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Murphey CGE, Park JS, Kim S, Cahoon JF. Epitaxially Grown Silicon Nanowires with a Gold Molecular Adhesion Layer for Core/Shell Structures with Compact Mie and Plasmon Resonances. ACS NANO 2023; 17:21739-21748. [PMID: 37890020 DOI: 10.1021/acsnano.3c07157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/29/2023]
Abstract
Noble-metal plasmonic nanostructures have attracted much attention because they can support deep-subwavelength optical resonances, yet their performance tends to be limited by high Ohmic absorption losses. In comparison, high-index dielectric materials can support low-loss optical resonances but do not tend to yield the same subwavelength optical confinement. Here, we combine these two approaches and examine the dielectric-plasmonic resonances in dielectric/metal core/shell nanowires. Si nanowires were grown epitaxially from (111) substrates, and direct deposition of Au on these structures by physical vapor deposition yielded nonconformal Au islands. However, by introduction of a molecular adhesion layer prior to deposition, cylindrical Si/Au core/shell nanostructures with conformal metal shells were successfully fabricated. Examining these structures as optical cavities using both optical simulations and experimental extinction measurements, we found that the structures support Mie resonances with quality factors enhanced up to ∼30 times compared with pure dielectric structures and plasmon resonances with optical confinement enhanced up to ∼5 times compared with pure metallic structures. Interestingly, extinction spectra of both Mie and plasmon resonances yield Fano line shapes, whose manifestation can be attributed to the combination of high quality factor resonances, Mie-plasmon coupling, and phase delay of the background optical field. This work demonstrates a bottom-up synthetic method for the production of freestanding, cylindrically symmetric semiconductor/metal core/shell nanowires that enables the efficient trapping of light on deep-subwavelength length scales for varied applications in photonics and optoelectronics.
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Affiliation(s)
- Corban G E Murphey
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Jin-Sung Park
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Seokhyoung Kim
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - James F Cahoon
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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2
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Grain N, Kim S. Insight into refractive index modulation as route to enhanced light coupling in semiconductor nanowires. OPTICS LETTERS 2023; 48:227-230. [PMID: 36638424 DOI: 10.1364/ol.478419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
Recent developments in chemical processes to prepare single-crystalline nanowire (NW) superlattices (SLs) have discovered a range of unique nanophotonic properties. In particular, diameter-modulated silicon NW geometric SLs (GSLs) have shown their ability to produce complex interference effects through which enhanced light manipulation is achieved. Here, we re-imagine the origin of the complex interference effects occurring in shallow-modulated GSLs and present a refractive index modulation as a key deciding factor. We introduce the design of a NW refractive index SL (ISL), a hypothetical uniform-diameter NW in which the refractive index is periodically modulated, and explain the coupling effect between Mie resonance and bound guided state. We apply the ISL concept to other NW SL systems and suggest potential routes to bring substantial enhancements in lasing activities.
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3
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Kim YB, Cho JW, Lee YJ, Bae D, Kim SK. High-index-contrast photonic structures: a versatile platform for photon manipulation. LIGHT, SCIENCE & APPLICATIONS 2022; 11:316. [PMID: 36316304 PMCID: PMC9622741 DOI: 10.1038/s41377-022-01021-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 10/13/2022] [Accepted: 10/14/2022] [Indexed: 06/16/2023]
Abstract
In optics, the refractive index of a material and its spatial distribution determine the characteristics of light propagation. Therefore, exploring both low- and high-index materials/structures is an important consideration in this regard. Hollow cavities, which are defined as low-index bases, exhibit a variety of unusual or even unexplored optical characteristics and are used in numerous functionalities including diffraction gratings, localised optical antennas and low-loss resonators. In this report, we discuss the fabrication of hollow cavities of various sizes (0.2-5 μm in diameter) that are supported by conformal dielectric/metal shells, as well as their specific applications in the ultraviolet (photodetectors), visible (light-emitting diodes, solar cells and metalenses), near-infrared (thermophotovoltaics) and mid-infrared (radiative coolers) regions. Our findings demonstrate that hollow cavities tailored to specific spectra and applications can serve as versatile optical platforms to address the limitations of current optoelectronic devices. Furthermore, hollow cavity embedded structures are highly elastic and can minimise the thermal stress caused by high temperatures. As such, future applications will likely include high-temperature devices such as thermophotovoltaics and concentrator photovoltaics.
