Article
Chemistry, Multidisciplinary
Xi Wang, Changxu Liu, Congcong Gao, Kaili Yao, Seyed Shayan Mousavi Masouleh, Rodrigo Berte, Haoran Ren, Leonardo de S. Menezes, Emiliano Cortes, Isobel C. Bicket, Haiyu Wang, Ning Li, Zhenglong Zhang, Ming Li, Wei Xie, Yifu Yu, Yurui Fang, Shunping Zhang, Hongxing Xu, Alberto Vomiero, Yongchang Liu, Gianluigi A. Botton, Stefan A. Maier, Hongyan Liang
Summary: Plasmonic nanoparticles are effective in hot-electron-assisted applications, but their narrow resonance region and limited hotspot number have limited the utilization of broadband solar energy. By designing and synthesizing silver fractals inspired by tree branches, researchers have developed structures that can create multiple plasmonic resonances and self-constructed hotspots, allowing for better utilization of hot electrons across a wider spectrum of solar radiation. The results show that fractals with acute tips and narrow gaps can support broadband resonances and numerous randomly distributed hotspots, leading to enhanced efficiency in hot electron generation.
Article
Nanoscience & Nanotechnology
Alexander Vogel, Alicia Ruiz Caridad, Johanna Nordlander, Martin F. Sarott, Quintin N. Meier, Rolf Erni, Nicola A. Spaldin, Morgan Trassin, Marta D. Rossell
Summary: Recent studies have found that oxygen defects on the surface of improper ferroelectric thin films can result in the loss of ferroelectric response. We investigated hexagonal YMnO3 thin films and discovered that the polarization suppression in thinner films is due to oxygen vacancies. We demonstrated that these vacancies form on the film surfaces to screen the large internal electric field. Furthermore, by modifying the oxygen concentration, we can significantly tune the phase transition temperatures. These findings are expected to be applicable to other ferroelectric oxide films, highlighting the importance of controlling oxygen content and cation oxidation states for successful integration in nanoscale applications.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Nanoscience & Nanotechnology
Artyom Assadillayev, Tatsuki Hinamoto, Minoru Fujii, Hiroshi Sugimoto, Mark L. Brongersma, Soren Raza
Summary: Resonant optical nanomaterials, such as silicon, can manipulate highly confined guided waves in the form of surface plasmon polaritons (SPPs) on a subwavelength scale. It has been demonstrated that SPPs in ultrathin metal films can be efficiently launched due to the strong coupling between the Mie resonances of the nanoparticle and the SPP modes. By varying the particle size, the SPP excitation wavelength can be tuned across the entire near-infrared spectrum. Our results suggest that silicon nanoparticles may serve as scatterers of the SPPs supported by the film, paving the way for using high-refractive-index dielectric nanoantennas as compact elements for manipulating highly confined SPPs.
Article
Materials Science, Multidisciplinary
Congli Sun, Michael Street, Chenyu Zhang, Gustaaf Van Tendeloo, Wenyu Zhao, Qingjie Zhang
Summary: The local structures of B in B doped Cr2O3 thin films were investigated using electron energy loss spectroscopy and first-principles calculations. B was found to form either magnetic active BCr4 tetrahedra or various inactive BO3 triangles in the Cr2O3 lattice.
MATERIALS TODAY PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Elena Suvorova, Oleg Uvarov, Kirill Chizh, Alexey A. Klimenko, Philippe A. Buffat
Summary: This study reports experimental results of the quantitative determination of oxygen and band gap measurement in TiNx electrodes in planar TiNx top/La:HfO2/TiNx bottom MIM stacks obtained by plasma enhanced atomic layer deposition on SiO2. The study shows that the oxygen concentration is higher in the TiNxOy bottom electrode compared to the TiNxOy top electrode, and the incorporation of oxygen into TiNx is mainly due to diffusion from SiO2 and HfO2. Furthermore, TiO2 is observed at the interface between the Hf oxide layer and the Ti nitride electrodes as well as at the SiO2 interface.
