Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session V21: Nanostructures and Metamaterials -- Active SystemsFocus
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Sponsoring Units: DMP Chair: Viktor Podolskiy, University of Massachusetts Lowell Room: BCEC 157B |
Thursday, March 7, 2019 2:30PM - 3:06PM |
V21.00001: Control of Emission and Energy Transfer with Metamaterials, Plasmonic Structures and Cavities Invited Speaker: Mikhail Noginov Metamaterials, plasmonic structures and cavities have been shown to enable and control scores of spontaneous emission, stimulated emission, and energy transfer phenomena. The recent findings of our group in this research area will be discussed at the conference. |
Thursday, March 7, 2019 3:06PM - 3:18PM |
V21.00002: Mechanisms of GaN quantum dot formation during nitridation of Ga droplets Hongling Lu, Caleb Reese, Sunyeol Jeon, Yaming Fan, Emily Rizzi, Yuqun Zhuo, Liang Qi, Rachel Goldman GaN-based quantum dots (QDs) have been proposed for a variety of optoelectronic devices. Typically, QD formation is driven by a Stranski-Krastanov growth mode transition. Alternatively, the nucleation and conversion of metal droplets to QDs via nitridation, known as droplet epitaxy (DE), has emerged as a promising approach to achieve strain-free QDs. To date, GaN DE has been described as a liquid-phase epitaxy-like and/or a surface-diffusion driven process. Here, we investigate the formation mechanisms for DE GaN QDs using a combined computational-experimental approach. Our first-principles calculations of activation barriers suggest that N is immobile while Ga has a relatively high surface diffusivity, independent of the starting surface structure and chemistry. We consider the temperature and substrate dependence of the size distributions of droplets and QDs, and report on two competing mechanisms mediated by Ga surface diffusion, Ga droplet coarsening with QD formation via impinging N atoms and Ga droplet out-diffusion with QD nucleation at absorbed N surface sites. We also discuss the relative roles of nucleation and coarsening dominant growth, as well as the phase selection, on various substrates. |
Thursday, March 7, 2019 3:18PM - 3:30PM |
V21.00003: Spectrally selective optoelectronic films via photonic band engineering in absorbing media Botong Qiu, Yida Lin, Ebuka S. Arinze, Arlene Chiu, Lulin Li, Susanna M Thon In technologies requiring fine-tuned spectral responsivity such as finite bandwidth photon detection and multijunction solar cells, optoelectronic devices based on traditional semiconductors usually have to integrate external filters or empirically control the thicknesses of each absorbing layer. In this work, we propose an alternate solution that could realize spectral selectivity within the optoelectronic thin film itself: engineering photonic bands within the absorbing region of a semiconductor where the in-plane photonic modes couple strongly to the normal-incidence light at the γ point to tune the out-of-plane reflectivity and transmission spectra. Our optical simulations show that even in the presence of material absorption, we can use photonic crystal structures to tune the strong Fano resonance features in the out-of-plane transmission and reflection spectra induced by the in-plane photonic bands for spectral selectivity. Experimentally, we demonstrate a proof-of-principle photonic structure where a self-assembled polystyrene bead monolayer is infiltrated with PbS colloidal quantum dots for enhanced visible transparency, qualitatively matching predictions and showing promise for multijunction and transparent photovoltaics. |
Thursday, March 7, 2019 3:30PM - 3:42PM |
V21.00004: Harnessing Evanescent Waves by Metasurfaces: An All-Optical Analogue of On-Chip Control of Smith-Purcell Emission Lin Li, Kan Yao, Zuojia Wang, Yongmin Liu
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Thursday, March 7, 2019 3:42PM - 3:54PM |
V21.00005: Radiative spontaneous decay enhancement near an ultrathin plasmonic film Hamze Mousavi, Igor Bondarev We develop a quantum electrodynamics theory for the spontaneous decay process of a point dipole emitter near a thin metallic film. It was previously shown that the strong vertical electron confinement causes the film plasma frequency to become spatially dispersive[1], resulting in a (confinement induced) nonlocal dielectric response of the film[2]. Using this fact we calculate the electromagnetic Green's function and the emitter-to-surface distance dependence for the dipole spontaneous decay rate near the metallic film of finite thickness. We show that the confinement induced dielectric response nonlocality of the ultrathin films can result in a two-order-of-magnitude radiative decay rate enhancement relative to vacuum. The effect can be qualitatively understood in terms of the interacting image dipoles and can be controlled by varying the material composition, the thickness and the surroundings of the film. The inelastic electron scattering diminishes the effect. These are the universal peculiarities of the light-matter interactions in close proximity to ultrathin plasmonic nanostructures. -- [1] I.V.Bondarev & V.M.Shalaev, Opt. Mater. Expr. 7, 3731 (2017); [2] I.V.Bondarev, H.Mousavi, & V.M.Shalaev, MRS Commun. 8, 1092 (2018). |
