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Ma Y, Hu J, Li W, Yang Z. Angle-Insensitive Ultrathin Broadband Visible Absorber Based on Dielectric-Semiconductor-Lossy Metal Film Stacks. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:2726. [PMID: 37836367 PMCID: PMC10574125 DOI: 10.3390/nano13192726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 09/28/2023] [Accepted: 10/06/2023] [Indexed: 10/15/2023]
Abstract
Ultrathin broadband absorbers with high efficiency, wide angular tolerance, and low fabrication cost are in demand for various applications. Here, we present an angle-insensitive ultrathin (<150 nm) broadband absorber with an average 96.88% (experiment) absorptivity in the whole visible range by utilizing a simple dielectric-semiconductor-lossy metal triple-layer film structure. The excellent broadband absorption performance of the device results from the combined action of the enhanced absorptions in the semiconductor and lossy metal layers exploiting strong interference effects and can be maintained over a wide viewing angle up to ±60°. Benefiting from the lossy metal providing additional absorption, our design reduces the requirement for the semiconductor's material dispersion and has great flexibility in the material selection of the metal layer. Additionally, the lithography-free nature of the proposed broadband visible absorber provides a high-throughput fabrication convenience, thus holding great potential for its large-area applications in various fields.
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Affiliation(s)
- Yuanchen Ma
- State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; (Y.M.); (J.H.); (W.L.)
- School of Artificial Intelligence, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Junhao Hu
- State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; (Y.M.); (J.H.); (W.L.)
- School of Artificial Intelligence, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Wenfeng Li
- State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; (Y.M.); (J.H.); (W.L.)
- School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Zhengmei Yang
- State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; (Y.M.); (J.H.); (W.L.)
- School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China
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2
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Sun J, Nguyen DH, Liu J, Lo C, Ma Y, Chen Y, Yi J, Huang J, Giap H, Nguyen HYT, Liao C, Lin M, Lai C. On-Chip Monolithically Integrated Ultraviolet Low-Threshold Plasmonic Metal-Semiconductor Heterojunction Nanolasers. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2301493. [PMID: 37559172 PMCID: PMC10558691 DOI: 10.1002/advs.202301493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 07/16/2023] [Indexed: 08/11/2023]
Abstract
The metal-semiconductor heterojunction is imperative for the realization of electrically driven nanolasers for chip-level platforms. Progress in developing such nanolasers has hitherto rarely been realized, however, because of their complexity in heterojunction fabrication and the need to use noble metals that are incompatible with microelectronic manufacturing. Most plasmonic nanolasers lase either above a high threshold (101 -103 MW cm-2 ) or at a cryogenic temperature, and lasing is possible only after they are removed from the substrate to avoid the large ohmic loss and the low modal reflectivity, making monolithic fabrication impossible. Here, for the first time, record-low-threshold, room-temperature ultraviolet (UV) lasing of plasmon-coupled core-shell nanowires that are directly grown on silicon is demonstrated. The naturally formed core-shell metal-semiconductor heterostructure of the nanowires leads to a 100-fold improvement in growth density over previous results. This unprecedentedly high nanowire density creates intense plasmonic resonance, which is outcoupled to the resonant Fabry-Pérot microcavity. By boosting the emission strength by a factor of 100, the hybrid photonic-plasmonic system successfully facilitates a record-low laser threshold of 12 kW cm-2 with a spontaneous emission coupling factor as high as ≈0.32 in the 340-360 nm range. Such architecture is simple and cost-competitive for future UV sources in silicon integration.