Article
Chemistry, Physical
Alice Apponi, Domenica Convertino, Neeraj Mishra, Camilla Coletti, Mauro Iodice, Franco Frasconi, Federico Pilo, Narcis Silviu Blaj, Daniele Paoloni, Ilaria Rago, Giovanni De Bellis, Gianluca Cavoto, Alessandro Ruocco
Summary: In this study, accurate transmission measurements of electrons below 1 keV through suspended monolayer graphene were reported. The monolayer graphene was grown using chemical vapor deposition and transferred onto transmission electron microscopy (TEM) grids. The transparency of graphene was obtained by measuring the direct beam current and transmitted current. The experimental results showed a transmission rate ranging from about 20% to about 80% for monolayer graphene within the experimental electron energy range. The high quality and grid coverage of the suspended graphene were confirmed through various characterization techniques. Additionally, evidence of suspended monolayer graphene was observed after annealing the samples in vacuum at 550 degrees C.
Article
Nanoscience & Nanotechnology
Kenan Elibol, Clive Downing, Richard G. Hobbs
Summary: In this work, the fabrication and spectroscopic characterization of subwavelength aluminum nanocavities on suspended SiN x membranes are reported. The volume plasmon (VP) and localized surface plasmon resonance (LSPR) modes of these cavities are revealed and studied using electron energy-loss spectroscopy (EELS) and electromagnetic simulations. Dipolar LSPR modes resonant in the UV and blue regions as well as higher-energy optically dark quadrupolar and hexapolar LSPR modes are observed. The asymmetries in the fabricated nanocavities result in a mode mixing and a shift in dipolar dark LSPR modes.
Article
Materials Science, Multidisciplinary
Mohammad Amin Gharavi, Arnaud le Febvrier, Jun Lu, Grzegorz Greczynski, Bjorn Alling, Rickard Armiento, Per Eklund
Summary: (Ti-0.5, Mg-0.5)N thin films were synthesized by reactive dc magnetron sputtering, exhibiting a rock-salt cubic structure and a LiTiO2-type superstructure. The films have an electrical resistivity of 150 mΩ*cm and a Seebeck coefficient of -25 μV/K. High temperature annealing in a nitrogen atmosphere leads to the formation of the cubic superstructure. Density functional theory calculations show a 0.07 eV direct bandgap for the LiTiO2-type TiMgN2 structure.
Article
Multidisciplinary Sciences
Sandhya Susarla, Pablo Garcia-Fernandez, Colin Ophus, Sujit Das, Pablo Aguado-Puente, Margaret McCarter, Peter Ercius, Lane W. Martin, Ramamoorthy Ramesh, Javier Junquera
Summary: This research utilizes a combination of techniques to probe the electronic structure within polar vortices in oxide superlattices at the atomic scale, finding that the peaks in Ti L-edge spectra systematically shift depending on the position of the Ti4+ cations. First-principles computations and simulations derived from first principles show good agreement with experimental results.
NATURE COMMUNICATIONS
(2021)
Article
Nanoscience & Nanotechnology
Michal Horak, Andrea Konecna, Tomas Sikola, Vlastimil Krapek
Summary: Electron energy loss spectroscopy (EELS) is commonly used to study localized surface plasmon modes of plasmonic antennas, but it has limited spectral resolution and difficulty in resolving closely spaced modes. In this study, we address this issue by analyzing the plasmon modes of a dimer plasmonic antenna composed of two gold discs. We propose metrics based on spectral and spatial sensitivity to resolve the modes and validate them through electrodynamic simulations. Experimental data demonstrate the capability of these metrics to resolve and identify the modes, except for the transverse bonding and antibonding modes. Overall, the spatio-spectral metrics enhance the information extracted from EELS for plasmonic antennas.
