Aluminum for Plasmonics (original) (raw)
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Aluminum based nanostructures for energy applications
TELKOMNIKA Telecommunication, Computing, Electronics and Control, 2021
The plasmonic material properties of aluminum allow active plasmon resonances extending from the blue color in the visible range to the ultraviolet (UV) region of the spectrum. Whereas Al is usually avoided for applications of plasmonics due to its losses in the infrared spectrum region. In this work, the study of the scatter and absorption of disk nanoantennas (DNAs) using various types of materials Au, Ag, and Al is accomplished by using the CST microwave studio suite simulation. The results showed that Al can offer good plasmonic properties when DNA radius is 25 nm to 125 nm at 20 nm height and working wavelengths longer than 800 nm in the near-infrared (NIR) region. Al produces negative plasmonic features around 800 nm wavelength due to the interband transition in the imaginary part of epsilon. For Au and Ag, the plasmonic characteristics rapidly decayed when the DNA radius was higher than 60 nm, but in contrast, Al offers good plasmonic features at these large dimensions of DNAs. This extended response of Al in UV, visible, and NIR, incorporated with its low cost, natural abundance, low native oxide, and amenability to industrial processes, could make Al an extremely promising plasmonic metal candidate for energy applications. This is an open access article under the CC BY-SA license. 1. INTRODUCTION Metallic nanostructures have been under intensive investigation becauce of their plasmonic properties and ability to interact with light at subwavelength dimensions [1-3]. Studies of coherent oscillations of electrons in the optical metals, which are recognized as localized surface plasmon resonances (LSPR), were based on the dielectric properties of metals. The resonance wavelength of the plasmonic systems in common depends mainly on the metal nanoparticle size, geometry, and the real and imaginary parts of the dielectric of metal nanoparticles , which are the dispersion properties of the metal [4, 5]. The researchers were highly concentrated on Au and Ag because of their optical and dielectric properties, which could be deployed in different applications. For instance, Ag based nanosensors [6], plasmonic waveguides [7], tunable plasmonic filters [8], nanoantennas for field enhancement [9], nonlinear devices [10], and nanotechnology for energy applications [11, 12]. However, Au and Ag work at wavelengths down to 600 nm. Au is an expensive material, where Ag suffers from rapid oxidation that degrades plasmonic properties. These problems need to be considered when we choose the appropriate material. Even though, Al shows large losses at the interband wavelength around 800 nm. From blue color in the visible region up to the UV region of the spectrum, Al shows low loss and represents a promising plasmonic material [13-15].
Al clusters have drawn tremendous attention of scientific community for their characteristic deep ultraviolet plasmonic emission. In this study, we have explored the plasmonic characteristics of a series of linear (Aln; n = 2 to 9) and cyclic aluminum clusters (n = 3,4) along with our recently reported three Al13+ isomer system [Guin et. al. Journal of Molecular Graphics and Modeling, 2020, 97, 107544] and corresponding alkali doped clusters [Guin et. al. Journal of Molecular Modeling, 2021, 27, 235]. Among the three Al13+ isomers one is perfectly planar (CI) and two others are quasi-planar clusters (CT and CII). It is a well-known fact that properties of nano-clusters strongly depend on the size and shape of the clusters. The current study reveals that for the linear chains the plamonic character systematically increases with the nuclearity of the clusters. For the cyclic clusters (Al3 and Al4) the plamonicity is lower compared to corresponding linear clusters. In case of Al13+ iso...
The localized surface plasmon resonance (LSPR) of aluminum nanospheres, nanorods, and nanodisks was studied using the finite-difference time-domain (FDTD) method. From the simulation results, optimal dimensions of nanospheres, nanodisks, and nanorods for refractive index sensitivity (RIS), line shape broadening (FWHM), and figure-of-merit (FOM) are calculated for aluminum-based plasmonic nanosensors. Our calculated results show that aluminum is an efficient plasmonic material for refractive index sensing from deep-UV to near infrared wavelengths. The RIS of aluminum nanospheres of optimal size is greater than gold and silver nanospheres. Further, RIS or FOM can be optimized in different spectral region by varying shape and dimensions. The optimization reveals higher FOM for nanospheres in the deep-UV region and for nanorods and nanodisks in the broad visible-NIR region.
Localization, Hybridization, and Coupling of Plasmon Resonances in an Aluminum Nanomatryushka
In this study, we investigate the plasmon response of two concentric aluminum (Al) nanoshells as a nanomatryushka unit to introduce a novel compositional structure that has a strong potential to employ in designing practical nanoscale plasmonic devices. Herein, we employed Al nanoshells with a coverage of oxide (Al 2 O 3) layer with certain and homogenous size of thickness in inner and outer sides. Using plasmon hybridization theory and finite-difference time-domain (FDTD) method as numerical model, we calculated and sketched the optical response and energy level diagram for the studied structure. Strong plasmon resonances are reported in the UV and visible wavelengths that can be supported efficiently by using the proposed nanomatryushka unit composed of Al/Al 2 O 3 on a SiO 2 surface. Utilizing presented nanomatryushka in designing an artificial dimer configuration, the possibility of appearing of dark modes and formation of Fano resonances in such a symmetric structure in the UV and visible spectra are verified numerically. Immersing the presented dimer in various liquids with different refractive indices, the behavior of Fano dip is investigated and corresponding figure of merit (FoM) is quantified based on the plasmon resonance energy shifts over the refractive index variations. This understating opens novel avenues to obtain sharp and deep Fano resonances in simple and low-cost structures that have strong potentials in fabrication of biochemical sensors, superlensing, and biological agents.