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Affiliation(s)
- Jia‐Yuan Sun
- Department of PhysicsNational Dong Hwa UniversityHualien974301Taiwan
| | - Duc Huy Nguyen
- Department of PhysicsNational Dong Hwa UniversityHualien974301Taiwan
| | - Jia‐Ming Liu
- Department of Electrical and Computer EngineeringUniversity of CaliforniaLos AngelesCA90095USA
- Institute of PhotonicsNational Yang Ming Chiao Tung UniversityTainan711010Taiwan
- Institute of OptoelectronicsNational Chung Hsing UniversityTaichung402202Taiwan
| | - Chia‐Yao Lo
- Department of Optoelectronics and Materials TechnologyNational Taiwan Ocean UniversityKeelung202301Taiwan
| | - Yuan‐Ron Ma
- Department of PhysicsNational Dong Hwa UniversityHualien974301Taiwan
| | - Yi‐Jia Chen
- Department of Materials Science and EngineeringNational Dong Hwa UniversityHualien974301Taiwan
| | - Jui‐Yun Yi
- Department of Electrical EngineeringNational Kaohsiung Normal UniversityKaohsiung824004Taiwan
| | - Jian‐Zhi Huang
- Department of Opto‐Electronic EngineeringNational Dong Hwa UniversityHualien974301Taiwan
| | - Hien Giap
- Department of PhysicsNational Dong Hwa UniversityHualien974301Taiwan
| | | | - Chun‐Da Liao
- R&D CenterTaiwan Semiconductor Manufacturing CompanyHsinchu300091Taiwan
| | - Ming‐Yi Lin
- Department of DermatologyNational Taiwan University Hospital and College of MedicineNational Taiwan UniversityTaipei100229Taiwan
| | - Chien‐Chih Lai
- Department of PhysicsNational Dong Hwa UniversityHualien974301Taiwan
- Department of Opto‐Electronic EngineeringNational Dong Hwa UniversityHualien974301Taiwan
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Xie Q, Feng H, Wu S, Liu X, Xu Z. Omnidirectional, thin metasurface exhibiting selective absorption for un-polarized broadband incidence. OPTICS EXPRESS 2022; 30:28737-28744. [PMID: 36299062 DOI: 10.1364/oe.467446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 07/06/2022] [Indexed: 06/16/2023]
Abstract
Thin devices with large areas have strong and omnidirectional absorption over a wide bandwidth and are in demand for applications such as energy harvesting, structural color, and vehicle LiDAR (laser detection and ranging). Despite persistent efforts in the design and fabrication of such devices, the simultaneous realization of all these desired properties remains a challenge. In this study, a 190-nm-thick metasurface with an area of 3 cm2, incorporating dielectric cylinder arrays, a chromium layer, a silicon nitride (SiNx) layer, and an aluminum layer is theoretically and experimentally demonstrated. The developed device achieves an average absorptivity of ∼99% (97% in the experiment) in the entire visible spectrum 400-700 nm. Moreover, it exhibits strong absorption over a wide range of incident angles (∼91% and 90% at 60° in the calculation and experiment, respectively). Importantly, the feasibility of applying the developed metasurface absorber to solar thermophotovoltaics and vehicle LiDAR (laser detection and ranging) has been explored. Moreover, the photoresist can be replaced by other glues and easily scaled up to a large area using the roll-to-roll nanoimprinting process. With the excellent spectral properties and performance, this device is promising for large-area applications.
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Buranasiri P, Plaipichit S, Puttharugsa C, Wicharn S. Hybrid nanowire-hyperbolic metamaterial based broadband absorber for the visible and near-infrared regions. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2021.109701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Naziul Haque AKM, Ahmed T, Baten MZ. In-plane directionality control of strongly localized resonant modes of light in disordered arrays of dielectric scatterers. OPTICS EXPRESS 2021; 29:39227-39240. [PMID: 34809291 DOI: 10.1364/oe.443103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/30/2021] [Indexed: 06/13/2023]
Abstract
In this work we propose and analyze techniques of in-plane directionality control of strongly localized resonant modes of light in random arrays of dielectric scatterers. Based on reported diameters and areal densities of epitaxially grown self-organized nanowires, two-dimensional (2D) arrays of dielectric scatterers have been analyzed where randomness is gradually increased along a preferred direction of directionality enhancement. In view of the multiple-scattering mediated wave dynamics and directionality enhancement of light in such arrays, a more conveniently realizable, practical structure is proposed where a 2D periodic array is juxtaposed with a uniform, random scattering medium. Far- and near-field emission characteristics of such arrays show that in spite of the utter lack of periodicity in the disordered regime of the structure, directionality of the high-Q resonant modes is modified such that on average more than 70% of the output power is emitted along the pre-defined direction of preference. Such directionality enhancement and strong localization are nonexistent when the 2D periodic array is replaced with a one-dimensional Bragg reflector, thereby confirming the governing role of in-plane multiple scattering in the process. The techniques presented herein offer novel means of realizing not only directionality tunable edge-emitting random lasers but also numerous other disordered media based photonic structures and systems with higher degrees of control and tunability.