Article
Chemistry, Multidisciplinary
Aziz Genc, Javier Patarroyo, Jordi Sancho-Parramon, Raul Arenal, Neus G. Bastus, Victor Puntes, Jordi Arbiol
Summary: Morphological control is essential for fabricating nanostructures with desired plasmonic properties. This study investigates the nanoengineering of plasmon resonances in AuAg nanotubes, including completely hollow nanotubes and hybrid nanotubes with solid Ag and hollow AuAg segments. Both experiments and simulations show that plasmon resonances are strongly present inside the nanotubes due to plasmon hybridization. The hybrid AuAg nanotubes exhibit distinctive plasmonic features, allowing for a broad range of plasmon resonances and the modulation of asymmetrical plasmon distributions.
Article
Materials Science, Coatings & Films
Clemence Badie, Heloise Tissot, Beniamino Sciacca, Maissa K. Barr, Julien Bachmann, Christophe Vallee, Gael Gautier, Thomas Defforge, Vincent Astie, Jean-Manuel Decams, Mikhael Bechelany, Lionel Santinacci
Summary: This study focuses on optimizing TiN plasma-enhanced atomic layer deposition by using two different N-sources: NH3 and N-2. Comprehensive physicochemical characterizations were performed to understand the influence of the N-source nature, their dilution in Ar, and the plasma power on the final properties of the deposited layer. It was found that a 1:1 gas ratio of N-sources:Ar mixture, along with low flows (20 sccm), resulted in the highest growth per cycle (GPC) values. The N-2 plasma exhibited slightly slower deposition but acceptable film quality, making it a nonharmful alternative that can be further improved with optimized reactor geometry.
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
(2023)
Article
Materials Science, Coatings & Films
Abbas Kosari Mehr, Reza Babaei, Ali Kosari Mehr, Mohammad Reza Zamani Meymian
Summary: Titanium chromium nitride (TiCrN) films were prepared using co-sputtering under different nitrogen flow rates, leading to changes in crystal structure and grain size. Micro-Raman spectroscopy revealed the presence of various vibrational transitions, while ultraviolet-visible spectroscopy showed potential applications of these coatings in underwater UV photodetector designs.
SURFACE ENGINEERING
(2021)
Article
Chemistry, Physical
S. van Vliet, A. Troglia, E. Olsson, R. Bliem
Summary: This study combines XPS, grazing-incidence X-ray diffraction, and density functional theory calculations to demonstrate that plasmon excitation energies in transition metal silicides can reflect changes in electronic structure upon formation. By observing shifts in electron energy loss satellites, even basic experimental equipment can be used to study electron structure differences in silicides, making this approach promising for enhancing the chemical sensitivity of surface spectroscopy methods.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Physical
Jan Krajczewski, Aleksandra Michalowska, Radim Ctvrtlik, Libor Nozka, Jan Tomastik, Lukas Vaclavek, Sylwia Turczyniak-Surdacka, Krzyszof Bienskowski, Renata Solarska
Summary: This study compares the SERS activity of TiN and Au nano/micro-structures with the same morphology for the first time. Si pyramids were formed and coated with Au and TiN layers of different thicknesses. The platforms exhibited plasmonic properties in the visible range and were effective SERS platforms. The thickest layers of both Au and TiN showed the highest enhancement factor (EF), and even low concentrations of tartrazine could be detected.
APPLIED SURFACE SCIENCE
(2023)
Review
Optics
Colton Fruhling, Mustafa Goksu Ozlu, Soham Saha, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: This study focuses on the role of epsilon-near-zero (ENZ) materials in optical modulation and explores modulation effects under different configurations. The research finds that maximum modulation typically occurs near the ENZ point and resonances in the ENZ region can further enhance modulation strength.
APPLIED PHYSICS B-LASERS AND OPTICS
(2022)
Article
Nanoscience & Nanotechnology
Zhaxylyk A. Kudyshev, Alexander V. Kildishev, Vladimir M. Shalaev, Alexandra Boltasseva
Summary: The Starshot lightsail project aims to build an ultralight spacecraft that can reach Proxima Centauri b in 20 years with propulsion from a high-power laser array. The project imposes extreme requirements on the lightsail's optical, mechanical, and thermal properties. The framework developed can optimize the lightsail's optical and opto-kinematic properties, opening up pathways to a multi-objective optimization of the entire lightsail propulsion system.
