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12 pages, 1873 KiB

Open AccessEditor’s ChoiceArticle

High-Entropy Perovskite Thin Film in the Gd-Nd-Sm-La-Y-Co System: Deposition, Structure and Optoelectronic Properties

by Pawel A. Krawczyk, Wojciech Salamon, Mateusz Marzec, Michał Szuwarzyński, Jakub Pawlak, Jarosław Kanak, Małgorzata Dziubaniuk, Władyslaw W. Kubiak and Antoni Żywczak

Materials 2023, 16(12), 4210; https://doi.org/10.3390/ma16124210 - 6 Jun 2023

Cited by 6 | Viewed by 6222

Abstract

Multicomponent equimolar perovskite oxides (ME-POs) have recently emerged as a highly promising class of materials with unique synergistic effects, making them well-suited for applications in such areas as photovoltaics and micro- and nanoelectronics. High-entropy perovskite oxide thin film in the (Gd_0.2Nd_0.2La_0.2Sm_0.2Y_0.2)CoO₃ (RECO, where RE = Gd_0.2Nd_0.2La_0.2Sm_0.2Y_0.2, C = Co, and O = O₃) system was synthesized via pulsed laser deposition. The crystalline growth in an amorphous fused quartz substrate and single-phase composition of the synthesized film was confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Surface conductivity and activation energy were determined using a novel technique implementing atomic force microscopy (AFM) in combination with current mapping. The optoelectronic properties of the deposited RECO thin film were characterized using UV/VIS spectroscopy. The energy gap and nature of optical transitions were calculated using the Inverse Logarithmic Derivative (ILD) and four-point resistance method, suggesting direct allowed transitions with altered dispersions. The narrow energy gap of RECO, along with its relatively high absorption properties in the visible spectrum, positions it as a promising candidate for further exploration in the domains of low-energy infrared optics and electrocatalysis. Full article

(This article belongs to the Special Issue Advanced Energy Materials for Solar Cells, Photocatalysis, and Optoelectronic Devices)

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13 pages, 19824 KiB

Open AccessArticle

THz MEMS Switch Design

by Yukang Feng, Han-yu Tsao and N. Scott Barker

Micromachines 2022, 13(5), 745; https://doi.org/10.3390/mi13050745 - 8 May 2022

Cited by 10 | Viewed by 3286

Abstract

In this work, an mm-wave/THz MEMS switch design process is presented. The challenges and solutions associated with the switch electrical design, modeling, fabrication, and test are explored and discussed. To investigate the feasibility of this design process, the switches are designed on both silicon and fused quartz substrate and then tested in the 140–750 GHz frequency range. The measurement fits design expectations and simulation well. At 750 GHz the measurement results from switches on both substrates have an ON state insertion loss of less than 3 dB and an OFF state isolation larger than 12 dB. Full article

(This article belongs to the Special Issue Broadband Terahertz Devices and Communication Technologies)

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18 pages, 4971 KiB

Open AccessArticle

Experimental Measurement of Sharp THz Absorption Signatures from Nucleic Acid Solutions in Nanofluidic Channels

by Elliott R. Brown and Edgar A. Mendoza

Appl. Sci. 2021, 11(24), 11827; https://doi.org/10.3390/app112411827 - 13 Dec 2021

Cited by 1 | Viewed by 2291

Abstract

We report on the room-temperature experimental measurement of THz absorption signatures in aqueous, double-stranded nucleic acid solutions confined to the submicron silica channels on fused quartz substrates using THz frequency-domain (photomixing) spectroscopy. Three sharp (i.e., strong and narrow) signatures, ~10–20 GHz FWHM, are observed in the shortest base pair sample—small interfering, double-stranded (ds) RNA—in the range of 800 GHz to 1.1 THz. Three similar signatures are also observed in a 50-bp dsDNA ladder sample. For a 1-kbp dsDNA ladder sample, the three are still evident, but are broadened and weakened. For a 48.5-kbp sample (λ-DNA), no prominent signatures are observed, but rather a quasi-sinusoidal transmittance spectrum consistent with a substrate etalon effect. The division between sharp signatures and no signatures is consistent with the molecular length being shorter or longer than the persistence length. Full article

(This article belongs to the Special Issue Terahertz Sensing)

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18 pages, 4892 KiB

Open AccessArticle

Temperature Dependence of Normalized Sensitivity of Love Wave Sensor of Unidirectional Carbon Fiber Epoxy Composite on Mn-Doped 0.24PIN-0.46PMN-0.30PT Single Crystal Substrate

by Naixing Huang, Enwei Sun, Rui Zhang, Bin Yang, Jian Liu, Tianquan Lü, Lianfu Han and Wenwu Cao

