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Integrated electro-optic modulators in x-cut lithium niobate thin film
摘要： Integrated optics is poised to revolutionize several data communication applications. The development of high performance electro-optic modulators is essential for the technology to be viable. In this paper, single-mode electro-optic modulators in x-cut lithium niobate thin film are designed, simulated, and analyzed. The single-mode conditions of lithium niobate ridge waveguides are analyzed in detail. The design parameters of Y-branch and separation distances between electrodes and ridge waveguides are optimized. The half-wave voltage of the electro-optic modulator with device lengths of 10 mm is determined. The half-wave voltage-length product is about 2.2 V·cm, indicating the efficient electric-optical modulation. This study is helpful for understand of electro-optic modulator structures in lithium niobate thin film, as well as for the fabrication of high-performance and multifunctional electro-optic modulation devices.
关键词： Electro-optic modulator,Lithium niobate thin film,Waveguide devices,Integrated optics
更新于2025-09-23 15:21:01
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Deposition and characterization of earth abundant <scp>CuZnS</scp> ternary thin films by vacuum spray pyrolysis and fabrication of <scp>pa??</scp> CZS/ <scp>na??AZO</scp> heterojunction solar cells
摘要： We report fabrication of solar cell device <ITO/AZO/i-ZnO/CZS/Al> with Copper Zinc Sulfide (CZS) thin films as absorber layer. CZS thin films prepared using chemical spray pyrolysis technique at a pressure of 10?3 mbar at different substrate temperatures. Structural, morphological, optical, compositional and electrical properties of as prepared films are investigated. Structural analysis shows crystalline nature with mixed phase containing CuS-ZnS binary composite. Atomic Force Microscopy analysis shows the average particle size of 88 nm. Value of work function obtained from ultraviolet photoelectron spectroscopy is 4.58 eV. The band gap of the as-prepared films varies from 1.62 to 2.06 eV. Hall effect measurement proves the p-type nature for all the deposited films. Samples deposited at 350°C shows carrier concentration of 1021 cm?3 and electrical conductivity of 526 S cm?1. Solar cell device structure of <ITO/AZO/i-ZnO/CZS/Al> has been fabricated using the CZS sample deposited at 350°C. The cell parameters obtained are Voc = 0.505 V, Isc = 4.97 mA/cm2, FF = 64.28% and η = 1.6 ± 0.05%.
关键词： solar cell,heterojunction,ternary compound,thin film,absorber layer,vacuum spray pyrolysis
更新于2025-09-23 15:21:01
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Synthesis, DFT studies, fabrication, and optical characterization of the [ZnCMC] <sup>TF</sup> polymer (organic/inorganic) as an optoelectronic device
摘要： A novel carboxymethyl cellulose zinc thin film [ZnCMC]TF was fabricated using the sol–gel technique. Different characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible spectroscopy (UV-Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and the optical properties were used to study the properties of [ZnCMC]TF. The molecular structure, FTIR, and optical properties were optimized. The Raman spectrum of the [ZnCMC]TF complex shows several bands in the range of 72–556 cm?1 due to (nZn–O) stretching and (Zn–O) bending, which is an obvious distinction between the FTIR and Raman spectra of [ZnCMC]TF. The optimization was performed using density functional theory (DFT) by DMol3 and Cambridge Serial Total Energy Package (CASTEP) program. The chemical structure was confirmed by spectroscopic and structural properties for both CMC and [ZnCMC]TF; the XRD results showed the same crystal structure (Monoclinic 2). [ZnCMC]TF has a larger grain size than CMC and has a similar behavior in the optical gap energy. The optical constants increased with increasing photon energy, refractive index n, absorption index k, and optical conductivity. The SEM images provide very good evidence in favor of the reaction of zinc transition metal with CMC for the formation of the [ZnCMC]TF complex. The resulting [CMC] spherical thin film and the [ZnCMC]TF polymeric nanorods were examined by different techniques including TEM and EDX. The optical properties obtained from the simulated FTIR, XRD, and CASTEP are in good agreement with those obtained from the experimental studies on CMC and ZnCMC. Based on the optical findings, [ZnCMC]TF is a promising candidate in applications such as solar cells and optoelectronic devices.
