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Atomic layer deposition of zirconium oxide thin film on an optical fiber for cladding light strippers
摘要： Cladding light strippers are essential components in high-power fiber lasers used for removal of unwanted cladding light that can distort the beam quality or even damage the whole fiber laser system. In this study, an Atomic Layer Deposition system was used for the first time to prepare the cladding light stripper devices using a 40 nm thick zirconia layer grown on optical fiber. The thickness of the zirconia coating was confirmed using the Scanning Electron Microscopy (SEM) and the Ellipsometry techniques. The elemental analysis was also performed using the wavelength dispersive X-ray spectroscopy technique. The Raman spectroscopy and XRD data confirm the structure of the atomic layer deposition-grown zirconia thin films to be predominantly amorphous. The cladding light stripper devices formed using the zirconia thin films with the lengths of 8.5 and 15.5 cm were able to strip approximately 30% (~1.5 dB) and 40% (~2.3 dB) of the unwanted cladding light.
关键词： zirconium oxide,atomic layer deposition,cladding light stripper,thin film,Fiber laser
更新于2025-09-23 15:19:57
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Hybrid chemical bath deposition-CdS/sputter-Zn(O,S) alternative buffer for Cu <sub/>2</sub> ZnSn(S,Se) <sub/>4</sub> based solar cells
摘要： To replace the conventionally used CdS buffers in Cu2ZnSn(S,Se)4 (CZTSSe) based thin-film solar cells, sputtered Zn(O,S) buffer layers have been investigated. Zn(O,S) layers with three different [O]/([O] + [S]) ratios (0.4, 0.7, and 0.8)—and a combination of Zn(O,S) and CdS (“hybrid buffer layer”) were studied. In comparison to the CdS reference, the external quantum efficiency (EQE) of the Zn(O,S)-buffered devices increases in the short- and long-wavelength regions of the spectrum. However, the average EQE ranges below that of the CdS reference, and the devices show a low open-circuit voltage (VOC). By adding a very thin CdS layer (5 nm) between the absorber and the Zn(O,S) buffer, the VOC loss is completely avoided. Using thicker intermediate CdS layers result in a further device improvement, with VOC values above those of the CdS reference. X-ray photoelectron spectroscopy (XPS) measurements suggest that the thin CdS layer prevents damage to the absorber surface during the sputter deposition of the Zn(O,S) buffer. With the hybrid buffer configuration, a record VOC deficit, i.e., a minimum difference between bandgap energy Eg (divided by the elementary charge q) and VOC (Eg/q – VOC) of 519 mV could be obtained, i.e., the lowest value reported for kesterite solar cells to date. Thus, the hybrid buffer configuration is a promising approach to overcome one of the main bottlenecks of kesterite-based solar cells, while simultaneously also reducing the amount of cadmium needed in the device.
关键词： VOC deficit,Cu2ZnSn(S,Se)4,CdS,hybrid buffer layer,open-circuit voltage,X-ray photoelectron spectroscopy,thin-film solar cells,Zn(O,S) buffer layers,external quantum efficiency
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - Atlanta, GA, USA (2019.7.7-2019.7.12)] 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - A Unit-Cell Discontinuous Galerkin Scheme for Analyzing Plasmonic Photomixers
摘要： Disordered ionic-bonded transition metal oxide thin-film transistors (TFTs) show promise for a variety of dc and RF switching applications, especially those that can leverage their low-temperature, substrate-agnostic process integration potential. In this paper, enhancement-mode zinc-oxide TFTs were fabricated and their switching performance evaluated. These TFTs exhibit the drain-current density of 0.6 A/mm and minimal frequency dispersion, as evidenced by dynamic current–voltage tests. A high-frequency power switch figure of merit RON QG of 359 mΩ · nC was experimentally determined for 0.75-μm long-channel devices, and through scaling 45.9 mΩ · nC is achievable for 11 V-rated devices (where RON is ON-state drain–source resistance, and QG is gate charge). An RF switch cutoff frequency fc of 25 GHz was measured for the same 0.75-μm TFT, whereas fc exceeding 500 GHz and power handling in the tens of watts are projected with optimization.