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Affiliation(s)
- Young-Bin Kim
- Department of Applied Physics, Kyung Hee University, Yongin, Gyeonggi-do, 17104, Republic of Korea
| | - Jin-Woo Cho
- Department of Applied Physics, Kyung Hee University, Yongin, Gyeonggi-do, 17104, Republic of Korea
| | - Yun-Jo Lee
- Department of Applied Physics, Kyung Hee University, Yongin, Gyeonggi-do, 17104, Republic of Korea
| | - Dukkyu Bae
- Hexa Solution Co., Ltd, Suwon, Gyeonggi-do, 16229, Republic of Korea
| | - Sun-Kyung Kim
- Department of Applied Physics, Kyung Hee University, Yongin, Gyeonggi-do, 17104, Republic of Korea.
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4
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Kim MW, Park SW, Park KT, Min BJ, Ku JH, Ko JY, Choi JS, No YS. All-Graphene-Contact Electrically Pumped On-Demand Transferrable Nanowire Source. NANO LETTERS 2022; 22:1316-1323. [PMID: 35049311 DOI: 10.1021/acs.nanolett.1c04622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
On-demand NW light sources in a photonic integrated circuit (PIC) have faced several practical challenges. Here, we report on an all-graphene-contact, electrically pumped, on-demand transferrable NW source that is fabricated by implementing an all-graphene-contact approach in combination with a highly accurate microtransfer printing technique. A vertically p-i-n-doped top-down-fabricated semiconductor NW with optical gain structures is electrically pumped through the patterned multilayered graphene contacts. Electroluminescence (EL) spectroscopy results reveal that the electrically driven NW device exhibits strong EL emission between the contacts and displays waveguiding properties. Further, a single NW device is precisely integrated into an existing photonic waveguide to perform light coupling and waveguiding experiments. Three-dimensional numerical simulation results show a good agreement with experimental observations. We believe that our all-graphene-contact approach is readily applicable to various micro/nanostructures and devices, which facilitates stable electrical operation and thus extends their practical applicability in compact integrated circuits.
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Affiliation(s)
- Min-Woo Kim
- Department of Physics, Konkuk University, Seoul 05029, Republic of Korea
| | - Sun-Wook Park
- Department of Physics, Konkuk University, Seoul 05029, Republic of Korea
| | - Kyong-Tae Park
- Department of Physics, Konkuk University, Seoul 05029, Republic of Korea
| | - Byung-Ju Min
- Department of Physics, Konkuk University, Seoul 05029, Republic of Korea
| | - Ja-Hyun Ku
- Department of Physics, Konkuk University, Seoul 05029, Republic of Korea
| | - Jin-Yong Ko
- Department of Physics, Konkuk University, Seoul 05029, Republic of Korea
| | - Jin Sik Choi
- Department of Physics, Konkuk University, Seoul 05029, Republic of Korea
| | - You-Shin No
- Department of Physics, Konkuk University, Seoul 05029, Republic of Korea
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5
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The Impact of Engineered Silver Nanomaterials on the Immune System. NANOMATERIALS 2020; 10:nano10050967. [PMID: 32443602 PMCID: PMC7712063 DOI: 10.3390/nano10050967] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 01/07/2023]
Abstract
Over the last decades there has been a tremendous volume of research efforts focused on engineering silver-based (nano)materials. The interest in silver has been mostly driven by the element capacity to kill pathogenic bacteria. In this context, the main area of application has been medical devices that are at significant risk of becoming colonized by bacteria and subsequently infected. However, silver nanomaterials have been incorporated in a number of other commercial products which may or may not benefit from antibacterial protection. The rapid expansion of such products raises important questions about a possible adverse influence on human health. This review focuses on examining currently available literature and summarizing the current state of knowledge of the impact of silver (nano)materials on the immune system. The review also looks at various surface modification strategies used to generate silver-based nanomaterials and the immunomodulatory potential of these materials. It also highlights the immune response triggered by various silver-coated implantable devices and provides guidance and perspective towards engineering silver nanomaterials for modulating immunological consequences.
