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Electromagnetic engineered mechanical trapping potential and the conversion in optomechanics
摘要： The manipulation of mechanical response in optomechanical system allows observation of quantum behavior by cooling a mechanical resonance to its quantum mechanical ground state, and it relies on the effective tuning of trapping potentials. In this work, we investigate the conversion process between radiation pressure and mechanical trapping potential which is engineered by the optical field in an optomechanical system. Moreover, a set of trapping potentials could be achieved by tuning the system, such as detuning, pumping power and decay rates. Specifically, the speed of conversion between different potential states is studied which approaches the megahertz level.
关键词： optomechanical system,conversion,Mechanical trapping potential
更新于2025-09-23 15:21:21
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Linear and non linear optical properties of Sb2Se3 thin films elaborated from nano-crystalline mechanically alloyed powder
摘要： Sb2Se3 powder is achieved by mechanical milling of Sb and Se elements. X-ray diffraction analysis indicated the formation of Sb2Se3 orthorhombic phase. The latter finding is confirmed by both X-ray photoelectron spectroscopy characterization and Raman spectroscopy. Magnetic measurement revealed the ferromagnetic character of Sb2Se3 powder. Thin films were obtained by thermal deposition using Sb2Se3 powder as a precursor. Optical measurements carried out on thin films showed a high absorption coefficient and a direct band gap of 1.61 eV. The material has then potential application in photovoltaic conversion. Thin film refractive index dispersion (n) obeys Cauchy dispersion equation. n is investigated and found to comply with Wemple–DiDomenico single oscillator dispersion model. The energy E0 of the oscillator and Ed dispersion energy are derived from the refractive index investigation. Spitzer–Fan model exploitation was allowed to derive the high-frequency dielectric constant ε∞ and the carrier density N/m* ratio. Additionally, Verdet constant V is determined based on the refractive index dispersion study. Furthermore, the nonlinear susceptibility χ(3) as well as nonlinear refractive index are determined for Sb2Se3 thin films. The nanostructure of the material is likely responsible not only for the high nonlinear characteristics but also for the low magnetic character in Sb2Se3.
关键词： Nonlinear optical properties,Optical properties,Thermal deposition,Sb2Se3,Mechanical milling
更新于2025-09-23 15:21:21
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Effect of Deposition Pressure, Nitrogen Content and Substrate Temperature on Optical and Mechanical Behavior of Nanocomposite Al-Si-N Hard Coatings for Solar Thermal Applications
摘要： Hard and optically transparent nanocomposite Al-Si-N thin films were deposited using DC magnetron sputtering at different process parameters. There was a significant effect of these parameters on the film properties affecting its mechanical and optical behavior. The nitrogen content or pressure, deposition pressure and substrate temperature strongly influence the phase formation which governs the hardness and optical transparency of the coating. Hardness was measured between 18 and 30 GPa. The band gap could be varied in the range of 3.8-4.2 eV by varying nitrogen pressures in the chamber during deposition. The films showed (0-80)% transparency in UV and visible region depending on the sputtering conditions.
关键词： mechanical behavior,optical coating,nanocomposite hard coatings
更新于2025-09-23 15:21:21
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Comparison of the Physicochemical Properties of TiO2 Thin Films Obtained by Magnetron Sputtering with Continuous and Pulsed Gas Flow
摘要： In this paper, a comparison of TiO2 thin ?lms prepared by magnetron sputtering with a continuous and pulsed gas ?ow was presented. Structural, surface, optical, and mechanical properties of deposited titanium dioxide coatings were analyzed with the use of a wide range of measurement techniques. It was found that thin ?lms deposited with a gas impulse had a nanocrystalline rutile structure instead of ?brous-like anatase obtained with a continuous gas ?ow. TiO2 thin ?lms deposited with both techniques were transparent in the visible wavelength range, however, a much higher refractive index and packing density were observed for coatings deposited by the pulsed gas technique. The application of a gas impulse improved the hardness and scratch resistance of the prepared TiO2 thin ?lms.