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Chervinskii S, Issah I, Lahikainen M, Rashed AR, Kuntze K, Priimagi A, Caglayan H. Humidity- and Temperature-Tunable Metal-Hydrogel-Metal Reflective Filters. ACS APPLIED MATERIALS & INTERFACES 2021; 13:50564-50572. [PMID: 34643385 PMCID: PMC8554756 DOI: 10.1021/acsami.1c15616] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 10/04/2021] [Indexed: 06/01/2023]
Abstract
A tunable reflectance filter based on a metal-hydrogel-metal structure responsive to humidity and temperature is reported. The filter employs a poly(N-isopropylacrylamide)-acrylamidobenzophenone (PNIPAm-BP) hydrogel as an insulator layer in the metal-insulator-metal (MIM) assembly. The optical resonance of the structure is tunable by water immersion across the visible and near-infrared range. Swelling/deswelling and the volume phase transition of the hydrogel allow continuous reversible humidity- and/or temperature-induced tuning of the optical resonance. This work paves the way toward low-cost large-area fabrication of actively tunable reversible photonic devices.
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Wicharn S, Buranasiri P. Hybrid nanowires for phase-matching of third-harmonic generation in hyperbolic metamaterial. APPLIED OPTICS 2021; 60:8744-8755. [PMID: 34613100 DOI: 10.1364/ao.427283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 09/05/2021] [Indexed: 06/13/2023]
Abstract
We propose a phase-matching technique for third-harmonic generation, called hyperbolic phase matching, that possibly can be achieved by optimal designing and engineering dispersion of hybrid-nanowire hyperbolic metamaterial. We demonstrate phase-matched conditions for two different third-harmonic interacting configurations, which can be created at two optimal incident angles of the pump field. Moreover, each composed hybrid nanowire can enhance third-harmonic generation by using strong field confinement along the metal/dielectric interface due to plasmonic resonance. Finally, conversion efficiencies of transmitted and reflected third-harmonic pulses as a function of incident angle and input pulse intensity are examined by numerical integration of nonlinear birefringent coupled-mode equations. The numerical results validate the idea that, using a combination of phase-matched conditions and pump field confinement, we can achieve a dramatic enhancement of conversion efficiencies of third-harmonic generation.
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Wu D, Chen J. Broadening Bandwidths of Few-Layer Absorbers by Superimposing Two High-Loss Resonators. NANOSCALE RESEARCH LETTERS 2021; 16:26. [PMID: 33566218 PMCID: PMC7876209 DOI: 10.1186/s11671-020-03471-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 12/29/2020] [Indexed: 06/12/2023]
Abstract
Efficient broadband absorption of solar radiation is desired for sea water desalination, icephobicity and other renewable energy applications. We propose an idea of superimposing two high-loss resonances to broaden bandwidths of a few-layer absorber, which is made of dielectric/ metal/dielectric/ metal layers. Both the simulation and experiment show that the structure has an averaged absorption efficiency higher than 97% at wavelengths ranging from 350 to 1200 nm. The bandwidth of the absorption larger than 90% is up to 1000 nm (410-1410 nm), which is greater than that (≤ 750 nm) of previous MIM planar absorbers. Especially, the average absorption from 350 to 1000 nm is kept above 90% at an incidence angle as high as 65°, meanwhile still maintained above 80% even at an incident angle of 75°. The performance of angular insensitivity is much better than that of previous few-layer solar absorbers. The flexible 1D nonoble metasurface absorbers are fabricated in a single evaporation step. Under the illumination of a halogen lamp of P = 1.2 kW/m2, the flexible metasurface increases its surface temperature by 25.1 K from room temperature. Further experiments demonstrate that the heat localization rapidly melts the accumulated ice. Our illumination intensity (P = 1.2 kW/m2) is only half of that (P = 2.4 kW/m2) in previous solar anti-ice studies based on gold/TiO2 particle metasurfaces, indicating that our metasurface is more advantageous topractical applications. Our results illustrate an effective pathway toward the broadband metasurface absorbers with the attractive properties of mechanical flexibility, low cost of the no-noble metals, and large-area fabrications, which have promising prospects in the applications of solar heat utilization.
