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New Achievements in Nanostructured and Low Dimensional Materials and Systems

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

Deadline for manuscript submissions: closed (31 March 2023) | Viewed by 32943

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Special Issue Editors

Prof. Dr. Valentin Craciun

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1. National Institute of R&D for Laser, Plasma & Radiation Physics, 077125 Magurele, Romania
2. Extreme Light Infrastructure for Nuclear Physics (ELI-NP), IFIN-HH, 077125 Magurele, Romania
Interests: glass-ceramic; thin semiconductor films

Prof. Dr. Felicia Iacomi

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Guest Editor

Faculty of Physics, Alexandru Ioan Cuza University, 700506 Iasi, Romania
Interests: physics of advanced materials–nanoparticle synthesis; thin film deposition (sputtering, thermal vacuum deposition, spin coating); characterization (XRD, XPS, UV-Vis, FTIR, EPR) transport phenomena; functional properties (electrical properties, effect hall, optical properties, magnetic properties, sensing properties); advanced applications
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Prof. Dr. Romulus Tetean

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Faculty of Physics, Babes-Bolyai University, Cluj- Napoca, Romania
Interests: structural; electronic; magnetic and transport properties of different classes of materials; like rare-earth 3d transition metals intermetallic compounds; permanent magnets; nanostructured materials; perovskites; superconducting materials

Special Issue Information

Dear Colleagues,

The Special Issue presents a broad spectrum of studies of novel nanostructured materials (inorganic, organic, hybrid, metamaterials) and low-dimensional systems (nanoparticles, nanostructures, thin films, self-assemblies, membranes, heterostructures, mesoscopic systems, quantum wells and superlattices, etc.) covering their processing techniques, characterization, properties (electrical, piezoelectric, magnetic, optical, sensing, etc.), transport phenomena and interactions, the fundamentals of plasma and laser processes, modelling and design, mesoscopic effects, and applications. The Special Issue’s topics include nanotechnology approaches, modern investigation techniques and new achievements in materials science and condensed matter physics and are of great importance in a wide range of modern and emerging technologies with possible applications in electronics, spintronics, photonics, energy, healthcare, and the environment, as well as having an important impact on modern society.

We are pleased to invite you to publish your experimental and theoretical research and contribute to a complete presentation of the new achievements in nanostructured and low-dimensional materials and systems.

This Special Issue aims to include both reviews and regular research papers that are relevant to any field of study that involves nanostructured and low-dimensional materials and systems. Thus, theoretical and experimental articles will be accepted, along with articles that deal with the synthesis, processing, characterization and use of nanostructured and low-dimensional materials and systems. We encourage scientists to publish their experimental and theoretical research in as much detail as possible.

Prof. Dr. Valentin Craciun
Prof. Dr. Felicia Iacomi
Prof. Dr. Romulus Tetean
Guest Editors

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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.

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Keywords

Nanostructured materials
Low-dimensional materials and systems
Processing techniques
Characterization
Properties
Transport phenomena
Modeling
Mesoscopic effects
Devices
Thin films

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Published Papers (12 papers)

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Research

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16 pages, 4852 KiB

Open AccessEditor’s ChoiceArticle

Single-Charge Tunneling in Codoped Silicon Nanodevices

by Daniel Moraru, Tsutomu Kaneko, Yuta Tamura, Taruna Teja Jupalli, Rohitkumar Shailendra Singh, Chitra Pandy, Luminita Popa and Felicia Iacomi

Nanomaterials 2023, 13(13), 1911; https://doi.org/10.3390/nano13131911 - 22 Jun 2023

