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Preparation and characterization of lead zirconate titanate thin films grown by RF magnetron sputtering for pyroelectric infrared detector arrays
摘要： One of the challenges in fabricating pyroelectric infrared (PIR) detector arrays using microelectromechanical system (MEMS) technique lies in finding an optimal growth method of sensing thin films. In this study, lead zirconate titanate (PbZr0.3Ti0.7O3, PZT) thin films were successfully prepared on Pt/TiO2/Si3N4/SiO2/Si substrates by RF magnetron sputtering. The structure, morphology and electrical properties of the films annealed at different temperatures were investigated. PZT thin films deposited at a working pressure of 3.0 Pa with an Ar/O2 gas flow ratio of 80/20 and annealed at 700 °C exhibited smooth surface and excellent dielectric, ferroelectric and pyroelectric properties. The dielectric constant and the loss tangent of the films are 500 and 0.018 at 1 kHz, respectively. The remnant polarization (Pr) and the coercive field (Ec) of the films are 33 μC cm?2 and 42 kV cm?1, respectively. The pyroelectric coefficient of the films is 0.033 μC cm?2 K?1. The value of the figure of merit of detectivity (FD) of PZT thin films reaches up to 1.29 × 10?5 Pa?1/2, which indicates that the films have met the requirements for sensitive layers utilized in pyroelectric infrared detector arrays.
关键词： RF magnetron sputtering,Pyroelectric infrared detector arrays,PZT thin films
更新于2025-09-23 15:21:01
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Ternary Hierarchical Cu <sub/>7</sub> S <sub/>4</sub> /TiO <sub/>2</sub> /CoCr-LDH Heterostructured Nanorod Arrays with Multiphase Reaction Interfaces for More Efficient Photoelectrochemical Water Splitting
摘要： Fabricating hierarchical and highly matched heterostructure with large surface areas and multiple interfaces is an effective approach to enhancing the photoelectrochemical performance. Here, well-aligned hierarchical Cu7S4/TiO2/CoCr-layered double hydroxide (LDH) nanorod arrays are reported, aiming at accelerating charge separation and transfer kinetics. The modifications of Cu7S4 and CoCr-LDH based on TiO2 have endowed the photoanode a surprising enhancement in both ultraviolet light absorption and charge separation efficiency due to highly matched band alignment. The formation of heterojunction is an effective strategy to prevent photocorrosion of Cu7S4 by attaching protective layers on Cu7S4. Moreover, other than the hierarchical morphology with enlarged active surface areas would provide sufficient active sites for the water oxidation processes and pore channels for the gas escaping, owing to the special band alignment of three components, multiple reaction interfaces are produced and involved in the water splitting process, since the photoinduced holes for water oxidation are simultaneously distributed in CoCr-LDH and Cu7S4. As expected, this synergistic effect in this ternary Cu7S4/TiO2/CoCr-LDH heterogeneous photoanode gives rise to a largely enhanced photoconversion efficiency (0.58% at 0.6 V) and photocurrent density (2.04 mA cm?2 at 1.23 V).
关键词： 3D hierarchical nanorod arrays,Cu7S4/TiO2/CoCr-LDH,ternary heterostructure,highly matched band alignment,photoelectrochemical water splitting
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Space PV Concentrators for Outer Planet and Near-Sun Missions, Using Ultra-Light Fresnel Lenses Made with Vanishing Tools
摘要： The Kilpisj?rvi Atmospheric Imaging Receiver Array (KAIRA) is a dual array of omnidirectional VHF radio antennas located near Kilpisj?rvi, Finland. It is operated by the Sodankyl? Geophysical Observatory. It makes extensive use of the proven LOFAR antenna and digital signal-processing hardware, and can act as a stand-alone passive receiver, as a receiver for the European Incoherent Scatter (EISCAT) very high frequency (VHF) incoherent scatter radar in Troms?, or for use in conjunction with other Fenno-Scandinavian VHF experiments. In addition to being a powerful observing instrument in its own right, KAIRA will act as a pathfinder for technologies to be used in the planned EISCAT_3-D phased-array incoherent scatter radar system and participate in very long baseline interferometry experiments. This paper gives an overview of KAIRA, its principal hardware and software components, and its main science objectives. We demonstrate the applicability of the radio astronomy technology to our geoscience application. Furthermore, we present a selection of results from the commissioning phase of this new radio observatory.