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Affiliation(s)
- Dong Wu
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, China
| | - Jianjun Chen
- State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, China.
- Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing, 100875, China.
- Peking University Yangtze Delta Institute of Optoelectronics, Nantong, 226010, Jiangsu, China.
- Frontiers Science Center for Nano-Optoelectronics & Collaborative Innovation Center of Quantum Matter, Peking University, Beijing, 100871, China.
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, 030006, Shanxi, China.
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Zhou J, Liu Z, Liu G, Pan P, Liu X, Tang C, Liu Z, Wang J. Ultra-broadband solar absorbers for high-efficiency thermophotovoltaics. OPTICS EXPRESS 2020; 28:36476-36486. [PMID: 33379740 DOI: 10.1364/oe.411918] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Accepted: 11/10/2020] [Indexed: 06/12/2023]
Abstract
Metamaterial absorbers have attracted great attention over the past few years and exhibited a promising prospect in solar energy harvesting and solar thermophotovoltaics (STPVs). In this work, we introduce a solar absorber scheme, which enables efficient solar irradiance harvesting, superb thermal robustness and high solar thermal energy conversion for STPV systems. The optimum structure demonstrates an average absorbance of 97.85% at the spectral region from 200 nm to 2980 nm, indicating the near-unity absorption in the main energy range of the solar radiance. The solar-thermal conversion efficiencies surpassing 90% are achieved over an ultra-wide temperature range (100-800 °C). Meanwhile, the analysis indicates that this metamaterial has strong tolerance for fabrication errors. By utilizing the simple two-dimensional (2D) titanium (Ti) gratings, this design is able to get beyond the limit of costly and sophisticated nanomanufacturing techniques. These impressive features can hold the system with wide applications in metamaterial and other optoelectronic devices.
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10
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Feng L, Huo P, Liang Y, Xu T. Photonic Metamaterial Absorbers: Morphology Engineering and Interdisciplinary Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1903787. [PMID: 31566259 DOI: 10.1002/adma.201903787] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/29/2019] [Indexed: 06/10/2023]
Abstract
Recent advances in nanofabrication technologies have spurred many breakthroughs in the field of photonic metamaterials that provide efficient ways of manipulating light-matter interaction at subwavelength scales. As one of the most important applications, photonic metamaterials can be used to implement novel optical absorbers. First the morphology engineering of various photonic metamaterial absorbers is discussed, which is highly associated with impendence matching conditions and resonance modes of the absorbers, thus directly determines their absorption efficiency, operational bandwidth, incident angle, and polarization dependence. Then, the recent achievements of various interdisciplinary applications based on photonic metamaterial absorbers, including structural color generation, ultrasensitive optical sensing, solar steam generation, and highly responsive photodetection, are reviewed. This report is expected to provide an overview and vision for the future development of photonic metamaterial absorbers and their applications in novel nanophotonic systems.
