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Ultrasonic spray pyrolyzed copper oxide and copper-aluminum oxide thin films: optical, structural and electronic properties
摘要： A study of the structural, electrical and optical properties of copper oxide and copper-aluminum oxide thin films deposited by ultrasonic spray pyrolysis is presented in this work. On one hand copper oxide films were deposited at working temperatures in the range from 300 °C to 500 °C. These films present a mixture of Cu2O and CuO phases, CuO phase being more abundant at higher temperatures; all samples present p-type conductivity. On the other hand, copper-aluminum oxide samples were deposited at 350 °C but with different copper-aluminum ratios in the start solution (0, 12.5, 25, 50, 100, and 200 at.%). The films present a mixture of Cu2O and Al2O3 phases, being the Cu2O the most abundant and becoming amorphous as aluminum concentration rises. Electrical characterization indicates that electronic conductivity depends on the amount of Cu2O, while ionic conductivity increases with aluminum concentration. Aluminum concentration also provokes a shift in the valence band towards lower binding energies, as well as an increase in the optical band gap (from 2.6 to 3.7 eV). Upon a thermal annealing at 800 °C the samples turned to CuAl2O4 spinel structure.
关键词： Optical characterization,Electrical characterization,Semiconducting copper-aluminum compounds,Spray pyrolysis
更新于2025-09-23 15:21:01
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The effect of Zn3N2 phase decomposition on the properties of highly-doped ZnO: Al, N films
摘要： Study of Al-N simultaneous doping and thermal annealing influence on the properties of ZnO films is very important for achievement as p-type conductivity in the films as for improvement the performance of ZnO-based ultraviolet detectors. Highly-doped ZnO:Al,N films containing the Zn3N2 phase (ZnO:Al,N-Zn3N2) were grown on Si substrates by magnetron sputtering using a layer-by-layer growth technique. Our work presents a comparative study of the structure, optical and electronic properties of highly-doped as-grown and annealed ZnO:Al,N films. It was shown that the thermal annealing of ZnO:Al,N-Zn3N2 film at atmospheric conditions allows to decompose the Zn3N2 phase. The features of this phenomena on the properties of ZnO:Al,N films were investigated and discussed in detail by using X-ray diffraction, energy dispersive X-ray analysis, Raman scattering, photoluminescence, X-ray photoelectron spectroscopy and X-ray emission spectroscopy.
关键词： Radio-frequency magnetron sputtering,Zinc oxide,Nitrogen-aluminum doping,Photoluminescence,X-ray photoelectron spectroscopy,Thin films,X-ray diffraction,Raman scattering
更新于2025-09-23 15:21:01
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Analysis of different conductive pastes to form the contact with the boron back surface field in PERT silicon solar cells
摘要： The industrial production of solar cells of the PERC family is growing, because the potential to increase the efficiency due to the passivation of the rear face. The PERT solar cell is a cost-effective structure of the PERC configurations. The goal of this paper is to analyze the influence in the electrical parameters of different metal pastes used to form the contact with the boron back surface field of PERT solar cells passivated with silicon dioxide on both sides and developed with a cost-effective process. The boron doped BSF and phosphorus emitter were carried out with reduction of steps. Solar cells were processed with three different conductive pastes: (1) an aluminum paste (PV381), (2) a silver/aluminum paste (PV3N1) and (3) a silver paste (PV51G), with different viscosity and solids content. The pastes were produced by DuPont. The PV381 and PV3N1 pastes produced solar cells with the efficiency of 16.2% and 15.9%, respectively. The higher open circuit voltage was achieved with the aluminum paste, indicating that this paste is more effective to produce the selective back surface field. The PV51G paste is not suitable to form the rear contact.