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6
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Yang X, Shan Z, Luo Z, Hu X, Liu H, Liu Q, Zhang Y, Zhang X, Shoaib M, Qu J, Yi X, Wang X, Zhu X, Liu Y, Liao L, Wang X, Chen S, Pan A. An Electrically Controlled Wavelength-Tunable Nanoribbon Laser. ACS NANO 2020; 14:3397-3404. [PMID: 32052962 DOI: 10.1021/acsnano.9b09301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nanoscale laser sources with downscaled device footprint, high energy efficiency, and high operation speed are pivotal for a wide array of optoelectronic and nanophotonic applications ranging from on-chip interconnects, nanospectroscopy, and sensing to optical communication. The capability of on-demand lasing output with reversible and continuous wavelength tunability over a broad spectral range enables key functionalities in wavelength-division multiplexing and finely controlled light-matter interaction, which remains an important subject under intense research. In this study, we demonstrate an electrically controlled wavelength-tunable laser based on a CdS nanoribbon (NR) structure. Typical "S"-shaped characteristics of pump power dependence were observed for dominant lasing lines, with concomitant line width narrowing. By applying an increased bias voltage across the NR device, the lasing resonance exhibits a continuous tuning from 510 to 520 nm for a bias field in the range 0-15.4 kV/cm. Systematic bias-dependent absorption and time-resolved photoluminescence (PL) measurements were performed, revealing a red-shifted band edge of gain medium and prolonged PL lifetime with increased electric field over the device. Both current-induced thermal reduction of the band gap and the Franz-Keldysh effect were identified to account for the modification of the lasing profile, with the former factor playing the leading role. Furthermore, dynamical switching of NR lasing was successfully demonstrated, yielding a modulation ratio up to ∼21 dB. The electrically tuned wavelength-reversible CdS NR laser in this work, therefore, presents an important step toward color-selective coherent emitters for future chip-based nanophotonic and optoelectronic circuitry.
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Affiliation(s)
- Xin Yang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Zhengping Shan
- Computer and Information Engineering College, Central South University of Forestry and Technology, Changsha 410004, Hunan, People's Republic of China
| | - Ziyu Luo
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Xuelu Hu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Huawei Liu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Qingbo Liu
- College of Physics and Electronics, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Yushuang Zhang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Xuehong Zhang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Muhammad Shoaib
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Junyu Qu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Xiao Yi
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Xiao Wang
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Xiaoli Zhu
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Yuan Liu
- College of Physics and Electronics, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Lei Liao
- College of Physics and Electronics, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Xingjun Wang
- State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, People's Republic of China
| | - Shula Chen
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
| | - Anlian Pan
- Key Laboratory for Micro-Nano Physics and Technology of Hunan Province, State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, People's Republic of China
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7
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Wendisch F, Abazari M, Mahdavi H, Rey M, Vogel N, Musso M, Diwald O, Bourret GR. Morphology-Graded Silicon Nanowire Arrays via Chemical Etching: Engineering Optical Properties at the Nanoscale and Macroscale. ACS APPLIED MATERIALS & INTERFACES 2020; 12:13140-13147. [PMID: 32129591 PMCID: PMC7082793 DOI: 10.1021/acsami.9b21466] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We report on a quick, simple, and cost-effective solution-phase approach to prepare centimeter-sized morphology-graded vertically aligned Si nanowire arrays. Gradients in the nanowire diameter and shape are encoded through the macroscale substrate via a "dip-etching" approach, where the substrate is removed from a KOH etching solution at a constant rate, while morphological control at the nanowire level is achieved via sequential metal-assisted chemical etching and KOH etching steps. This combined approach provides control over light absorption and reflection within the nanowire arrays at both the macroscale and nanoscale, as shown by UV-vis spectroscopy and numerical three-dimensional finite-difference time-domain simulations. Macroscale morphology gradients yield arrays with gradually changing optical properties. Nanoscale morphology control is demonstrated by synthesizing arrays of bisegmented nanowires, where the nanowires are composed of two distinct segments with independently controlled lengths and diameters. Such nanowires are important to tailor light-matter interactions in functional devices, especially by maximizing light absorption at specific wavelengths and locations within the nanowires.