关键词： receiving antennas,radio astronomy,radar antennas,Antenna arrays,phased arrays
更新于2025-09-23 15:19:57
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In Situ Raman Investigation of TiO2 Nanotube Array-Based Ultraviolet Photodetectors: Effects of Nanotube Length
摘要： TiO2 nanotube arrays (TNAs) with tube lengths of 4, 6, and 7 μm were prepared via two-step anodization. Thereafter, ultraviolet (UV) photodetectors (PDs) with Au/TiO2/Au structures were prepared using these TNAs with different tube lengths. The effects of TNA length and device area on the performance of the device were investigated using in situ Raman spectroscopy. The maximum laser/dark current ratio was achieved by using a TNA with a size of 1 × 1 cm2 and a length of 7 μm, under a 532 nm laser. In addition, when the device was irradiated with a higher energy laser (325 nm), the UV Raman spectrum was found to be more sensitive than the visible Raman spectrum. At 325 nm, the laser/dark current ratio was nearly 24 times higher than that under a 532 nm laser. Six phonon modes of anatase TNAs were observed, at 144, 199, 395, 514, and 635 cm?1, which were assigned to the Eg(1), Eg(2), B1g(1), A1g/B1g(2), and Eg(3) modes, respectively. The strong low-frequency band at 144 cm?1 was caused by the O-Ti-O bending vibration and is a characteristic band of anatase. The results show that the performance of TNA-based PDs is length-dependent. Surface-enhanced Raman scattering signals of 4-mercaptobenzoic acid (4-MBA) molecules were also observed on the TNA surface. This result indicates that the length-dependent performance may be derived from an increase in the specific surface area of the TNA. In addition, the strong absorption of UV light by the TNAs caused a blueshift of the Eg(1) mode.
关键词： UV photodetector,Surface-enhanced Raman scattering,TiO2 nanotube arrays,SERS,Raman spectroscopy
更新于2025-09-23 15:19:57
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Controllable Growth of Higha??Quality Inorganic Perovskite Microplate Arrays for Functional Optoelectronics
摘要： Inorganic perovskite single crystals have emerged as promising vapor-phase processable structures for optoelectronic devices. However, because of material lattice mismatch and uncontrolled nucleation, vapor-phase methods have been restricted to random distribution of single crystals that are difficult to perform for integrated device arrays. Herein, an effective strategy to control the vapor-phase growth of high-quality cesium lead bromide perovskite (CsPbBr3) microplate arrays with uniform morphology as well as controlled location and size is reported. By introducing perovskite seeds on substrates, intractable lattice mismatches and random nucleation barriers are surpassed, and the epitaxial growth of perovskite crystals is accurately controlled. It is further demonstrated that CsPbBr3 microplate arrays can be monolithically integrated on substrates for the fabrication of high-performance lasers and photodetectors. This strategy provides a facile approach to fabricate high-quality CsPbBr3 microplates with controllable size and location, which offers new opportunities for the scalable production of integrated optoelectronic devices.
关键词： perovskites,microdevice arrays,vapor patterning,single crystals
更新于2025-09-23 15:19:57
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Ultrathin InP annular nanohole arrays for efficient light absorption solar cells
摘要： This Letter proposes ultrathin InP films consisting of annular nanohole arrays (ANAs) for highly efficient solar cells. By tailoring the inner and outer radii of ANAs properly and combining antireflection coating (ZnO) and back-reflector (Ag), the photocurrent generated in the InP based dielectric-semiconductor-metal (DSM) configuration can be increased dramatically by 124.6% with respect to the planar solar cell of equal geometric thickness (100 nm). The fact that the DSM-ANA structure is able to harvest broadband and wide-angle incident light can be attributed to the excitation of leaky waveguide modes, Bloch modes, and surface plasmon polariton modes. This work provides a promising and feasible way to design and fabricate efficient ultrathin InP photovoltaic and other optoelectronic devices.
关键词： light absorption,ultrathin InP films,dielectric-semiconductor-metal configuration,annular nanohole arrays,surface plasmon polariton modes,solar cells
更新于2025-09-23 15:19:57
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Chiral effects in low-cost plasmonic arrays of elliptic nanoholes
摘要： In this work we present an approach to induce chiral effects in well-known plasmonic nanohole arrays with triangular unit cell. Arrays with circular nanoholes in metals can exhibit interesting light-matter interaction mechanisms such as surface plasmon polaritons and extraordinary optical transmission. Moving from circular to elliptical shape and tilting the ellipse away from the lattice symmetry lines, a symmetry breaking induces a different absorption of the circularly polarized light of opposite handedness, i.e. circular dichroism. We numerically investigate circular dichroism at normal incidence in elliptic nanoholes in Au in the spectral range 400–1000 nm. We focus on its dependence on the elliptic nanohole tilt, and further proceed with the ellipse radii optimization. The optimized circular dichroism reaches 84%, and we report on the near field absorption distribution at the wavelengths of this maximum value.