关键词： aluminum and silver/aluminum pastes,boron back surface field,PERT silicon solar cells
更新于2025-09-23 15:19:57
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Effect of laser shock peening on mechanical and microstructural aspects of 6061-T6 aluminum alloy
摘要： Laser shock peening (LSP) of 6061-T6 aluminum alloy was performed and parametric effects post LSP on mechanical aspects and microstructural evolution are meticulously studied using various means of characterization techniques such as residual stress analysis, surface roughness, Vickers microhardness, tensile testing, X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and electron back scattered diffraction (EBSD). Work hardened layer of ~1500 μm depth is obtained with significant improvement in cross-sectional microhardness up to 33.04%. Beneficial compressive residual stress of maximum magnitude up to -273 MPa was induced in laser peened specimens concentrating its overall effect around the depth of 100 μm along the effective depth region. Second phase Mg5Si6 (β?) precipitates were observed post LSP while analyzing XRD profiles along with the peak broadening and peak shifting towards higher 2θ angle justifying the results obtained in microhardness profile. High angle grain boundaries (HAGBs) fraction was increased in LSPed specimens and its effect is noticed in residual stress profile. Mg5Si6 (β?) precipitates are attributed as contributing precipitates in improving the mechanical properties of LSPed specimens along with the dense dislocation density caused by severe plastic deformation during LSP. The collective contribution of strain hardening, second phase precipitates, peak broadening, dislocation density and increased fraction of HAGBs is observed in mechanical and microstructural aspects of LSPed specimens. The results are discussed in detailed and are strongly correlated with each other.
关键词： EBSD,Aluminum alloy,cosα method,TEM,XRD,Laser shock peening
更新于2025-09-23 15:19:57
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Fabrication of AlN/GaN MSM photodetector with platinum as schottky contacts
摘要： The epitaxial aluminium nitride (AlN) layer was fabricated on a silicon (111) substrate by solid phase radio frequency (RF) MBE The samples morphological characteristic was successfully studied by ?eld emission SEM. Low photo-response of the hetero-structure layers is one of the main obstacles in order to fabricate a high performance of photodetector device. The platinum contacts on AlN/GaN metal-semiconductor-metal (MSM) photodetector were formed by RF sputtering machine. The conductivity behaviours, Schottky barrier height (SBH), photo-responses of the device were examined by source meter measurement. The SBH values of photo-device sensing were calculated as 0.488 eV and 0.479 eV for dark current and photo current, respectively. Good response times of the device were recorded as 21.48 ms and 12.69 ms for the bias voltage of 1 volt.
关键词： AlN,photodetector,aluminum nitride
更新于2025-09-23 15:19:57
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Vapor plume and melted zone behavior during dissimilar laser welding of titanium to aluminum alloy
摘要： The present study deals with continuous Yb:YAG laser welding of pure titanium to aluminum alloy A5754 performed with different beam offsets to the joint line. Spectroscopic and morphological characterization of vapor plume exiting the keyhole was combined with post-mortem observation and energy-dispersive X-ray spectroscopy (EDX) analysis of the welds. The laser beam centered on the joint line resulted in periodic transversal inclination of a vapor jet on the aluminum side associated with a local increase of melt width and an intense spatter formation. Such behavior can be attributed to the instability of the keyhole wall from the aluminum side. The beam offset on the titanium side led to the stabilization of vapor plume, the attenuation of spattering, and a minimal mixing between the two liquid metals. On the contrary, the beam offset on the aluminum side produced a violent formation of spatters and a highly unstable, diffuse vapor jet. In this case, the liquid metals underwent a violent mixing that was progressively reduced along with the decrease in quantity of melted Ti. The observed spectral regions contained the emission peaks of neutral Ti and Mn. Very few emission lines of Al were observed, because they require higher excitation energies compared to Ti and Mn. Boltzmann linearization using Ti emission peaks allowed the estimation of vapor temperature to be between 5000 and 6000 K, except for the welds with the beam offset on Al.
关键词： titanium,Laser,aluminum,emission spectroscopy,dissimilar welding
更新于2025-09-23 15:19:57
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Plasmonic Fano Resonance in Homotactic Aluminum Nanorod Trimer: the Key Role of Coupling Gap
摘要： Recently, the Fano effect of aluminum nanostructures has attracted a lot of attentions in several detector and sensor applications, but the role of coupling gap in it remains unintuitive. In this paper, a homotactic aluminum rod trimer (HART) is designed to form the plasmonic Fano resonances and visualize the important role of coupling gap size. The plasmon hybridization model and far field images were used to qualitatively describe the formation mechanism of Fano resonance. The simulation results intuitively show that the Fano dip of HART with a smaller coupling gap size has a higher red-shift speed when increasing the refractive index of surrounding environment or the length of HART with a fixed axial ratio (LS/LL = 0.6). Our study provides the insights to the key role of coupling gap in the performance of Fano structures.
