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- 摘要
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Effect of gas phase temperature on InGaN grown by metalorganic vapor phase epitaxy
摘要： Wafer trays with different gaps (the distance between the top of the pocket and the bottom of the wafer) were used to grow InGaN/GaN multiple quantum wells (MQWs) in a horizontal metalorganic vapor phase epitaxy (MOVPE) reactor. The numerical reactor simulation revealed that at the similar surface temperature the gas phase temperature around the wafer increases due to an increased wafer tray temperature. This increased gas phase temperature is expected to increase the effective V/III ratio by enhanced NH3 decomposition. Photoluminescence (PL) intensities of long-wavelength MQWs increased at the same indium content by the enhanced gas phase temperature, while the emission became narrow. This is related to a smoother topography at higher gas phase temperatures.
关键词： A3. Metalorganic vapor phase epitaxy,B2. Semiconducting III-V materials,A1. Crystal morphology,B1. Nitride
更新于2025-09-04 15:30:14
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Exploring the photoelectrocatalytic behavior of free-standing TiO2 nanotube arrays on transparent conductive oxide electrodes: Irradiation direction vs. alignment direction
摘要： Although one-dimensional TiO2 nanotube arrays (TNA) grown on Ti substrates via electrochemical anodization are extensively studied in photoelectrochemistry, the photo(electro)catalytic activity of TNA detached from the Ti substrates remains unexplored. Herein, we synthesize TNA samples with various pore sizes (40?100 nm) and tube lengths (4?15 μm) via two-step electrochemical anodization, and transfer them to transparent conducting oxide (i.e. fluorine-doped tin oxide; FTO) substrates in normal (n) alignment (front plane outward) and reverse (r) alignment (backplane outward). The front and back planes of the as-fabricated TNA film are the same based on X-ray diffraction (anatase structure), X-ray photoelectron spectroscopy (Ti and O), and UV-vis transmittance data, though the tubes are open in the front and closed in the back. Regardless of the direction of irradiation (SE: FTO → TNA vs. EE: TNA → FTO), longer tubes generate a higher photocurrent (Iph) due to the large light absorption. However, for the same alignment of TNA (either n- or r-TNA), SE irradiation leads to a very large Iph (e.g., nSE > nEE), whereas n-TNA consistently generates a larger Iph than r-TNA for a given irradiation direction (i.e., n > r). The photocatalytic decomposition of phenol follows the same tendency (n > r); however, the Faraday efficiency (based on the photocharge) is higher with EE (nEE 28%, rEE 20%) than SE (rSE 11%, nSE 7%) irradiation. These photoelectrochemical and photocatalytic behaviors are explained in terms of charge carrier generation (FTO/TNA vs. TNA/solution), dissimilar charge carrier transfer pathways (e? transfer through tube framework vs. h+ transfer via radial direction), and charge injection at the tube (open vs. clogged tube mouth)/solution interface. The time-resolved photoluminescence (TRPL) emission and incident photon-to-current efficiency (IPCE) are also studied to gain insight into the charge transfer kinetics.
关键词： Photocatalysis,Anodization,Charge transfer,Photoelectrochemistry,Morphology
更新于2025-09-04 15:30:14
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Elemental silver nano-sized crystals: various geometric forms and their specific growth parameters
摘要： The data have been systematized and generalized on the specific synthesis of elemental silver nano-sized crystals (Ag-NC) having the forms of various geometric bodies (pseudo spherical, prismatic, cubic, trigonal-pyramidal, etc.), obtained by various chemical, physicochemical and biological methods. It has been noted, that the form of the synthesized Ag-NC can be controlled by changing the thermodynamic and kinetic parameters at each key stage of the synthesis (nucleation, seeding, and growth). Moreover, the size range of spherical and cubic silver nanocrystals can be influenced by either physical, chemical or biological methods during the synthesis, but such forms as nanorods, nanowires and nanobars can only be synthesized by chemical or physical methods at the present time. The review covers articles comprehensively mainly published in the last 20 years.
关键词： photography,Silver nano-crystals,geometric form,crystal morphology,growth parameters
更新于2025-09-04 15:30:14
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[IEEE 2018 2nd IEEE Advanced Information Management,Communicates, Electronic and Automation Control Conference (IMCEC) - Xi'an (2018.5.25-2018.5.27)] 2018 2nd IEEE Advanced Information Management,Communicates,Electronic and Automation Control Conference (IMCEC) - Ice Detection of Transmission Line Based on Image Fusion
摘要： In order to maintain the safe and stable operation of the power system, early detection and early warning of the icing on transmission lines and avoiding the occurrence of ice-coating accidents, a method based on digital image processing is proposed to determine the icing status of transmission lines. In the process of icing detection of transmission lines, the quality of images of icing transmission lines from the natural environment is poor due to objective factors, and the present detection methods are difficult to accurately extract the boundaries from the low-quality icing images of transmission lines. In response to this problem, a method based on image fusion technology is proposed to determine the icing condition of transmission line. The transmission line is image pre-processing, wavelet transform detected through detection, morphological processing, line extraction and weighted fusion, after that, the ice thickness of transmission line is calculated by pixel comparison. The model was simulated in MATLAB and compared with the results of other existing edge detection methods, showing that the edge details obtained by this method are clearer and the ice thickness measurement is more accurate.