关键词： Nanohole arrays,Enantiomers,Plasmonics,Chirality
更新于2025-09-23 15:19:57
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Self-Organized Nanorod Arrays for Large-Area Surface Enhanced Infrared Absorption
摘要： Highly sensitive Surface Enhanced Infrared Absorption (SEIRA) spectroscopy capabilities are demonstrated by exploiting large-area templates (cm2) based on self-organized (SO) nanorod antennas. We engineered highly dense arrays of gold nanorod antennas featuring polarization-sensitive localized plasmon resonances, tunable over a broadband near- and mid-infrared (IR) spectrum, in overlap with the so called ‘functional group’ window. We demonstrate polarization-sensitive SEIRA activity, homogenous over macroscopic areas and stable in time, by exploiting prototype self-assembled monolayers of IR-active octadecanthiol (ODT) molecules. The strong coupling between the plasmonic excitation and the molecular stretching modes give rise to characteristic Fano resonances in SEIRA. The SO engineering of the active hot-spots in the arrays allows to achieve signal amplitude improved up to the 5.7 %. This figure is competitive to the response of lithographic nanoantennas and is stable when the optical excitation spot varies from the micro- to the macroscale, thus enabling highly sensitive SEIRA spectroscopy on cost-effective nanosensor devices.
关键词： IR spectroscopy,large area nanosensors,Surface Enhanced Infra-Red Absorption (SEIRA),self-organized arrays,Fano resonances,Plasmonic nanoantennas
更新于2025-09-23 15:19:57
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Impact of metal crystallinity-related morphologies on the sensing performance of plasmonic nanohole arrays
摘要： Plasmonic nanohole arrays for biosensing applications have attracted tremendous attention because of their flexibility in optical signature design, high multiplexing capabilities, simple optical alignment setup, and high sensitivity. The quality of the metal film, including metal crystallinity and surface roughness, plays an important role in determining the sensing performance because the interaction between free electrons in the metal and incident light is strongly influenced by the metal surface morphology. We systematically investigated the influence of metal crystallinity-related morphologies on the sensing performance of plasmonic nanohole arrays after different metal deposition processes. We utilised several non-destructive nanoscale surface characterisation techniques to perform a quantitative and comparative analysis of the Au quality of the fabricated sensor. We found empirically how the surface roughness and grain sizes influence the permittivity of the Au film and thus the sensitivity of the fabricated sensor. Finally we confirmed that the deposition conditions that provide both low surface roughness and large metal grain sizes improve the sensitivity of the plasmonic sensor.
关键词： sensitivity,Plasmonic nanohole arrays,biosensing,metal crystallinity,surface roughness
更新于2025-09-23 15:19:57
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Enhanced current density of anatase TiO2 nanowire arrays by interface connection modulation in flexible quantum dot sensitized solar cells
摘要： The stability and photovoltaic conversion efficiency are very important issues for the industry application of flexible solar cells, which have been seriously limited by the interface connection of basic photo-electrodes in solar cells. Here, one-dimensional TiO2 nanowire arrays films were employed as photo-electrodes of flexible solar cells, which have modulated interface connection of the photo-electrodes by introducing small size of nanoparticles and heating pressure process. The charge generation and separation properties of photo-electrodes have been influenced, which may be attributed by the changes on band energy of small size of nanoparticles in photo-electrodes. With the improvement on the interface connection in the photo-electrodes, the charge transfer property has been effectively improved, which have exhibited a higher current density value of the solar cells, achieving photovoltaic conversion efficiency enhancement from 2.55% to 3.90%. Moreover, there have no obvious changes on the photovoltaic conversion efficiency of these flexible QDSSCs solar cells under the curling condition.
关键词： Anatase TiO2 nanowire arrays,Flexible quantum dot sensitized solar cell,Interface connection,Photovoltaic performance enhancement,Small size of nanoparticles,Heating pressure
更新于2025-09-23 15:19:57