Article
Optics
Zhengyu Huang, Jeffrey A. Fessler, Theodore B. Norris
Summary: This research proposes the use of a focal stack camera as a novel secure imaging device for localizing modified regions in manipulated images. The results show that applying convolutional neural network detection methods to focal stack images achieves significantly better detection accuracy.
Article
Chemistry, Multidisciplinary
Soham Saha, Mustafa Goksu Ozlu, Sarah N. Chowdhury, Benjamin T. Diroll, Richard D. Schaller, Alexander Kildishev, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: The unique properties of emerging photonic materials, conducting nitrides and oxides, are explored in this study. The optical properties of polycrystalline titanium nitride and aluminum-doped zinc oxide can be controlled by tailoring the film thickness. The study demonstrates their potential for ENZ-enhanced photonic applications, including optical circuitry, tunable metasurfaces, and nonlinear optical devices.
ADVANCED MATERIALS
(2023)
Article
Multidisciplinary Sciences
Dehui Zhang, Zhen Xu, Gong Cheng, Zhe Liu, Audrey Rose Gutierrez, Wenzhe Zang, Theodore B. Norris, Zhaohui Zhong
Summary: In this study, the authors propose a new hybrid photoconductive switch design by engineering a hot-carrier fast lane using graphene on silicon. This design allows for a high-speed photoconductive switch without sacrificing the generated power.
NATURE COMMUNICATIONS
(2022)
Article
Optics
Colton Fruhling, Kang Wang, Sarah Chowdhury, Xiaohui Xu, Jeffrey Simon, Alexander Kildishev, Letian Dou, Xiangeng Meng, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: Coherent random lasing in subwavelength quasi-2D perovskite films is observed and studied. Statistical analysis reveals Levy-like intensity fluctuations, replica symmetry breaking confirms random lasing, and spectral and spatial correlation techniques are used to study coherent modes. The observed coherent lasing modes are extended states that result from the random crystal grain structure during fabrication and out-compete diffusive lasing due to their coherence.
LASER & PHOTONICS REVIEWS
(2023)
Article
Chemistry, Multidisciplinary
Xiaohui Xu, Abhishek B. Solanki, Demid Sychev, Xingyu Gao, Samuel Peana, Aleksandr S. Baburin, Karthik Pagadala, Zachariah O. Martin, Sarah N. Chowdhury, Yong P. Chen, Takashi Taniguchi, Kenji Watanabe, Ilya A. Rodionov, Alexander Kildishev, Tongcang Li, Pramey Upadhyaya, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: The negatively charged boron vacancy defect in boron nitride has potential in quantum sensing, but its low quantum efficiency hampers its practical applications. This study demonstrates significantly higher emission enhancements of the defect using low-loss nanopatch antennas, making it a promising high-resolution magnetic field sensor.
Review
Optics
Soham Saha, Ohad Segal, Colton Fruhling, Eran Lustig, Mordecai Segev, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: Recent advances in ultrafast, large-modulation photonic materials have led to the potential development of photonic time crystals. This perspective discusses the promising candidates for photonic time crystals, outlining their modulation speed and depth. The challenges and possible paths to success are also analyzed.
Review
Optics
Eran Lustig, Ohad Segal, Soham Saha, Colton Fruhling, Vladimir M. Shalaev, Lexandra Boltasseva, Mordechai Segev
Summary: Photonic Time-Crystals (PTCs) are materials with periodically and abruptly varying refractive index in time. This medium exhibits unique properties, such as momentum bands separated by gaps where waves can be exponentially amplified, extracting energy from the modulation. This article provides a brief review of PTC concepts, formulates the vision, and discusses the challenges.
Article
Nanoscience & Nanotechnology
Xiaohui Xu, Zachariah O. Martin, Michael Titze, Yongqiang Wang, Demid Sychev, Jacob Henshaw, Alexei S. Lagutchev, Han Htoon, Edward S. Bielejec, Simeon I. Bogdanov, Vladimir M. Shalaev, Alexandra Boltasseva
Summary: Diamond color centers, particularly the negatively charged silicon vacancy (SiV-) center, have been intensively studied for their potential applications in quantum information technologies, biological imaging, and sensing. In this study, we successfully created single SiV- centers in nanodiamonds through ion implantation, exhibiting stable high-purity single-photon emission with narrow linewidths, offering new possibilities for quantum photonics, sensing, and biomedicine.