Cited by 2 | Viewed by 1852

Abstract

Silicon (Si) nano-electronics is advancing towards the end of the Moore’s Law, as gate lengths of just a few nanometers have been already reported in state-of-the-art transistors. In the nanostructures that act as channels in transistors or depletion layers in pn diodes, the role of dopants becomes critical, since the transport properties depend on a small number of dopants and/or on their random distribution. Here, we present the possibility of single-charge tunneling in codoped Si nanodevices formed in silicon-on-insulator films, in which both phosphorus (P) donors and boron (B) acceptors are introduced intentionally. For highly doped pn diodes, we report band-to-band tunneling (BTBT) via energy states in the depletion layer. These energy states can be ascribed to quantum dots (QDs) formed by the random distribution of donors and acceptors in such a depletion layer. For nanoscale silicon-on-insulator field-effect transistors (SOI-FETs) doped heavily with P-donors and also counter-doped with B-acceptors, we report current peaks and Coulomb diamonds. These features are ascribed to single-electron tunneling (SET) via QDs in the codoped nanoscale channels. These reports provide new insights for utilizing codoped silicon nanostructures for fundamental applications, in which the interplay between donors and acceptors can enhance the functionalities of the devices. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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14 pages, 4232 KiB

Open AccessArticle

The Influence of Zn Substitution on Physical Properties of CoFe₂O₄ Nanoparticles

by Adam Szatmari, Rares Bortnic, Gabriela Souca, Razvan Hirian, Lucian Barbu-Tudoran, Fran Nekvapil, Cristian Iacovita, Emil Burzo, Roxana Dudric and Romulus Tetean

Nanomaterials 2023, 13(1), 189; https://doi.org/10.3390/nano13010189 - 31 Dec 2022

Cited by 6 | Viewed by 3257

Abstract

Co_1−xZn_xFe₂O₄ nanoparticles (0 ≤ x ≤ 1) have been synthesized via a green sol–gel combustion method. The prepared samples were studied using X-ray diffraction measurements (XRD), transmission electron microscopy (TEM), Raman, and magnetic measurements. All samples were found to be single phases and have a cubic Fd-3m structure. EDS analysis confirmed the presence of cobalt, zinc, iron, and oxygen in all studied samples. Raman spectra clearly show that Zn ions are preferentially located in T sites for low Zn concentrations. Due to their high crystallinity, the nanoparticles show high values of the magnetization, which increases with the Zn content for x < 0.5. The magnetic properties are discussed based on Raman results. Co ferrite doped with 30% of Zn produced the largest SAR values, which increase linearly from 148 to 840 W/g_MNPs as the H is increased from 20 to 60 kA/m. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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33 pages, 21104 KiB

Open AccessEditor’s ChoiceArticle

Micromagnetic Design of Skyrmionic Materials and Chiral Magnetic Configurations in Patterned Nanostructures for Neuromorphic and Qubit Applications

by Roxana-Alina One, Sever Mican, Angela-Georgiana Cimpoeșu, Marius Joldos, Romulus Tetean and Coriolan Viorel Tiușan

Nanomaterials 2022, 12(24), 4411; https://doi.org/10.3390/nano12244411 - 10 Dec 2022

Cited by 2 | Viewed by 2608

Abstract

Our study addresses the problematics of magnetic skyrmions, nanometer-size vortex-like swirling topological defects, broadly studied today for applications in classic, neuromorphic and quantum information technologies. We tackle some challenging issues of material properties versus skyrmion stability and manipulation within a multiple-scale modeling framework, involving complementary ab-initio and micromagnetic frameworks. Ab-initio calculations provide insight into the anatomy of the magnetic anisotropy, the Dzyaloshinskii–Moriya asymmetric exchange interaction (DMI) and their response to a gating electric field. Various multi-layered heterostructures were specially designed to provide electric field tunable perpendicular magnetization and sizeable DMI, which are required for skyrmion occurrence. Landau–Lifshitz–Gilbert micromagnetic calculations in nanometric disks allowed the extraction of material parameter phase diagrams in which magnetic textures were classified according to their topological charge. We identified suitable ranges of magnetic anisotropy, DMI and saturation magnetization for stabilizing skyrmionic ground states or writing/manipulating them using either a spin-transfer torque of a perpendicular current or the electric field. From analyzing the different contributions to the total magnetic free energy, we point out some critical properties influencing the skyrmions’ stability. Finally, we discuss some experimental issues related to the choice of materials or the design of novel magnetic materials compatible with skyrmionic applications. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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11 pages, 7297 KiB