关键词： zinc oxide,dc switch,Cutoff frequency,pulse measurements,gate charge,monolithic ICs,RF switch,ionic semiconductors,thin-film transistors (TFTs)
更新于2025-09-23 15:19:57
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Narrow bandgap difluorobenzochalcogenadiazole-based polymers for high-performance organic thin-film transistors and polymer solar cells
摘要： A bithiophene donor unit, 3-alkoxy-3’-alkyl-bithiophene (TRTOR), was copolymerized with difluorobenzochalcogenadiazole (ffBZ) containing different heteroatoms on their diazole structure to afford a series of PffBZ copolymers (where Z = X, T, Se) with narrow optical bandgaps in the range of 1.34-1.47 eV. The effects of ffBZ heteroatoms (O, S, and Se) on the optical properties, electrochemical characteristics and film morphologies of polymers as well as device performance were fully investigated. The results revealed that the highest occupied molecular orbitals (HOMOs) of polymers are gradually elevated accompanied by increased material solubility in common organic solvents as the size of heteroatoms increases. The PffBZ copolymers exhibit substantial hole mobility of 0.08-1.6 cm2 V-1 s-1 in organic thin-film transistors (OTFTs). The PffBX, PffBT, and PffBSe-based polymers exhibit maximum power conversion efficiencies (PCEs) of 5.47%, 10.12%, and 3.65%, respectively in polymer solar cells (PSCs). For PffBZ copolymers, the alkyl chain exerts a great influence on the morphology of the polymer:PC71BM blend films and hence affect PCEs in PSCs. It was found that the performing of polymers branching on the 2nd position for alkyl chain and the 3rd position for alkoxy chain were the best among PffBT and PffBSe-based polymers, and it is different from the tetrathiophene-based benchmark polymer branching on the 2nd position of the alkyl chain. X-ray diffraction revealed that all PffBZ-based polymers has obvious a face-on dominated orientation, and that chalcogen atom and branched position on alkoxy chain have a great influence on the morphologies of neat and blend films. The above results indicated that the branching positions and chalcogen atoms should be carefully optimized to maximize performance.
关键词： polymer solar cells,high-performance,difluorobenzochalcogenadiazole,organic thin-film transistors,narrow bandgap
更新于2025-09-23 15:19:57
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Thin-film flip-chip UVB LEDs realized by electrochemical etching
摘要： We demonstrate a thin-?lm ?ip-chip (TFFC) light-emitting diode (LED) emitting in the ultraviolet B (UVB) at 311 nm, where substrate removal has been achieved by electrochemical etching of a sacri?cial Al0:37Ga0:63N layer. The electroluminescence spectrum of the TFFC LED corresponds well to the as-grown LED structure, showing no sign of degradation of structural and optical properties by electrochemical etching. This is achieved by a proper epitaxial design of the sacri?cial layer and the etch stop layers in relation to the LED structure and the electrochemical etch conditions. Enabling a TFFC UV LED is an important step toward improving the light extraction ef?ciency that limits the power conversion ef?ciency in AlGaN-based LEDs.
关键词： Thin-film flip-chip,AlGaN,light extraction efficiency,UVB LEDs,electrochemical etching
更新于2025-09-23 15:19:57
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Investigation of physical properties of F-and-Ga co-doped ZnO thin films grown by RF magnetron sputtering for perovskite solar cells applications
摘要： F-and-Ga co-doped ZnO films were sputter-deposited on glass substrates by RF magnetron sputtering method. The fabricated films were characterized by different techniques. It was found that all the films were poly-crystalline with a hexagonal wurtzite structure with a c-axis preferred orientation of growth. The effect of the substrate temperature on the surface morphology, electrical and optical properties of the films was also investigated. The optimal growth temperature was found to be 440 oC which led to the optimal film with the resistivity of 6.81 × 10?4 Ωcm, carrier concentration of 2.61 × 1020 cm?3, mobility of 35.1 cm2/V, over-90% transmittance in the region of 400–1200 nm and a wide optical bandgap of 3.49 eV. This optimal film was employed in as the front contact in perovskite solar cells and resulted in a high power-conversion efficiency of 15.32%. This indicates that such a film can be promisingly useful for high-performance thin-film solar cells.
关键词： High mobility,Thin-film solar cells,F-and-Ga co-doped ZnO films,Magnetron sputtering
更新于2025-09-23 15:19:57
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Dynamics of Instability in Plasmonic Response of Nanostructured Gold Thin Films on Ambient Ageing
摘要： Instability in the plasmonic response of nanostructured gold (Au) thin films on ambient ageing has been investigated. Different types of Au nanostructures (island, percolated, and continuous thin film) are obtained at the early stage of thin film growth by variation in film thickness using sputtering technique. Absorbance spectra of as-deposited island Au film shows a systematic blue-shift in the localized surface plasmon resonance (LSPR) peak position on ageing. The rate of blue-shift in the LSPR peak position is fitted with single-exponential decay function to analyze the dynamics of the plasmonic response. The as-deposited percolated Au film displays a transformation of broadened plasmonic response into a wavelength independent absorbance profile on ageing. The immersion of a new plasmonic band in the absorbance spectra is noted for continuous Au thin film on ageing. The change in plasmonic responses of nanostructured Au thin films on ambient ageing is found to be directly correlated with the re-organization of the surface morphology. Finally, ageing-induced solid-state dewetting and crystallization are found to be the main responsible processes of the underlying mechanism for morphological re-organizations, leading to change in the plasmonic response of the nanostructured Au thin films.