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Affiliation(s)
- Lei Feng
- National Laboratory of Solid-State Microstructures, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Pengcheng Huo
- National Laboratory of Solid-State Microstructures, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Yuzhang Liang
- National Laboratory of Solid-State Microstructures, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Ting Xu
- National Laboratory of Solid-State Microstructures, College of Engineering and Applied Sciences and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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Aalizadeh M, Khavasi A, Butun B, Ozbay E. Lithography-free, manganese-based ultrabroadband absorption through annealing-based deformation of thin layers into metal-air composites. OPTICS LETTERS 2019; 44:3598-3601. [PMID: 31305581 DOI: 10.1364/ol.44.003598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 06/19/2019] [Indexed: 06/10/2023]
Abstract
Fabrication, characterization, and analysis of an ultrabroadband lithography-free absorber is presented. An over 94% average absorption is experimentally achieved in the wavelength range of 450-1400 nm. This ultrabroadband absorption is obtained by a simple annealed trilayer metal-insulator-metal (MIM) configuration. The metal used in the structure is manganese (Mn), which also makes the structure cost-effective. It is shown that the structure retains its high absorption for TM polarization, up to 70 deg, and, for TE polarization, up to 50 deg. Moreover, the physical mechanism behind this broadband absorption is explained. Being both lithography-free and cost-effective, the structure is a perfect candidate for large-area and mass production purposes.
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12
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Ghobadi A, Hajian H, Soydan MC, Butun B, Ozbay E. Lithography-Free Planar Band-Pass Reflective Color Filter Using A Series Connection of Cavities. Sci Rep 2019; 9:290. [PMID: 30670767 PMCID: PMC6342952 DOI: 10.1038/s41598-018-36540-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 11/23/2018] [Indexed: 12/03/2022] Open
Abstract
In this article, a lithography-free multilayer based color filter is realized using a proper series connection of two cavities that shows relatively high efficiency, high color purity, and a wide view angle. The proposed structure is a metal-insulator-metal-insulator-semiconductor (MIMIS) design. To optimize the device performance, at the first step, transfer matrix method (TMM) modeling is utilized to find the right choices of materials for each layer. Simulations are carried out later on to optimize the geometries of the layers to obtain our desired colors. Finally, the optimized devices are fabricated and experimentally characterized to evaluate our modelling findings. The characterization results of the fabricated samples prove the successful formation of efficient and wide view angle color filters. Unlike previously reported FP based designs that act as a band-stop filter in reflection mode (absorbing a narrow frequency range and reflecting the rest of the spectrum), this design generates a specific color by reflecting a narrow spectral range and absorbing the rest of the spectrum. The findings of this work can be extended to other multilayer structures where an efficient connection of cavities in a tandem scheme can propose functionalities that cannot be realized with conventional FP resonators.
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Affiliation(s)
- Amir Ghobadi
- NANOTAM - Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey. .,Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800, Turkey.
| | - Hodjat Hajian
- NANOTAM - Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey
| | - Mahmut Can Soydan
- NANOTAM - Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.,Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800, Turkey
| | - Bayram Butun
- NANOTAM - Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey
| | - Ekmel Ozbay
- NANOTAM - Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey. .,Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800, Turkey. .,UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey. .,Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey. .,Department of Physics, Bilkent University, Ankara, 06800, Turkey.
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Ghobadi A, Ghobadi TGU, Karadas F, Ozbay E. Angstrom Thick ZnO Passivation Layer to Improve the Photoelectrochemical Water Splitting Performance of a TiO 2 Nanowire Photoanode: The Role of Deposition Temperature. Sci Rep 2018; 8:16322. [PMID: 30397219 PMCID: PMC6218493 DOI: 10.1038/s41598-018-34248-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 07/13/2018] [Indexed: 12/23/2022] Open
Abstract
In this paper, we demonstrate that angstrom thick single atomic layer deposited (ALD) ZnO passivation can significantly improve the photoelectrochemical (PEC) activity of hydrothermally grown TiO2 NWs. It is found that this ultrathin ZnO coating can passivate the TiO2 surface defect states without hampering the carrier's transfer dynamics. Moreover, a substantial improvement can be acquired by changing the deposition temperature of the ZnO layer (80 °C, and 250 °C) and named as 80 °C TiO2-ZnO, and 250 °C TiO2-ZnO. It was found that the deposition of this single layer in lower temperatures can lead to higher PEC activity compared to that deposited in higher ones. As a result of our PEC characterizations, it is proved that photoconversion efficiency of bare TiO2 NWs can be improved by a factor of 1.5 upon coating it with a single ZnO layer at 80 °C. Moreover, considering the fact that this layer is a passivating coating rather than a continuous layer, it also keeps the PEC stability of the design while this feature cannot be obtained in a thick shell layer case. This paper proposes a bottom up approach to control the electron transfer dynamics in a heterojunction design and it can be applied to other metal oxide combinations.