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Affiliation(s)
- Fedja
J. Wendisch
- Department
of Chemistry and Physics of Materials, University
of Salzburg, Jakob Haringer Strasse 2A, A-5020 Salzburg, Austria
| | - Mehri Abazari
- Department
of Chemistry and Physics of Materials, University
of Salzburg, Jakob Haringer Strasse 2A, A-5020 Salzburg, Austria
- School
of Chemistry, College of Science, University
of Tehran, 14155-6455 Tehran, Iran
| | - Hossein Mahdavi
- School
of Chemistry, College of Science, University
of Tehran, 14155-6455 Tehran, Iran
| | - Marcel Rey
- Institute
of Particle Technology, Friedrich-Alexander
University Erlangen-Nürnberg, Cauerstrasse 4, 91058 Erlangen, Germany
| | - Nicolas Vogel
- Institute
of Particle Technology, Friedrich-Alexander
University Erlangen-Nürnberg, Cauerstrasse 4, 91058 Erlangen, Germany
| | - Maurizio Musso
- Department
of Chemistry and Physics of Materials, University
of Salzburg, Jakob Haringer Strasse 2A, A-5020 Salzburg, Austria
| | - Oliver Diwald
- Department
of Chemistry and Physics of Materials, University
of Salzburg, Jakob Haringer Strasse 2A, A-5020 Salzburg, Austria
| | - Gilles R. Bourret
- Department
of Chemistry and Physics of Materials, University
of Salzburg, Jakob Haringer Strasse 2A, A-5020 Salzburg, Austria
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8
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Zhang Q, Zhang D, Gu L, Tsui KH, Poddar S, Fu Y, Shu L, Fan Z. Three-Dimensional Perovskite Nanophotonic Wire Array-Based Light-Emitting Diodes with Significantly Improved Efficiency and Stability. ACS NANO 2020; 14:1577-1585. [PMID: 31944666 DOI: 10.1021/acsnano.9b06663] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Hybrid perovskites have emerged as promising candidates for highly efficient light-emitting diodes in the past few years due to their excellent crystallinity, high color purity, wide-range bandgap tunability, and solution processability. However, the reported device external quantum efficiency has not reached the level on par with that of conventional inorganic and organic light-emitting diodes. Moreover, device stability still needs substantial improvement. In this work, we demonstrate the fabrication of perovskite nanophotonic wire array-based light-emitting diodes with a capillary-effect-assisted template method. Compared with the planar control device, the nanostructured device demonstrates 45% improvement of external quantum efficiency from 11% to 16% owing to substantial enhancement on device light extraction efficiency verified by optical modeling. Intriguingly, it is also discovered that the nanostructured device possesses 3.89 times lifetime compared to the planar control device, due to effective template passivation. The results here have clearly shown that with a proper photonic device structure design, both the device performance and lifetime can be significantly improved.