关键词： TEM,DMol3,zinc thin film,carboxymethyl cellulose,UV-Vis,DFT,optoelectronic devices,XRD,EDX,CASTEP,sol–gel technique,SEM,FTIR,optical properties,Raman spectroscopy
更新于2025-09-23 15:21:01
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Si-doping effect on solution-processed In-O thin-film transistors
摘要： In this work, silicon-doped indium oxide thin-film transistors (TFTs) have been fabricated for the first time by a solution processing method. By varying the Si concentration in the In2O3-SiO2 binary oxide structure up to 15 at.%, the thicknesses, densities, and crystallinity of the resulting In-Si-O (ISO) thin films were investigated by X-ray reflectivity (XRR) and X-ray diffraction techniques, while the produced TFTs were characterized by a conventional three-probe method. The results of XRR analysis revealed that the increase in the content of Si dopant increased the thickness of the produced film and reduced its density, and that all the Si-doped ISO thin films contained only a single amorphous phase even after annealing at temperatures as high as 800 °C. The manufactured ISO TFTs exhibited a reduction in the absolute value of threshold voltage VT close to 0 V and low current in the off-state, as compared to those of the non-doped indium oxide films, due to the reduced number of oxygen defects, which was consistent with the behavior of ISO TFTs fabricated by a sputtering method. The ISO TFT with a Si content of 3 at.% annealed at 400 °C demonstrated the smallest subthreshold swing of 0.5 V/dec, VT of ?5 V, mobility of 0.21 cm2/Vs, and on/off current ratio of about 2×107.
关键词： silicon-doped indium oxide,solution processing,amorphous oxide semiconductor,thin-film transistor,spin coating
更新于2025-09-23 15:21:01
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Improved Photoelectric Properties of ZnO<sub>1-x</sub>/Graphene Heterostructures
摘要： In this work, the photoelectric properties of ZnO1-x/graphene heterostructures were investigated. Such ZnO1-x/graphene heterostructures were constructed from non-stoichiometric zinc oxide (ZnO1-x) film and graphene by first depositing ZnO1-x layer through radio frequency magnetron sputtering onto silicon wafers with SiO2 layer and then transferring graphene via a wet method. It was revealed that such heterostructures could have improved photoelectric properties. Compared with ZnO1-x films, the absorbance of the ZnO1-x/graphene heterostructures in visible and near-infrared region was enhanced; and due to the high conductivity of graphene, the photocurrent was significantly enhanced both in dark and under irradiation of a 700 nm light. By calculating the absolute current gain, it was revealed that the fabricated ZnO1-x/graphene heterostructures would have a higher current gain. Thus, such ZnO1-x/graphene heterostructures would be promisingly applied in visible light to near-infrared detection devices.
关键词： Thin film,Zinc oxide,Photoelectric properties,Device,Graphene
更新于2025-09-23 15:21:01
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Influence of Reactive Ion Etching on THz Transmission and Reflection Properties of NiCr Film Deposited on a Dielectric Substrate
摘要： Enhanced terahertz (THz) absorption of NiCr film deposited on a dielectric substrate has been proven by applying a reactive ion etching (RIE) treatment to the dielectric film. Nano-scale nickel-chromium (NiCr) thin films are deposited on RIE treated silicon dioxide (SiO2) dielectric substrates to study the transmission and reflection characteristics. Experimental results suggest that both transmission and reflection of NiCr film are weakened by the RIE treatment. The most significant decrease of transmission is observed in (1 ~ 4) THz while that of reflection occurs in (1.7 ~ 2.5) THz band. The decrease of both transmission and reflection is more significant for NiCr film with higher thickness. The RIE treatment, which induces a roughened surface of SiO2 substrate and increases the effective surface area of NiCr film, enhances the absorption and weakens the transmission and reflection of THz radiation.
关键词： NiCr thin film,transmission,RIE,THz,reflection,absorption
更新于2025-09-23 15:21:01
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Dielectric relaxation and resistive switching of Bi0.96Sr0.04Fe0.98Co0.02O3/CoFe2O4 thin films with different thicknesses of the Bi0.96Sr0.04Fe0.98Co0.02O3 layer
摘要： Bi0.96Sr0.04Fe0.98Co0.02O3/CoFe2O4(BSFCO/CFO) bilayered thin films with different thicknesses of the BSFCO layer are synthesized on FTO/glass substrates by chemical solution deposition method (CSD). The influence of BSFCO thickness on the microstructure, dielectric relaxation, ferroelectric properties and resistive switching (RS) of the thin films are researched. Strain exists in the prepared thin films and gives rise to structural distortion, which has an effect on charged defects and ferroelectric polarization. Dielectric relaxation that is closely related to the interfacial polarization at the BSFCO/CFO interface is observed, and the dielectric loss peaks along with decreasing intensity shift to high frequency with decreasing strain. The Maxwell-Wagner two-layer model is adopted to investigate the mechanism of dielectric relaxation, and the relaxation time τ is calculated and it shown to be directly proportional to the strain. It is found that the dielectric properties, including low dielectric loss, can be improved by controlling the BSFCO layer thickness. The ferroelectric properties improve with the decreasing strain, the 12-BSFCO/CFO thin film possesses a large Pr~102.9 μC/cm2 at 660 kV/cm. The observed resistive switching (RS) behavior is attributed to the interfacial conduction mechanism, it is found that strain-dependent the ferroelectric polarization switching modulates the width of depletion layer and the height of potential barrier at the interface, resulting in the different resistance states.