关键词： optical properties,scratch resistance,thin ?lms,gas impulse magnetron sputtering,microstructure,hardness,surface properties,mechanical properties,TiO2
更新于2025-09-23 15:21:21
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Tuning the Cross-Linker Crystallinity of a Stretchable Polymer Semiconductor
摘要： The cross-linking of conjugated polymers has been demonstrated to be an effective strategy to improve its elastic properties to give deformable semiconductors for plastic electronics. While there have been extensive studies of the structural requirements of the polymer host for good film ductility, no work to date has focused on the relevance of the structural design or chemistry of these cross-linker additives. In this study, urethane groups and tertiary carbon atoms are inserted into the alkyl backbone of perfluorophenyl azide-based cross-linkers to investigate the importance of cross-linker crystallinity with respect to polymer morphology and hence mechanical and electrical properties. Linear cross-linkers with hydrogen bonding from urethane groups readily phase separate and recrystallize in the polymer network to form cross-linked domains that obstruct the strain distribution of the polymer film. Branch cross-linkers with tertiary carbon on the other hand form an evenly cross-linked network in the polymer blend stemming from excellent miscibility and show a 4-fold increase in fracture strain. Furthermore, a stable hole mobility of 0.2 cm2 V?1 s?1 is achieved up to ε = 100%, and a stable hole mobility of 0.1 cm2 V?1 s?1 after 2000 cycles of ε = 25% on fully stretchable organic field-effect transistors.
关键词： cross-linking,deformable semiconductors,cross-linker crystallinity,electrical properties,polymer morphology,elastic properties,plastic electronics,conjugated polymers,mechanical properties
更新于2025-09-23 15:21:21
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Quasi-1D TiS <sub/>3</sub> Nanoribbons: Mechanical Exfoliation and Thickness-Dependent Raman Spectroscopy
摘要： Quasi-one-dimensional (quasi-1D) materials enjoy growing interest due to their unusual physical properties and promise for miniature electronic devices. However, the mechanical exfoliation of quasi-1D materials into thin flakes and nanoribbons received considerably less attention from researchers than the exfoliation of conventional layered crystals. In this study, we investigated the micromechanical exfoliation of representative quasi-1D crystals, TiS3 whiskers, and demonstrate that they typically split into narrow nanoribbons with very smooth, straight edges and clear signatures of 1D TiS3 chains. Theoretical calculations show that the energies required for breaking weak interactions between the two-dimensional (2D) layers and between 1D chains within the layers are comparable and, in turn, are considerably lower than those required for breaking the covalent bonds within the chains. We also emulated macroscopic exfoliation experiments on the nanoscale by applying a local shear force to TiS3 crystals in different crystallographic directions using a tip of an atomic force microscopy (AFM) probe. In the AFM experiments, it was possible to slide the 2D TiS3 layers relative to each other as well as to remove selected 1D chains from the layers. We systematically studied the exfoliated TiS3 crystals by Raman spectroscopy and identified the Raman peaks whose spectral positions were most dependent on the crystals’ thickness. These results could be used to distinguish between TiS3 crystals with thickness ranging from one to about seven monolayers. The conclusions established in this study for the exfoliated TiS3 crystals can be extended to a variety of transition metal trichalcogenide materials as well as other quasi-1D crystals. The possibility of exfoliation of TiS3 into narrow (few-nm wide) crystals with smooth edges could be important for the future realization of miniature device channels with reduced edge scattering of charge carriers.
关键词： transition metal trichalcogenides,quasi-one-dimensional materials,scanning near-field optical microscopy,Raman spectroscopy,mechanical exfoliation
更新于2025-09-23 15:21:21
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Realization of ultra-high quality InGaN platelets to be used as relaxed templates for red microLEDs
摘要： In this work, arrays of predominantly relaxed InGaN platelets with indium contents of up to 18%, free from dislocations and offering a smooth top c-plane, are presented. The InGaN platelets are grown by metal-organic vapor phase epitaxy on a dome-like InGaN surface formed by chemical mechanical polishing of InGaN pyramids defined by six equivalent {1011} planes. The dome-like surface is flattened during growth, through the formation of bunched steps, which are terminated when reaching the inclined {1011} planes. The continued growth takes place on the flattened top c-plane with single bilayer surface steps initiated at the six corners between the c-plane and the inclined {1011} planes, leading to the formation of high quality InGaN layers. The top c-plane of the as-formed InGaN platelets can be used as a high quality template for red microLEDs.