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Affiliation(s)
- Qianpeng Zhang
- Department of Electronic & Computer Engineering , The Hong Kong University of Science and Technology , Clear Water Bay , Hong Kong SAR , China
| | - Daquan Zhang
- Department of Electronic & Computer Engineering , The Hong Kong University of Science and Technology , Clear Water Bay , Hong Kong SAR , China
- HKUST-Shenzhen Research Institute , No. 9 Yuexing first RD, South Area, Hi-tech Park, Nanshan , Shenzhen 518057 , China
| | - Leilei Gu
- Department of Electronic & Computer Engineering , The Hong Kong University of Science and Technology , Clear Water Bay , Hong Kong SAR , China
- HKUST-Shenzhen Research Institute , No. 9 Yuexing first RD, South Area, Hi-tech Park, Nanshan , Shenzhen 518057 , China
| | - Kwong-Hoi Tsui
- Department of Electronic & Computer Engineering , The Hong Kong University of Science and Technology , Clear Water Bay , Hong Kong SAR , China
| | - Swapnadeep Poddar
- Department of Electronic & Computer Engineering , The Hong Kong University of Science and Technology , Clear Water Bay , Hong Kong SAR , China
| | - Yu Fu
- Department of Electronic & Computer Engineering , The Hong Kong University of Science and Technology , Clear Water Bay , Hong Kong SAR , China
- HKUST-Shenzhen Research Institute , No. 9 Yuexing first RD, South Area, Hi-tech Park, Nanshan , Shenzhen 518057 , China
| | - Lei Shu
- Department of Electronic & Computer Engineering , The Hong Kong University of Science and Technology , Clear Water Bay , Hong Kong SAR , China
| | - Zhiyong Fan
- Department of Electronic & Computer Engineering , The Hong Kong University of Science and Technology , Clear Water Bay , Hong Kong SAR , China
- HKUST-Shenzhen Research Institute , No. 9 Yuexing first RD, South Area, Hi-tech Park, Nanshan , Shenzhen 518057 , China
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9
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Kim S, Cahoon JF. Geometric Nanophotonics: Light Management in Single Nanowires through Morphology. Acc Chem Res 2019; 52:3511-3520. [PMID: 31799833 DOI: 10.1021/acs.accounts.9b00515] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Comprehensive control of light-matter interactions at the nanoscale is increasingly important for the development of miniaturized light-based technologies that have applications ranging from information processing to sensing. Control of light in nanoscale structures-the realm of nanophotonics-requires precise control of geometry on a few-nanometer length scale. From a chemist's perspective, bottom-up growth of nanoscale materials from chemical precursors offers a unique opportunity to design structures atom-by-atom that exhibit desired properties. In this Account, we describe our efforts to create chemically and morphologically precise Si nanowires (NWs) with designed nanophotonic properties using a vapor-liquid-solid (VLS) growth process. A synthetic technique termed "Encoded Nanowire Growth and Appearance through VLS and Etching" (ENGRAVE) combines optimized VLS growth, dopant modulation, and dopant-dependent wet-chemical etching to produce NWs with precisely designed diameter modulations, yielding lithographic-like morphological control that can vary from sinusoids to fractals. The ENGRAVE NWs thus provide a versatile playground for coupling, trapping, and directing light in a nanoscale geometry. Previously, the nanophotonic functionality of NWs primarily relied on uniform-diameter structures that exhibit Mie scattering resonances and longitudinally oriented guided modes, two key photonic properties that typically cannot be utilized simultaneously due to their orthogonality. However, when the NW diameter is controllably modulated along the longitudinal axis on a scale comparable to the wavelength of light-a geometry we term a geometric superlattice (GSL)-we found that NWs can exhibit a much richer and tunable set of nanophotonic properties, as described herein. To understand these unique properties, we first summarize the basic optical properties of uniform-diameter NWs using Mie scattering theory and dispersion relations, and we describe both conventional and relatively new microscopy methods that experimentally probe the optical properties of single NWs. Next, delving into the properties of NW GSLs, we summarize their ability to couple a Mie resonance with a guided mode at a select wavevector (or wavelength) dictated by their geometric pitch. The coupling forms a bound guided state (BGS) with a standing wave profile, which allows a NW GSL to serve as a spectrally selective light coupler and to act as optical switch or sensor. We also summarize the capacity of a GSL to trap light by serving as an ultrahigh (theoretically infinite) quality factor optical cavity with an optical bound state in the continuum (BIC), in which destructive interference prevents coupling to and from the far field. Finally, we discuss a future research outlook for using ENGRAVE NWs for nanoscale light control. For instance, we highlight research avenues that could yield light-emitting devices by interfacing a NW-based BIC with emissive materials such as quantum dots, 2D materials, and hybrid perovskite. We also discuss the design of photonic band gaps, generation of high-harmonics with quasi-BIC structures, and the possibility for undiscovered nanophotonic properties and phenomena through more complex ENGRAVE geometric designs.