Open AccessArticle

Surface Enhancement Using Black Coatings for Sensor Applications

by Martin Hruška, Joris More-Chevalier, Přemysl Fitl, Michal Novotný, Petr Hruška, Dejan Prokop, Petr Pokorný, Jan Kejzlar, Virginie Gadenne, Lionel Patrone, Martin Vrňata and Jan Lančok

Nanomaterials 2022, 12(23), 4297; https://doi.org/10.3390/nano12234297 - 3 Dec 2022

Cited by 7 | Viewed by 1816

Abstract

The resolution of a quartz crystal microbalance (QCM) is particularly crucial for gas sensor applications where low concentrations are detected. This resolution can be improved by increasing the effective surface of QCM electrodes and, thereby, enhancing their sensitivity. For this purpose, various researchers have investigated the use of micro-structured materials with promising results. Herein, we propose the use of easy-to-manufacture metal blacks that are highly structured even on a nanoscale level and thus provide more bonding sites for gas analytes. Two different black metals with thicknesses of 280 nm, black aluminum (B-Al) and black gold (B-Au), were deposited onto the sensor surface to improve the sensitivity following the Sauerbrey equation. Both layers present a high surface roughness due to their cauliflower morphology structure. A high response (i.e., resonant frequency shift) of these QCM sensors coated with a black metal layer was obtained. Two gaseous analytes, H₂O vapor and EtOH vapor, at different concentrations, are tested, and a distinct improvement of sensitivity is observed for the QCM sensors coated with a black metal layer compared to the blank ones, without strong side effects on resonance frequency stability or mechanical quality factor. An approximately 10 times higher sensitivity to EtOH gas is reported for the QCM coated with a black gold layer compared to the blank QCM sensor. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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16 pages, 3318 KiB

Open AccessArticle

Studies of the Structure and Optical Properties of BaSrMgWO₆ Thin Films Deposited by a Spin-Coating Method

by Luciana Punga, Abderrahman Abbassi, Mihaela Toma, Teodor Alupului, Corneliu Doroftei, Marius Dobromir, Daniel Timpu, Florica Doroftei, Laura Hrostea, George G. Rusu, Abdelati Razouk and Felicia Iacomi

Nanomaterials 2022, 12(16), 2756; https://doi.org/10.3390/nano12162756 - 11 Aug 2022

Cited by 6 | Viewed by 1985

Abstract

Highly transparent thin films with the chemical formula BaSrMgWO₆ were deposited by spin coating using a solution of nitrates of Ba, Sr, and Mg and ammonium paratungstate in dimethylformamide with a Ba:Sr:Mg:W ratio = 1:1:1:1. XRD, SEM, EDX, and XPS investigations evidenced that annealing at 800 °C for 1 h results in an amorphous structure having a precipitate on its surface, and that supplementary annealing at 850 °C for 45 min forms a nanocrystalline structure and dissolves a portion of the precipitates. A textured double perovskite cubic structure (61.9%) was found, decorated with tetragonal and cubic impurity phases (12.7%), such as BaO₂, SrO₂, and MgO, and an under-stoichiometric phase (24.4%) with the chemical formula Ba_2−(x+y) Sr_xMg_yWO₅. From transmittance measurements, the values of the optical band gap were estimated for the amorphous (E_gdir = 5.21 eV, E_gind = 3.85 eV) and nanocrystalline (E_gdir = 4.69 eV, E_gind = 3.77 eV) phases. The presence of a lattice disorder was indicated by the high Urbach energy values and weak absorption tail energies. A decrease in their values was observed and attributed to the crystallization process, lattice strain diminution, and cation redistribution. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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28 pages, 10357 KiB

Open AccessArticle

Fe₃O₄-PAA–(HP-γ-CDs) Biocompatible Ferrimagnetic Nanoparticles for Increasing the Efficacy in Superparamagnetic Hyperthermia

by Costica Caizer, Isabela Simona Caizer, Roxana Racoviceanu, Claudia Geanina Watz, Marius Mioc, Cristina Adriana Dehelean, Tiberiu Bratu and Codruța Soica