关键词： X-ray reflectivity,Grazing incidence X-ray diffraction,Localized surface plasmon resonance,Thin film ageing,Transmission electron microscopy
更新于2025-09-23 15:19:57
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Controlled Sputtering Pressure on High-Quality Sb2Se3 Thin Film for Substrate Configurated Solar Cells
摘要： Magnetron sputtering has become an effective method in Sb2Se3 thin film photovoltaic. Research found that post-selenization treatments are essential to produce stoichiometric thin films with desired crystallinity and orientation for the sputtered Sb2Se3. However, the influence of the sputtering process on Sb2Se3 device performance has rarely been explored. In this work, the working pressure effect was thoroughly studied for the sputtered Sb2Se3 thin film solar cells. High-quality Sb2Se3 thin film was obtained when a bilayer structure was applied by sputtering the film at a high (1.5 Pa) and a low working pressure (1.0 Pa) subsequently. Such bilayer structure was found to be beneficial for both crystallization and preferred orientation of the Sb2Se3 thin film. Lastly, an interesting power conversion efficiency (PCE) of 5.5% was obtained for the champion device.
关键词： Sb2Se3,magnetron sputtering,substrate configuration,post-selenization,working pressure,thin film solar cell
更新于2025-09-23 15:19:57
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Laser-Induced Graphene Paper Heaters with Multimodally Patternable Electrothermal Performance for Low-Energy Manufacturing of Composites
摘要： Low-energy manufacturing of polymeric composites through two-dimensional electrothermal heaters is a promising strategy over traditional autoclave and oven. Laser induced graphene paper (LIGP) is a recent emergent multifunctional material with merits of one-step computer aided design and manufacturing (CAD/CAM) as well as flexible thin nature. To fully explore its capabilities of in situ heating, herein, we adventurously propose and investigate the customizable manufacture and modulation of LIGP enabled heaters with multimodally patternable performance. Developed by two modes (uniform & nonuniform) of laser processing, the LIGP heaters (LIGP-H) show distinctively unique characteristics, including high working range (> 600 °C), fast stabilization (< 8 s), high temperature efficiency (~370 °C·cm2/W), and superb robustness. Most innovatively, the non-uniform processing could section LIGP-H into subzones with independently controlled heating performance, rendering various designable patterns. The above unique characteristics guarantee the LIGP-H highly reliable for in situ curing composites with flat, curve and even inhomogeneous structures. With enormous energy-saving (~85%), superb curing accuracy, and comparable mechanical strength, the proposed device is advantageous for assuring high-quality and high-efficient manufacturing.
关键词： polymeric composites,graphene papers,thin film heaters,flexible electronics,laser-induced graphene
更新于2025-09-23 15:19:57
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Quasi-Vertically-Orientated Antimony Sulfide Inorganic Thin-Film Solar Cells Achieved by Vapor Transport Deposition
摘要： The one-dimensional photovoltaic absorber material Sb2S3 requires crystal orientation engineering to enable efficient carrier transport. In this work, we adopted a vapor transport deposition (VTD) method to fabricate vertically aligned Sb2S3 on a CdS buffer layer. Our work shows that such a preferential vertical orientation arises from the sulfur deficit of the CdS surface which creates a beneficial bonding environment between exposed Cd2+ dangling bonds and S atoms in the Sb2S3 molecules. The CdS/VTD-Sb2S3 interface recombination is suppressed by such properly aligned ribbons at the interface. Compared with typical [120]-oriented Sb2S3 films deposited on CdS by rapid thermal evaporation (RTE) method, the VTD-Sb2S3 thin film is highly [211]- and [121]- oriented and the performance of the solar cell is increased considerably. Without using any hole transportation layer, a conversion efficiency of 4.73% is achieved with device structure of ITO/CdS/Sb2S3/Au. This work provides a potential way to acquire vertical aligned thin films on different buffer layers.
关键词： inorganic device,Sb2S3 solar cell,Vapor transport deposition,thin film,vertical growth
更新于2025-09-23 15:19:57