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Affiliation(s)
- Seokhyoung Kim
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - James F. Cahoon
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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10
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Lee HC, Lee SJ, Kim J, Kim KH, Park JS, Hwang MS, Lee JM, Jeong KY, Park HG. Unique Scattering Properties of Silicon Nanowires Embedded with Porous Segments. ACS APPLIED MATERIALS & INTERFACES 2019; 11:21094-21099. [PMID: 31099238 DOI: 10.1021/acsami.9b04680] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The development of advanced imaging tools is important for the investigation of the fundamental properties of nanostructures composed of single or multiple nanomaterials. However, complicated preparation processes and irreversible alterations of the samples to be examined are inevitable in most current imaging techniques. In this work, we developed a simple method based on polarization-resolved light scattering measurements to characterize the structural and optical properties of complex nanomaterials. In particular, we examined a single Si nanowire embedded with porous Si segments, in which the porous Si could not be easily distinguished from solid Si by scanning electron microscopy. The dark-field optical images and polarization-resolved scattering spectra showed unique optical features of porous and solid Si. In particular, the porosity, diameter, and number of porous Si segments in the single Si nanowire were identified from the scattering measurements. In addition, we performed systematic optical simulations based on the effective medium model in individual porous and solid Si nanowires. A good agreement between the simulation and measurement results enabled the estimation of the structural parameters of the nanowires, such as diameter and porosity. We believe that our method will be useful for analyzing the structural and optical properties of nanomaterials prior to using complicated and uneconomical imaging tools.
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Affiliation(s)
| | | | | | - Kyoung-Ho Kim
- Department of Physics , Chungbuk National University , Cheongju 28644 , Korea
| | | | | | | | | | - Hong-Gyu Park
- Center for Molecular Spectroscopy and Dynamics , Institute for Basic Science , Seoul 02841 , Korea
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11
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Kim S, Kim KH, Cahoon JF. Optical Bound States in the Continuum with Nanowire Geometric Superlattices. PHYSICAL REVIEW LETTERS 2019; 122:187402. [PMID: 31144898 DOI: 10.1103/physrevlett.122.187402] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Indexed: 06/09/2023]
Abstract
Perfect trapping of light in a subwavelength cavity is a key goal in nanophotonics. Perfect trapping has been realized with optical bound states in the continuum (BIC) in waveguide arrays and photonic crystals; yet the formal requirement of infinite periodicity has limited the experimental realization to structures with macroscopic planar dimensions. We characterize BICs in a silicon nanowire (NW) geometric superlattice (GSL) that exhibits one-dimensional periodicity in a compact cylindrical geometry with a subwavelength diameter. We analyze the scattering behavior of NW GSLs by formulating temporal coupled mode theory to include Lorenz-Mie scattering, and we show that GSL-based BICs can trap electromagnetic energy for an infinite lifetime and exist over a broad range of geometric parameters. Using synthesized NW GSLs tens of microns in length and with variable pitch, we demonstrate the progressive spectral shift and disappearance of Fano resonances in experimental single-NW extinction spectra as a manifestation of BIC GSL modes.
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Affiliation(s)
- Seokhyoung Kim
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
| | - Kyoung-Ho Kim
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
- Department of Physics, Chungbuk National University, Cheongju 28644, Republic of Korea
| | - James F Cahoon
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, USA
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