关键词： selective area growth,InGaN,template,chemical mechanical polishing,vapor phase epitaxy,microLEDs
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) - The Impact of Cold Temperature Exposure in Mechanical Durability Testing of PV Modules
摘要： Existing mechanical durability testing sequences typically perform mechanical loading prior to environmental exposures such as thermal cycling or humidity freeze. Recent work has shown that the fracture strength of silicon solar cells can reduce after exposure to temperatures below -20°C. In an effort to better evaluate modules with respect to cell crack durability, we explore the use of a single thermal cycle prior to mechanical loading. Modules were exposed to a static front-side load before and after exposure to a single thermal cycle and were characterized with current-voltage measurements and electroluminescence imaging. The results show a significant increase in the number of cell cracks that are generated at a given load after a single cold exposure. We explore how this can be used to further optimize the qualification test sequence for mechanical durability.
关键词： cell fracture,photovoltaic modules,mechanical durability,reliability,silicon
更新于2025-09-23 15:21:01
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Achieving strong friction lap joints of carbon-fiber reinforced plastic and metals by modifying metal surface structure via laser-processing pretreatment
摘要： Strong dissimilar joints of metals and carbon fiber reinforced plastic (CFRP) are highly demanded for the lightweight design in many fields, which, however, are rather challenging to achieve directly via welding. In this study, 5052 Al alloy and plain carbon steel were first pretreated by a laser-processing method to create rather coarse porous metal surfaces, which were then welded to polyamide 6 based CFRP using friction lap joining. The maximum tensile shear force of the dissimilar joints of CFRP-Al alloy and CFRP-steel achieved 4.9 kN, and 3.9 kN, respectively, and the joint efficiency achieved 78% and 62%, respectively, which were more than three times as those of the CFRP- as-received metal joints. This is the first report on the strengthening of the metal-CFRP friction based joints via the assisting laser treatment technique. The significant improvement of the joint strength could be attributed to a great increase of the mechanical anchors and the chemical bonding area at the metal-CFRP interface.
关键词： Metal,Laser processing,Mechanical interlocking,Dissimilar joining,Friction stir welding,Carbon-fiber reinforced plastic
更新于2025-09-23 15:21:01
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Manufacturing profile-free copper foil using laser shock flattening
摘要： Copper foil is a key material of printed circuit boards and plays an important role in the conductance of electric circuits and interconnection of electronic components. When high-frequency signals were transmitted in rough copper foil wires, the conductor resistance, wire loss, and signal loss increased because of the skin effect. To reduce the negative influence of the skin effect and improve the quality of the copper foil, a laser shock flattening (LSF) method was proposed to manufacture profile-free copper foil with high performance. It was concluded that the better flattening effect for large-area profile-free copper foil could be achieved at a pulse energy of 0.25 J and an overlap rate of 25%, and its surface roughness decreased by 67.0% from 52.1 nm to 17.2 nm. Subsequently, to determine the mechanism for the flattened deformation of copper foil induced by LSF, the microstructures of the copper foil before and after flattening were characterised using transmission electron microscopy. A higher dislocation density and a few deformation twins were found in the profile-free copper foil. Ultimately, nano-indentation, micro-tensile, and electrochemical corrosion tests indicated that the mechanical properties and corrosion resistance of the copper foil were significantly improved by LSF. This technique would enable the successful fabrication of large-area profile-free copper foil with high performance for the emerging applications of ultra-high-frequency signal communication and printed circuit board manufacture.
关键词： Corrosion resistance,Mechanical properties,Flattened deformation mechanism,Microstructures,Laser shock flattening,Profile-free copper foil
更新于2025-09-23 15:21:01