Thursday, March 7, 2019 3:54PM - 4:06PM |
V21.00006: A correlation study of PbS nanoparticles synthesis conditions and material properties using XRD analysis Gen Long, Elmustapha Feddi, El Mostapha Lotfi, Mostafa Sadoqi PbS nanomaterials display various promising properties that have a wide range of applications in thermoelectrics, photovoltaics, infra-red sensor, etc. In this poster, we report a systematic study of syntheses of lead sulfide (PbS) nanostructures via varying growth temperature (50°C to 120°C), growth time (10min to 24hrs), precursor materials, precursor ratios (Pb: S), etc. The correlations of growth conditions and morphology as well material properties are studied by UV-VIS absorption, XRD, EDS, TEM, etc. XRD data were analyzed in details to reveal the relations between growth conditions and materials properties. Spin-cast photovoltaic devices made of synthesized nanoparticles combined with other nanostructures (TiO2 and ZnO, layer or nanorod) were also characterized and found out to be highly dependent on the growth conditions of syntheses and device fabrication conditions. Introducing plasmonic (Au or Ag) nanoparticles into PbS nanoparticles have also proved to enhance the photocurrent as well as power conversion efficiency. Further engineering of synthesis of PbS nanoparticles and architecture of nanostructures will likely increase the photovoltaic device performance. |
Thursday, March 7, 2019 4:06PM - 4:18PM |
V21.00007: Yagi-Uda nanolithographic antennas on a Si photodiode for infrared detection William Rieger, Jean Heremans, Hang Ruan, Yuhong Kang, Richard Claus, Tigran Asryan Nanoscale Yagi-Uda antennas were fabricated on a metal-semiconductor-metal rectifying photodetector to enhance detector efficiency. A new approach for characterizing the nanolithographic optical antennas was based on a direct electrical measurement obviating the need for an ITO coating or back contact. The measurements demonstrate control of directivity and wavelength selectivity in an array of 400 nanoantennas. With incident light nearly aligned to the center lobe of the Yagi-Udas, resonances in measured photocurrent were observed at 1110 nm and 1690 nm. These correspond to scaled effective wavelengths of 388 nm and 776 nm, respectively, in agreement with plasmonic theory. Estimated quantum efficiencies are 5.1% and 3.1% at 1110 nm and 1690 nm, respectively, representing a fourfold increase over a device lacking the antenna array. The spatial dependence of the contribution of individual antennas in the array has been investigated to determine the process whereby resonant plasmons contribute to the photocurrent. Associated finite element modeling results will be discussed, aimed at predicting resonances in plasmonic structures with similar geometries. |
Thursday, March 7, 2019 4:18PM - 4:30PM |
V21.00008: Theoretical Investigation of Plasmonic Properties of Quantum-Sized Silver Nanoparticles Masoud Shabaninezhad Navrood, Ramakrishna Guda Metallic nanoparticles (NPs) can strongly absorb the incident light and produce enhanced localized electric field when the frequency of the incident light is in phase with coherent oscillation of conduction electrons in them. This characteristic feature of metallic NPs can be tuned by changing parameters such as size, shape, polarization direction of incident light and refractive index of medium. Although plasmonic properties of larger size nanoparticles are extensively investigated, little has been done on smaller sized particles in the size range of 3 to 10 nm. By reducing the size, band structure of the metalic particles discretizes, leading channeling plasmon properties of the NPs from classical to quantum regime. In this work, plasmonic properties of the spherical silver (Ag) NPs in the size range of 3 to 20 nm has been investigated using both quantum and classical model. We performed theoretical calculations using normal Mie theory, and studied size and surrounding medium effects on the absorption efficiency, LSPR energy peak shift and field enhancement of the samples. The results indicate that the quantum model is able to predict blue shift of LSPR peak with decreasing size of the samples from 10 to 3 nm while the classical model fails to observe this effect. |