Nanomaterials 2022, 12(15), 2577; https://doi.org/10.3390/nano12152577 - 27 Jul 2022

Cited by 6 | Viewed by 2228

Abstract

In this paper, we present the obtaining of Fe₃O₄-PAA–(HP-γ-CDs) ferrimagnetic nanobioconjugates (PAA: polyacrylic acid, HP-γ-CDs: hydroxypropyl gamma-cyclodextrins) in a hybrid core-shell biostructure (core: inorganic Fe₃O₄ nanoparticles, and shell: organic PAA–(HP-γ-CDs)) and their use in superparamagnetic hyperthermia without cellular toxicity and with increased efficacy for future alternative cancer therapy. In order to design the optimal experimental conditions for obtaining nanobioconjugates and then superparamagnetic hyperthermia (SPMHT), we used molecular docking simulation and computational assessment of the maximum specific loss power (SLP) that led to nanoparticles’ heating. The nanoparticles and nanobioconjugates obtained were studied and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transformed-infrared spectroscopy (FT-IR), dynamic light scattering (DLS), and magnetic measurements (MMs). The cell viability of the nanoparticles and nanobioconjugates was assessed by means of the MTT assay using human immortalized keratinocytes (HaCaT) as an in vitro model. Superparamagnetic hyperthermia with nanoparticles and nanobioconjugates was obtained experimentally in a magnetic field of 15.92 kA/m and frequency of 312.2 kHz for the magnetic nanoparticle core with a (average) diameter of 15.8 nm, which resulted in the maximum hyperthermic effect that led to a temperature of ~42.5 °C necessary in the therapy of tumors in a short time so as not to affect healthy tissues. The biological screening of Fe₃O₄-PAA nanoparticles and PAA–(HP-γ-CDs) nanobioconjugates showed no cytotoxic effect on HaCaT cells for a time interval of 24 h, both under standard (37 °C) and hyperthermia conditions (42.5 °C). Thus, Fe₃O₄-PA–(HP-γ-CDs) ferrimagnetic nanobioconjugates can be used successfully in superparamagnetic hyperthermia without toxicity and with increased efficiency due to the small layer thickness of the PAA–(HP-γ-CDs) shell, which is suitable in this alternative therapeutic technique. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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13 pages, 717 KiB

Open AccessArticle

Tailoring of Multisource Deposition Conditions towards Required Chemical Composition of Thin Films

by Jan Gutwirth, Magdaléna Kotrla, Tomáš Halenkovič, Virginie Nazabal and Petr Němec

Nanomaterials 2022, 12(11), 1830; https://doi.org/10.3390/nano12111830 - 27 May 2022

Cited by 2 | Viewed by 4848

Abstract

The model to tailor the required chemical composition of thin films fabricated via multisource deposition, exploiting basic physicochemical constants of source materials, is developed. The model is experimentally verified for the two-source depositions of chalcogenide thin films from Ga–Sb–Te system (tie-lines GaSb–GaTe and GaSb–Te). The thin films are deposited by radiofrequency magnetron sputtering using GaSb, GaTe, and Te targets. Prepared thin films are characterized by means of energy dispersive X-ray analysis coupled with a scanning electron microscope to determine the chemical composition and by variable angle spectroscopic ellipsometry to establish film thickness. Good agreement between results of calculations and experimentally determined compositions of the co-deposited thin films is achieved for both the above-mentioned tie-lines. Moreover, in spite of all the applied simplifications, the proposed model is robust to be generally used for studies where the influence of thin film composition on their properties is investigated. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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17 pages, 4200 KiB

Open AccessArticle

Deposition of Nanosized Amino Acid Functionalized Bismuth Oxido Clusters on Gold Surfaces

by Annika Morgenstern, Rico Thomas, Apoorva Sharma, Marcus Weber, Oleksandr Selyshchev, Ilya Milekhin, Doreen Dentel, Sibylle Gemming, Christoph Tegenkamp, Dietrich R. T. Zahn, Michael Mehring and Georgeta Salvan