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Affiliation(s)
- Amir Ghobadi
- UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.,NANOTAM - Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.,Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800, Turkey
| | - Turkan Gamze Ulusoy Ghobadi
- UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey.,Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey.,Department of Energy Engineering, Faculty of Engineering, Ankara University, Ankara, 06830, Turkey
| | - Ferdi Karadas
- UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey. .,Department of Chemistry, Bilkent University, Ankara, 06800, Turkey.
| | - Ekmel Ozbay
- UNAM-National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey. .,NANOTAM - Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey. .,Department of Electrical and Electronics Engineering, Bilkent University, Ankara, 06800, Turkey. .,Department of Physics, Bilkent University, Ankara, 06800, Turkey.
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Large-Area, Cost-Effective, Ultra-Broadband Perfect Absorber Utilizing Manganese in Metal-Insulator-Metal Structure. Sci Rep 2018; 8:9162. [PMID: 29907773 PMCID: PMC6003956 DOI: 10.1038/s41598-018-27397-y] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 06/01/2018] [Indexed: 11/09/2022] Open
Abstract
Achieving broadband absorption has been a topic of intensive research over the last decade. However, the costly and time consuming stage of lithography has always been a barrier for the large-area and mass production of absorbers. In this work, we designed, fabricated, and characterized a lithography-free, large-area compatible, omni-directional, ultra-broadband absorber that consists of the simplest geometrical configuration for absorbers: Metal-Insulator-Metal (MIM). We introduced and utilized Manganese (Mn) for the first time as a very promising metal for broadband absorption applications. We optimized the structure step-by-step and compared Mn against the other best candidates introduced so far in broadband absorption structures and showed the better performance of Mn compared to them. It also has the advantage of being cheaper compared to metals like gold that has been utilized in many patterned broadband absorbers. We also presented the circuit model of the structure. We experimentally achieved over 94 percent average absorption in the range of 400-900 nm (visible and above) and we obtained absorption as high as 99.6 percent at the wavelength of 626.4 nm. We also experimentally demonstrated that this structure retains broadband absorption for large angles up to 70 degrees.
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Hajian H, Ghobadi A, Butun B, Ozbay E. Nearly perfect resonant absorption and coherent thermal emission by hBN-based photonic crystals. OPTICS EXPRESS 2017; 25:31970-31987. [PMID: 29245865 DOI: 10.1364/oe.25.031970] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 12/01/2017] [Indexed: 06/07/2023]
Abstract
In this paper, we numerically demonstrate mid-IR nearly perfect resonant absorption and coherent thermal emission for both polarizations and wide angular region using multilayer designs of unpatterned films of hexagonal boron nitride (hBN). In these optimized structures, the films of hBN are transferred onto a Ge spacer layer on top of a one-dimensional photonic crystal (1D PC) composed of alternating layers of KBr and Ge. According to the perfect agreements between our analytical and numerical results, we discover that the mentioned optical characteristic of the hBN-based 1D PCs is due to a strong coupling between localized photonic modes supported by the PC and the phononic modes of hBN films. These coupled modes are referred as Tamm phonons. Moreover, our findings prove that the resonant absorptions can be red- or blue-shifted by changing the thickness of hBN and the spacer layer. The obtained results in this paper are beneficial for designing coherent thermal sources, light absorbers, and sensors operating within 6.2 μm to 7.3 μm in a wide angular range and both polarizations. The planar and lithography free nature of this multilayer design is a prominent factor that makes it a large scale compatible design.
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