Article
Nanoscience & Nanotechnology
Omer Yesilyurt, Samuel Peana, Vahagn Mkhitaryan, Karthik Pagadala, Vladimir M. M. Shalaev, Alexander V. V. Kildishev, Alexandra Boltasseva
Summary: This work proposes a neural network based inverse design technique for the realistic design and fabrication of single material variable-index multilayer films. By integrating simulated systematic and random errors, the same neural network that produced the ideal designs can be retrained to compensate for deposition errors and fabrication imperfections. This approach provides a practical and experimentally viable method for designing high-performance single material multilayer films for a wide range of applications.
Article
Physics, Applied
Yuanpeng Wu, Ping Wang, Woncheol Lee, Anthony Aiello, Parag Deotare, Theodore Norris, Pallab Bhattacharya, Mackillo Kira, Emmanouil Kioupakis, Zetian Mi
Summary: Both 2D TMDs and III-V semiconductors are potential platforms for quantum technology, but each with its limitations. 2D TMDs have a large exciton binding energy and customizable quantum properties, but compatibility issues with existing industrial processes. On the other hand, III-nitrides have been widely used in light-emitting devices and power electronics but lack exploitation of excitonic quantum aspects. Recent advancements in 2D III-nitrides have shown promise in achieving room-temperature quantum technologies.
APPLIED PHYSICS LETTERS
(2023)
Article
Multidisciplinary Sciences
Zhaxylyk A. Kudyshev, Demid Sychev, Zachariah Martin, Omer Yesilyurt, Simeon I. Bogdanov, Xiaohui Xu, Pei-Gang Chen, Alexander V. Kildishev, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: One of the main characteristics of optical imaging systems is spatial resolution, which is restricted by the diffraction limit. Recently, classical and quantum super-resolution techniques have been developed to break the diffraction limit. We propose a machine learning-assisted approach for rapid antibunching super-resolution imaging, achieving a 12 times speed-up compared to conventional methods. This framework enables the practical realization of scalable quantum super-resolution imaging devices compatible with various quantum emitters.
NATURE COMMUNICATIONS
(2023)
Article
Quantum Science & Technology
Zachariah O. Martin, Alexander Senichev, Samuel Peana, Benjamin J. Lawrie, Alexei S. Lagutchev, Alexandra Boltasseva, Vladimir M. Shalaev
Summary: A robust process for fabricating intrinsic single-photon emitters in silicon nitride has been established, showing promise for quantum applications. The photophysical properties of these emitters are probed through measurements of optical transition wavelengths, linewidths, and photon antibunching as a function of temperature. Insight into the potential for lifetime-limited linewidths is provided through measurements of inhomogeneous and temperature-dependent broadening of the zero-phonon lines.
ADVANCED QUANTUM TECHNOLOGIES
(2023)
Article
Nanoscience & Nanotechnology
Eran Lustig, Ohad Segal, Soham Saha, Eliyahu Bordo, Sarah N. Chowdhury, Yonatan Sharabi, Avner Fleischer, Alexandra Boltasseva, Oren Cohen, Vladimir M. Shalaev, Mordechai Segev
Summary: We experimentally study optical time-refraction caused by time-interfaces as short as a single optical cycle. By observing the propagation of a probe pulse through a sample with a large refractive index change induced by an intense modulator pulse, we find that increasing the refractive index abruptly leads to red-shifted waves while decreasing it back to the original value causes a subsequent blue-shift. Shortening the temporal width of the modulator pulse leads to a proportionally shorter rise time of the red-shift associated with time-refraction. These experiments are conducted in transparent conducting oxides acting as epsilon-near-zero materials. The findings stimulate questions about the fundamental physics in ultrashort time frames and pave the way for future experiments with photonic time-crystals generated by periodic refractive index changes.