Nanomaterials 2022, 12(11), 1815; https://doi.org/10.3390/nano12111815 - 26 May 2022

Cited by 3 | Viewed by 2403

Abstract

Bismuth compounds are of growing interest with regard to potential applications in catalysis, medicine, and electronics, for which their environmentally benign nature is one of the key factors. One thing that currently hampers the further development of bismuth oxido-based materials, however, is the often low solubility of the precursors, which makes targeted immobilisation on substrates challenging. We present an approach towards the solubilisation of bismuth oxido clusters by introducing an amino carboxylate as a functional group. For this purpose, the bismuth oxido cluster [Bi₃₈O₄₅(NO₃)₂₀(dmso)₂₈](NO₃)₄·4dmso (dmso = dimethyl sulfoxide) was reacted with the sodium salt of tert-butyloxycabonyl (Boc)-protected phenylalanine (L-Phe) to obtain the soluble and chiral nanocluster [Bi₃₈O₄₅(Boc–Phe–O)₂₄(dmso)₉]. The exchange of the nitrates by the amino carboxylates was proven by nuclear magnetic resonance, Fourier-transform infrared spectroscopy, as well as elemental analysis and X-ray photoemission spectroscopy. The solubility of the bismuth oxido cluster in a protic as well as an aprotic polar organic solvent and the growth mode of the clusters upon spin, dip, and drop coating on gold surfaces were studied by a variety of microscopy, as well as spectroscopic techniques. In all cases, the bismuth oxido clusters form crystalline agglomerations with size, height, and distribution on the substrate that can be controlled by the choice of the solvent and of the deposition method. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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11 pages, 3641 KiB

Open AccessEditor’s ChoiceArticle

Unexpected Phonon Behaviour in BiFe_xCr_1−xO₃, a Material System Different from Its BiFeO₃ and BiCrO₃ Parents

by Cameliu Himcinschi, Felix Drechsler, David Sebastian Walch, Akash Bhatnagar, Alexei A. Belik and Jens Kortus

Nanomaterials 2022, 12(9), 1607; https://doi.org/10.3390/nano12091607 - 9 May 2022

Cited by 4 | Viewed by 2262

Abstract

The dielectric function and the bandgap of BiFe_0.5Cr_0.5O₃ thin films were determined from spectroscopic ellipsometry and compared with that of the parent compounds BiFeO₃ and BiCrO₃. The bandgap value of BiFe_0.5Cr_0.5O₃ is lower than that of BiFeO₃ and BiCrO₃, due to an optical transition at ~2.27 eV attributed to a charge transfer excitation between the Cr and Fe ions. This optical transition enables new phonon modes which have been investigated using Raman spectroscopy by employing multi-wavelengths excitation. The appearance of a new Raman mode at ~670 cm⁻¹ with a strong intensity dependence on the excitation line and its higher order scattering activation was found for both BiFe_0.5Cr_0.5O₃ thin films and BiFe_xCr_1−xO₃ polycrystalline bulk samples. Furthermore, Raman spectroscopy was also used to investigate temperature induced structural phase transitions in BiFe_0.3Cr_0.7O₃. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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13 pages, 10186 KiB

Open AccessEditor’s ChoiceArticle

New Insights into the Magnetic Properties of CoFe₂O₄@SiO₂@Au Magnetoplasmonic Nanoparticles

by Rareș Bortnic, Adam Szatmari, Gabriela Souca, Răzvan Hirian, Roxana Dudric, Lucian Barbu-Tudoran, Valentin Toma, Rareș Știufiuc, Romulus Tetean and Emil Burzo

Nanomaterials 2022, 12(6), 942; https://doi.org/10.3390/nano12060942 - 12 Mar 2022