Thursday, March 7, 2019 4:30PM - 4:42PM |
V21.00009: Networks of helical, braided quantum wells Alexandra Courtis Architectures with complex and reconfigurable topologies present in a series of naturally occurring systems that have precise nanoscale organization and that execute efficient, rapid, and scalable information transfer. Artificial nanosystems explicitly engineered to probe and mimic these networks hold promise for fundamental studies on energy transfer alongside for the design of new architectures to store and convert information. Here, topological networks comprised of atomically precise, colloidal quantum wells are presented. The experiment highlights structural properties and establishes design strategies for preparing controlled hierarchies of low-dimensional, quantum confined materials distinguished by a high degree of organizational complexity. The discussion addresses the findings in the context of understanding and controlling some properties of atomically precise nanosystems in the limit of jammed, frustrated environments. |
Thursday, March 7, 2019 4:42PM - 4:54PM |
V21.00010: Metasurfaces to control the quantum dynamics of color centers in hexagonal boron nitride Pankaj Jha, Ghazaleh Kafaie Shirmanesh, Hamidreza Akbari, Arun Nagpal, Benjamin Vest, Cora Went, Wei-Hsiang Lin, Ruzan Sokhoyan, Harry Atwater Photonic metasurfaces have revolutionized optical designs by enabling the realization of virtually flat optics via the replacement of bulky optical components with ultrathin planar elements, which possess ease-of-fabrication advantages. However, majority of the application-oriented research in this field has been limited to classical regime and it remains an open question if these metasurfaces can be used for single-photon applications. |
Thursday, March 7, 2019 4:54PM - 5:06PM |
V21.00011: Effects of Nanostructured Plasmonic Environment on Electrochromic Polymer Switching Mohammad Shahabuddin, Carl E Bonner, Natalia Noginova Strong modification of local environment associated with plasmonic nanostructures provides possibilities to control various processes, including charge transfer processes and chemical reactions. In this work, we explore the opportunities to enhance electrochromic polymer performance using plasmonic metasurfaces, and study the origin of this enhancement. Electrochromic polyaniline (PANI) films deposited onto gold metasurfaces demonstrate non-monotonnous coloration behavior at low voltages, step-like color-change and much faster saturation in color with the increase in voltage in comparison with polyaniline films deposited on flat gold. The additional small voltage peak in the cyclic voltammogram in nanomesh/PANI cell and the asymmetric and nonlinear I-V characteristics of the sandwich nanomesh/PANI/flat gold structure indicate a possible formation of Schottky-like interface between polyaniline and nanostructured gold, whereas the Ohmic contact is observed for the flat gold-PANI system. The results are discussed in terms of the modified work-function of nanostructured gold, interface charging and threshold-like charge transport. Possibility to engineer optical and charge transport properties of electrochromic materials via nanostructured interfaces can bring niche applications. |
Thursday, March 7, 2019 5:06PM - 5:18PM |
V21.00012: FRET Enhancement using Surface Plasmon Modes on Gold Nanogratings Jennifer Steele, Chae Ramnarace, William R Farner The plasmonic properties of structured metal surfaces can be engineered to enhance the output of nearby quantum emitters through the manipulation of the local density of optical states (LDOS). Although metal enhanced fluorescence (MEF) has been well understood for decades, the influence of plasmonic modes in Förster resonance energy transfer (FRET) is still a debated issue. Gold nanogratings provide a unique plasmonic substrate to study the effects of altering the LDOS on FRET efficiencies. Gratings support narrow plasmon resonances at a range of wavelengths, allowing for the comparison of FRET efficiencies by increasing the LDOS at donor and acceptor emission wavelengths on a single substrate. In this work, the increase in efficiency was found to be greatest when the surface plasmon modes overlapped the acceptor emission spectrum. Furthering the understanding of the application of MEF to FRET will aid developing methods for the enhancement of FRET, expanding its use in biological systems, photosynthesis, and photovoltaic devices. |
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