Appl. Sci. 2020, 10(23), 8442; https://doi.org/10.3390/app10238442 - 26 Nov 2020

Cited by 3 | Viewed by 1703

Abstract

Love wave sensors have attracted significant interest due to their high sensitivity and low attenuation. Love mode acoustic dispersion relation, highest normalized mass sensitivity, optimum normalized waveguide layer thickness, and temperature coefficients of frequency (TCF) were theoretically studied for the carbon fiber epoxy composites (CFEC)/Mn:0.24PIN-0.46PMN-0.30PT structure sensor. The highest normalized mass sensitivity exhibits a decreasing trend as the temperature increases from 25 °C to 55 °C. TCF can be improved by increasing the normalized layer thickness (h/λ); however, the temperature dependence of normalized mass sensitivity decreases. For the carbon fibers (CFs) in the CFEC waveguide along the propagation direction of Love wave, the device has a relatively small TCF of −10.92 ppm/°C at h/λ = 0.4001, where the normalized mass sensitivity is approximately 1.5 times that of a typical fused quartz/ST-quartz configuration device. The theoretical results imply that good temperature stability and high measurement precision were obtained from the device in the system CFEC/Mn:0.24PIN-0.46PMN-0.30PT with the CFs in the CFEC along the propagation direction of Love wave (x-axis). The ideal waveguide material requires a small elastic constant

c_{44}

; however, the ideal piezoelectric substrate requires large elastic constants

c_{44}^{E}

and

c_{66}^{E}

. Full article

(This article belongs to the Section Acoustics and Vibrations)

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10 pages, 4308 KiB

Open AccessArticle

Microchannel Fabrication in Fused Quartz by Backside Laser-Induced Plasma Ablation Using 248 nm KrF Excimer Laser

by Yu Zhao, Qian Li, Zhengfei Wang, Ziruo Dai and Tao Chen

Appl. Sci. 2019, 9(24), 5320; https://doi.org/10.3390/app9245320 - 6 Dec 2019

Cited by 10 | Viewed by 3930

Abstract

Laser-induced plasma ablation (LIPA) using a 248 nm KrF excimer laser was investigated for microchannel fabrication. Examination of the morphology in relation to ablation performance was emphasized, and a synthetic LIPA mechanism model was proposed based on the results. Backside LIPA with a metal target on the bottom can be attributed to a combination of two phenomena: laser-induced plasma vaporization thermal ablation from the metal target below and enhanced laser–glass direct interaction from the plasma residuum. The laser absorption enhancement of quartz substrate resulting from the metal residuum was validated clearly using absorption spectrum measurements. The influence of laser parameters on the etching quality during LIPA was also analyzed for processing optimization. Finally, fused quartz glass microchannels of outstanding surface quality and dimension uniformity were implemented. The channel depth was 28 μm, and the bottom surface roughness was better than several hundred nanometers. Full article

(This article belongs to the Section Applied Physics General)

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14 pages, 287 KiB

Open AccessArticle

Optical and Nonlinear Optical Response of Light Sensor Thin Films

by H. Liu, A. J. Rua, O. Vasquez, V. S. Vikhnin, L. F.E. Fernandez, F. Fonseca, O. Resto and S. Z. Weisz

Sensors 2005, 5(4), 185-198; https://doi.org/10.3390/s5040185 - 27 Apr 2005

Cited by 18 | Viewed by 11148

Abstract

For potential ultrafast optical sensor application, both VO₂ thin films andnanocomposite crystal-Si enriched SiO₂ thin films grown on fused quartz substrates weresuccessfully prepared using pulsed laser deposition (PLD) and RF co-sputteringtechniques. In photoluminescence (PL) measurement c-Si/SiO₂ film containsnanoparticles of crystal Si exhibits strong red emission with the band maximum rangingfrom 580 to 750 nm. With ultrashort pulsed laser excitation all films show extremelyintense and ultrafast nonlinear optical (NLO) response. The recorded holography fromall these thin films in a degenerate-four-wave-mixing configuration shows extremelylarge third-order response. For VO₂ thin films, an optically induced semiconductor-tometalphase transition (PT) immediately occurred upon laser excitation. it accompanied.It turns out that the fast excited state dynamics was responsible to the induced PT. For c-Si/SiO₂ film, its NLO response comes from the contribution of charge carriers created bylaser excitation in conduction band of the c-Si nanoparticles. It was verified byintroducing Eu³⁺ which is often used as a probe sensing the environment variations. Itturns out that the entire excited state dynamical process associated with the creation,movement and trapping of the charge carriers has a characteristic 500 ps duration. Full article

(This article belongs to the Special Issue Papers presented at I3S2004, Nanjing)

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