关键词： dielectric relaxation,bilayered thin film,BiFeO3,resistive switching,strain
更新于2025-09-23 15:21:01
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Development of an ultra thin beam profiler for charged particle beams
摘要： Beam profiling during patient treatment in protontherapy requires ultra-thin monitors to preserve the high beam quality. For detectors upstream in the line, a material budget as low as ～ 15 μm water-equivalent is needed. In addition, the current trend of dose escalation to treat highly resistant tumors implies challenging requirements on monitor radiation hardness and dynamic range. We propose a new type of beam profiler, PEPITES, using secondary electron emission (SEE) and built with thin-film techniques. The beam is profiled by crossing a pattern or a series of patterns which emit the SEE signal and can be made ultra-thin as SEE originates from the few nanometers next to the surface. The patterns are deposited on membranes, which, in contrast with common systems like ionization chambers, are free from mechanical constraints and can then afford higher absorbed doses and be as thin as achievable. A simple demonstrator prototype has been built and successfully operated with a proton beam at the ARRONAX cyclotron at St Herblain in a wide range of currents (100 fA to 10 nA) and several energies (30 - 68 MeV). Beam profiling results from these tests are presented, and our plans for the next prototypes are mentioned.
关键词： Protontherapy,Thin film,Beam profiler
更新于2025-09-23 15:21:01
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Intrinsic Sub-Nanocrystalline Silicon Thin Films: Active Layer for Solar Cells
摘要： The study presents the typical aspects of silicon thin films in terms of growth under variation of applied power using Radio frequency Plasma Enhanced Chemical Vapor Deposition technique (RF-PECVD). The corresponding material found to maintain the typical properties of amorphous nature without compensating the structural modification in terms of crystallinity and has been defined as a material having the “sub-nanocrystalline phase”. Characterizations like, UV-Visible spectroscopy, Photoluminescence and Temperature dependent conductivity was used to effectively map the structural details along with electrical and optical properties. The optical bandgap of the films found to be vary from 1.77 eV to 1.99 eV with typical photoresponse variations in the range 103 to 101. At 30 W applied power, the transition regime observed with the formation of sub-nanocrystallites. The analysis of such phase reveals the superior optoelectronic properties. This article suggests the suitability of sub-nanocrystalline silicon thin films to replace hydrogenated amorphous silicon in various applications.
关键词： Nc-Si:H/μc-Si:H,Thin film,PECVD,Sub-nanocrystalline phase,Conductivity
更新于2025-09-23 15:19:57
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Inorganic and Pb-Free CsBi <sub/>3</sub> I <sub/>10</sub> Thin Film for Photovoltaic Applications
摘要： Computational, thin-film deposition and characterization approaches have been used to investigate the all inorganic lead-free CsBi3I10 as a candidate thin-film photovoltaic absorber. In this paper, CsBi3I10 was firstly predicted with a layer crystal structure of stable hexagonal phase like Cs3Bi2I9 and then prepared by one-step coating also showing the high purity hexagonal phase and crystallinity, very consistent with the theoretical calculation. After solvent annealing, a high absorption coefficient of approximately 105 cm?1 in visible light and a suitable optical bandgap of 1.78 eV were obtained for CsBi3I10 thin film. The solar cell based on CsBi3I10 perovskite thin film exhibited high power conversion efficiency of 1.05%, good reproducibility, hysteresis-freeness, and long-term stability. These results indicate that the performance of all-inorganic Pb-free perovskite solar cells can be further improved.
关键词： thin-film photovoltaic absorber,perovskite solar cells,CsBi3I10,solvent annealing,lead-free
更新于2025-09-23 15:19:57