关键词： Fano resonance,Aluminum nanorods,Far field,Plasmon,Coupling gap
更新于2025-09-23 15:19:57
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Interactive tissue reactions of 1064a??nm focused picoseconda??domain laser and dermal cohesive polydensified matrix hyaluronic acid treatment in in vivo rat skin
摘要： Background: Picosecond-domain laser treatment using a microlens array (MLA) or a diffractive optical element (DOE) generates micro-injury zones in the epidermis and upper dermis. Objective: To investigate interactive tissue reactions between MLA-type picosecond laser pulses and cohesive polydensified matrix hyaluronic acid (CPMHA) filler in the dermis. Methods: In vivo rats with or without CPMHA pretreatment were treated with a 1064-nm picosecond-domain neodymium:yttrium-aluminum-garnet (Nd:YAG) laser using an MLA or DOE. Skin samples were obtained at post-treatment days 1, 10, and 21 and histologically and immunohistochemically analyzed. Results: Picosecond-domain Nd:YAG laser treatment with an MLA-type or a DOE-type handpiece generated fractionated zones of pseudo-cystic cavitation along the lower epidermis and/or upper papillary dermis at Day 1. At Day 21, epidermal thickness, dermal fibroblasts, and collagen fibers had increased. Compared to CPMHA-untreated rats, rats pretreated with CPMHA showed marked increases in fibroblasts and collagen fibers in the papillary dermis. Immunohistochemical staining for the hyaluronic acid receptor CD44 revealed that MLA-type picosecond laser treatment upregulated CD44 expression in the basilar epidermis and dermal fibroblasts. Conclusions: We suggest that the hyaluronic acid-rich environment associated with CPMHA treatment may enhance MLA-type picosecond-domain laser-induced tissue reactions in the epidermis and upper dermis.
关键词： laser,neodymium-doped yttrium aluminum garnet,cohesive polydensified matrix hyaluronic acid,laser-induced tissue breakdown,CD44,picosecond
更新于2025-09-23 15:19:57
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Laser Powder Bed Fusion of high strength aluminum
摘要： Demands for high strength aluminum alloys processed by Laser Powder Bed Fusion (LPBF) are high and keep rising. However, expensive new alloy compositions or crack formation in existing alloys hinder its wide applicability. It is known from recent work that addition of grain refiners leads to a fine grain structure enabling crack-free, high strength aluminum LPBF parts. In this research, 1wt% of Zr was added to Al7050. Furthermore, an excess of Zn was provided in the powder material to compensate for Zn losses during LPBF and to maintain the Mg:Zn ratio required for formation of strong and coherent MgZn2 precipitates. After a solution and aging heat treatment, the newly developed alloy has an ultimate tensile strength of 500MPa and Vickers micro-hardness of 200Hv-0.5kg. Although the elongation at break of the resulting parts is limited, this research shows promising results for future alloy design of affordable high strength aluminum alloys to be processed by LPBF.
关键词： grain refinement,aluminum,Laser Powder Bed Fusion,cracks
更新于2025-09-23 15:19:57
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An investigation of aluminum nitride thin films patterned by femtosecond laser
摘要： In this study, a femtosecond laser etching method is proposed to pattern an aluminum nitride (AlN) ?lm, grown by metal-organic chemical vapor deposition on sapphire. Via control of typical pulse energies, the designed pattern was precisely written in the AlN ?lm. The morphology of the patterned structures was characterized using a three-dimensional laser scanning confocal microscope and a scanning electron microscope; crystalline quality and ?lm strain were analyzed using a Raman spectrometer and a transmission electron microscope. The results indicate that consistent morphologies were achieved with only slight changes to the crystalline quality. The tensile stress of the AlN ?lm was released, and the ?lm surface was slightly compressed after laser patterning. Thus, femtosecond etching has the potential to be an in situ patterning method during ?lm growth.
关键词： film strain,patterning,crystalline quality,femtosecond laser,aluminum nitride,thin films
更新于2025-09-23 15:19:57