for the fabrication of artificial superconducting weak links at the LAO/STO interface using direct high-resolution electron beam lithography and low-energy argon ion beam irradiation. The method does not require lift-off steps or sacrificial layers. Therefore, resolution is only limited by the electron beam lithography and pattern transfer. We have realized superconducting weak links with a barrier thickness of 30–100 nm. The barrier transparency of the weak links can be controlled by the irradiation dose and further tuned by a gate voltage. Our results open up new possibilities for the realization of quantum devices in oxide interfaces. Full article
(This article belongs to the Special Issue Nanopatterned Functional Materials)
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Article
Granular Hall Sensors for Scanning Probe Microscopy
Nanomaterials 2021, 11(2), 348; https://doi.org/10.3390/nano11020348 - 01 Feb 2021
Cited by 3 | Viewed by 860
Abstract
Scanning Hall probe microscopy is attractive for minimally invasive characterization of magnetic thin films and nanostructures by measurement of the emanating magnetic stray field. Established sensor probes operating at room temperature employ highly miniaturized spin-valve elements or semimetals, such as Bi. As the [...] Read more.
Scanning Hall probe microscopy is attractive for minimally invasive characterization of magnetic thin films and nanostructures by measurement of the emanating magnetic stray field. Established sensor probes operating at room temperature employ highly miniaturized spin-valve elements or semimetals, such as Bi. As the sensor layer structures are fabricated by patterning of planar thin films, their adaption to custom-made sensor probe geometries is highly challenging or impossible. Here we show how nanogranular ferromagnetic Hall devices fabricated by the direct-write method of focused electron beam induced deposition (FEBID) can be tailor-made for any given probe geometry. Furthermore, we demonstrate how the magnetic stray field sensitivity can be optimized in situ directly after direct-write nanofabrication of the sensor element. First proof-of-principle results on the use of this novel scanning Hall sensor are shown. Full article
(This article belongs to the Special Issue Nanopatterned Functional Materials)
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Article
Optimization of Pt-C Deposits by Cryo-FIBID: Substantial Growth Rate Increase and Quasi-Metallic Behaviour
Nanomaterials 2020, 10(10), 1906; https://doi.org/10.3390/nano10101906 - 24 Sep 2020
Cited by 5 | Viewed by 1205
Abstract
The Focused Ion Beam Induced Deposition (FIBID) under cryogenic conditions (Cryo-FIBID) technique is based on obtaining a condensed layer of precursor molecules by cooling the substrate below the condensation temperature of the gaseous precursor material. This condensed layer is irradiated with ions according [...] Read more.
The Focused Ion Beam Induced Deposition (FIBID) under cryogenic conditions (Cryo-FIBID) technique is based on obtaining a condensed layer of precursor molecules by cooling the substrate below the condensation temperature of the gaseous precursor material. This condensed layer is irradiated with ions according to a desired pattern and, subsequently, the substrate is heated above the precursor condensation temperature, revealing the deposits with the shape of the exposed pattern. In this contribution, the fast growth of Pt-C deposits by Cryo-FIBID is demonstrated. Here, we optimize various parameters of the process in order to obtain deposits with the lowest-possible electrical resistivity. Optimized ~30 nm-thick Pt-C deposits are obtained using ion irradiation area dose of 120 μC/cm2 at 30 kV. This finding represents a substantial increment in the growth rate when it is compared with deposits of the same thickness fabricated by standard FIBID at room temperature (40 times enhancement). The value of the electrical resistivity in optimized deposits (~4 × 104 µΩ cm) is suitable to perform electrical contacts to certain materials. As a proof of concept of the potential applications of this technology, a 100 µm × 100 µm pattern is carried out in only 43 s of ion exposure (area dose of 23 μC/cm2), to be compared with 2.5 h if grown by standard FIBID at room temperature. The ion trajectories and the deposit composition have been simulated using a binary-collision-approximation Monte Carlo code, providing a solid basis for the understanding of the experimental results. Full article
(This article belongs to the Special Issue Nanopatterned Functional Materials)
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Article
Droplet Coalescence by Selective Wettability Enhancement in Microfluidic Devices
Nanomaterials 2020, 10(4), 737; https://doi.org/10.3390/nano10040737 - 12 Apr 2020
Cited by 4 | Viewed by 1426
Abstract
A new approach for droplet coalescence in microfluidic channels based on selective surface energy alteration is demonstrated. The proposed method involves patterning the surface of cyclic olefin copolymer (COC), a hydrophobic substrate attached to a polydimethylsiloxane hydrophobic microchannel, with graphene oxide (GO) using [...] Read more.
A new approach for droplet coalescence in microfluidic channels based on selective surface energy alteration is demonstrated. The proposed method involves patterning the surface of cyclic olefin copolymer (COC), a hydrophobic substrate attached to a polydimethylsiloxane hydrophobic microchannel, with graphene oxide (GO) using standard microfabrication techniques. Surface wettability and adhesion analyses confirmed the enhancement of the COC surface energy upon GO patterning and the stability of the GO film on COC. Three representative cases are illustrated to demonstrate the effectiveness of the method on the coalescence of droplets for different droplet flow regimes, as well as the effect of changing the size of the patterned surface area on the fusion process. The method achieves droplet coalescence without the need for precise synchronization. Full article
(This article belongs to the Special Issue Nanopatterned Functional Materials)
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