Cited by 7 | Viewed by 3976

Abstract

We report the successful synthesis and a complete magnetic characterization of CoFe₂O₄@SiO₂@Au magnetoplasmonic nanoparticles. The CoFe₂O₄ magnetic nanoparticles were prepared using the hydrothermal method. A subsequent SiO₂ shell followed by a plasmonic Au shell were deposited on the magnetic core creating magnetoplasmonic nanoparticles with a core–shell architecture. A spin-glass-type magnetism was shown at the surface of the CoFe₂O₄ nanograins. Depending on the external magnetic field, two types of spin-glass were identified and analyzed in correlation with the exchange field acting on octahedral and tetrahedral iron sites. The magnetization per formula unit of the CoFe₂O₄ core is not changed in the case of CoFe₂O₄@SiO₂@Au nanocomposites. The gold nanoparticles creating the plasmonic shell show a giant diamagnetic susceptibility, dependent on their crystallite sizes. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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19 pages, 5781 KiB

Open AccessArticle

A Novel Synthesis of ZnO Nanoflower Arrays Using a Lift-Off Technique with Different Thicknesses of Al Sacrificial Layers on a Patterned Sapphire Substrate

by Hsien-Wei Tseng, Ching-Shan Wang, Fang-Hsing Wang, Han-Wen Liu and Cheng-Fu Yang

Nanomaterials 2022, 12(4), 612; https://doi.org/10.3390/nano12040612 - 11 Feb 2022

Cited by 5 | Viewed by 1761

Abstract

A novel method to synthesize large-scale ZnO nanoflower arrays using a protrusion patterned ZnO seed layer was investigated. Different thicknesses of aluminum (Al) film were deposited on the concave patterned sapphire substrate as a sacrificial layer. ZnO gel was layered onto the Al film as a seed layer and OE-6370HF AB optical glue was used as the adhesive material. A lift-off technique was used to transfer the protrusion patterned ZnO/AB glue seed layer to a P-type Si <100> wafer. The hydrothermal method using Zn(CH₃COO)₂ and C₆H₁₂N₄ solutions as liquid precursors was used to synthesize ZnO nanoflower arrays on the patterned seed layer. X-ray diffraction spectra, field-effect scanning electron microscopy, focused ion beam milling (for obtaining cross-sectional views), and photoluminescence (PL) spectrometry were used to analyze the effects that different synthesis times and different thicknesses of Al sacrificial layer had on the properties of ZnO nanoflower arrays. These effects included an increased diameter, and a decreased height, density (i.e., number of nanorods in μm⁻²), total surface area, total volume, and maximum emission intensity of PL spectrum. We showed that when the synthesis time and the thickness of the Al sacrificial layer were increased, the emission intensities of the ultraviolet light and visible light had different variations. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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16 pages, 65520 KiB

Open AccessReview

Surface- and Tip-Enhanced Raman Scattering by CdSe Nanocrystals on Plasmonic Substrates

by Ilya A. Milekhin, Alexander G. Milekhin and Dietrich R. T. Zahn

Nanomaterials 2022, 12(13), 2197; https://doi.org/10.3390/nano12132197 - 26 Jun 2022

Cited by 5 | Viewed by 2473

Abstract

This work presents an overview of the latest results and new data on the optical response from spherical CdSe nanocrystals (NCs) obtained using surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS). SERS is based on the enhancement of the phonon response from nanoobjects such as molecules or inorganic nanostructures placed on metal nanostructured substrates with a localized surface plasmon resonance (LSPR). A drastic SERS enhancement for optical phonons in semiconductor nanostructures can be achieved by a proper choice of the plasmonic substrate, for which the LSPR energy coincides with the laser excitation energy. The resonant enhancement of the optical response makes it possible to detect mono- and submonolayer coatings of CdSe NCs. The combination of Raman scattering with atomic force microscopy (AFM) using a metallized probe represents the basis of TERS from semiconductor nanostructures and makes it possible to investigate their phonon properties with nanoscale spatial resolution. Gap-mode TERS provides further enhancement of Raman scattering by optical phonon modes of CdSe NCs with nanometer spatial resolution due to the highly localized electric field in the gap between the metal AFM tip and a plasmonic substrate and opens new pathways for the optical characterization of single semiconductor nanostructures and for revealing details of their phonon spectrum at the nanometer scale. Full article

(This article belongs to the Special Issue New Achievements in Nanostructured and Low Dimensional Materials and Systems)

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