Exploiting Native Al 2 O 3 for Multispectral Aluminum Plasmonics
ACS Photonics, 2014
Aluminum, despite its abundance and low cost, is usually avoided for plasmonic applications due to losses in visible/infrared regimes and its interband absorption at 800 nm. Yet, it is compatible with silicon CMOS processes, making it a promising alternative for integrated plasmonic applications. It is also well known that a thin layer of native Al 2 O 3 is formed on aluminum when exposed to air, which must be taken into account properly while designing plasmonic structures. Here, for the first time we report exploitation of the native Al 2 O 3 layer for fabrication of periodic metal−insulator−metal (MIM) plasmonic structures that exhibit resonances spanning a wide spectral range, from the nearultraviolet to mid-infrared region of the spectrum. Through fabrication of silver nanoislands on aluminum surfaces and MIM plasmonic surfaces with a thin native Al 2 O 3 layer, hierarchical plasmonic structures are formed and used in surface-enhanced infrared spectroscopy (SEIRA) and surface-enhanced Raman spectrocopy (SERS) for detection of self-assembled monolayers of dodecanethiol.
Effects of oxidation on the plasmonic properties of aluminum nanoclusters
Nanoscale, 2017
The scouting of alternative plasmonic materials able to enhance and extend the optical properties of noble metal nanostructures is on the rise. Aluminum is endowed with a set of interesting properties which turn it into an attractive plasmonic material. Here we present the optical and electronic features of different aluminum nanostructures stemming from a multilevel computational study. Molecular Dynamics (MD) simulations using a reactive force field (ReaxFF), carefully validated with Density Functional Theory (DFT), were employed to mimic the oxidation of icosahedral aluminum nanoclusters. Resulting structures with different oxidation degrees were then studied through the Time-Dependent Density Functional Tight Binding (TD-DFTB) method. A similar approach was used in aluminum nanoclusters with a disordered structure to study how the loss of crystallinity affects the optical properties. To the best of our knowledge, this is the first report that addresses this issue from the fully ...
Applied Physics Letters, 2012
Localized surface plasmon resonances were controlled at deep-ultraviolet (DUV) wavelengths by fabricating aluminum (Al) nanostructures in a size-controllable manner. Plasmon resonances were obtained at wavelengths from near-UV down to 270 nm (4.6 eV) depending on the fabricated structure size. Such precise size control was realized by the nanosphere lithography technique combined with additional microwave heating to shrink the spaces in a close-packed monolayer of colloidal nanosphere masks. By adjusting the microwave heating time, the sizes of the Al nanostructures could be controlled from 80 nm to 50 nm without the need to use nanosphere beads of different sizes. With the outstanding controllability and versatility of the presented fabrication technique, the fabricated Al nanostructure is promising for use as a DUV plasmonic substrate, a light-harvesting platform for mediating strong light-matter interactions between UV photons and molecules placed near the metal nanostructure. V
Micro and Nanosystems, 2021
Background: A relatively narrow LSPR peak and a strong interband transition ranging around 800 nm make Al a strongly plasmonic active material. Usually, Al nanoparticles are preferred for UV-plasmonic as the SPR of small size Al nanoparticles is located in the deep UV-UV region of the optical spectrum. This paper focused on tuning the LSPR of Al nanostructure towards the infrared region by coating the Au layer. The proposed structure has Au as the outer layer, which prevents further oxidation of Al nanostructure. Methods: The Finite Difference Time Domain (FDTD) and Plasmon Hybridization Theory has been used to evaluate the LSPR and field enhancement of single and dimer Al-Al2O3-Au MDM nanostructure. Results: It is observed that the resonance mode shows dependence on the thickness of the Al2O3 layer and also on the composition of the nanostructure. The Au layered MDM nanostructure shows two peaks of equal intensities simultaneously in UV and visible region tuned to the NIR region. T...
Plasmonic Breathing and Edge Modes in Aluminum Nanotriangles
ACS Photonics, 2017
We use electron energy loss spectroscopy (EELS) to perform a comprehensive spectroscopy and mapping of the plasmonic modes sustained by aluminum nanotriangles. Behind the apparent simplicity of such structures, a rich variety of plasmonic modes is observed. Edge modes and pseudoradial breathing modes (pseudo-RBMs) are unveiled as they couple efficiently with the electron source. We propose analytical models confirmed by rigorous simulations to index both families of modes and describe their spatial symmetry. Edge modes could be indexed as nanoantenna modes, while pseudo-RBMs match triangular cavities ones. The dispersion relation of both modes is measured highlighting their different nature. Plasmonic resonances ranging from near-infrared (IR) to ultraviolet (UV) are obtained by varying the triangle sizes, and especially, we found pseudo-RBMs resonances in the UV region, making them interesting for UV applications.