关键词： image fusion,wavelet transform,line extraction,detection of icing on transmission line,morphology,edge detection
更新于2025-09-04 15:30:14
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Influence of the Conditions of the Chemical Bath Deposition of Thin ZnSe Films on Their Morphology and Internal Mechanical Stresses
摘要： ZnSe films up to 2300 nm thick on glass-ceramic supports were prepared by chemical bath deposition in the ZnCl2–Na2EDTA–NaOH–NH2OH·HCl system using sodium selenosulfate as a chalcogenizer. The reflections observed in the X-ray diffraction patterns correspond to the ZnSe (stilleite) phase of cubic (space group F43m) structure with a = 5.610 ± 0.002 ?. As shown by electron-microscopic examination, ZnSe films consist of globular formations tightly adjoining to each other with the mean size of 250–400 nm depending on the deposition conditions. Elemental EDX analysis shows that the films contain, on the average, 43.68 at. % Zn, 30.50 at. % Se, and 25.82 at. % O, with the oxygen concentration somewhat decreasing at a depth of 30 nm. The internal mechanical compression stresses caused by the difference in the thermal expansion coefficients of the ZnSe film and glass-ceramic support were calculated; these stresses depend on the film thickness and at ~1040 nm reach –30.62 kN m–2. The results obtained make it possible to exclude film discontinuities, which can appear with increasing film thickness in preparation of precursor layers, and to choose the optimum support material.
关键词： chemical bath deposition,microstructure,internal mechanical stresses,film morphology,zinc selenide,films,sodium selenosulfate
更新于2025-09-04 15:30:14
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Micro Structural and Optical Properties of Ferrous Selenide Thin Films and Its Characterization
摘要： Ferrous Selenide (FeSe) thin films were prepared onto glass substrate by Electron beam evaporation technique. X-Ray Diffractometer analyses showed that highly c-axis oriented and high-quality films were obtained on various annealing temperatures of 100°C, 200°C and 300°C respectively. From Scanning Electron Microscopy and its Elemental analysis of all the films showed low-temperature structural phase transition at different annealing temperatures of RT, 100°C, 200°C and 300°C respectively. The optical studies of FeSe thin film on glass was found most different from all the others, and its bandgap decreases from 2.85 eV to 2.75 eV for different annealing temperatures of the thin films. Optical analysis is demonstrated that Ferrous (Fe) and Selenide (Se) are homogeneously distributed in the film. Atomic Force Microscopy (AFM) and its 2D and 3D analyses were found that microstructure of FeSe thin films.
关键词： Morphology,Structural,Optical,FeSe thin films
更新于2025-09-04 15:30:14
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Structural, Linear and Third Order Nonlinear Optical Properties of Sol-Gel Grown Ag-CdS Nanocrystalline Thin Films
摘要： Pure and Ag doped CdS nanocrystalline ?lms with different Ag doping concentrations were successfully grown on glass substrates by a sol-gel spin coating method. Ag doping was performed using silver acetate aqueous solution with 0.01, 0.02 and 0.03 M concentrations via ion exchange. The in?uences of Ag doping on structural, vibrational, morphological, linear and third order nonlinear optical properties of CdS nanocrystalline ?lms were studied. The x-ray diffraction patterns of the ?lms exhibited a broad peak centered at an angle 2h = 26.5(cid:2) along the (111) plane, which con?rms the cubic structure and formation of nanocrystalline ?lms. Raman spectra of ?lms demonstrate a shift in longitudinal optical phonon vibrations as compared to the bulk counterpart. Pure CdS ?lm shows high transmittance (83%) in the visible and near infrared (NIR) regions. With Ag doping, a signi?cant red shift in the band edge and reduction in the transmittance of the ?lms in visible and NIR regions were observed. However, the ?lms doped with Ag showed appreciable transmittance in visible region for window layer applications. A signi?cant effect on optical parameters such as absorption index, refractive index, and optical dielectric constant was observed after Ag doping. The nonlinear optical properties of ?lms were enhanced with incorporation of Ag atoms into the CdS binary system. The values of nonlinear optical susceptibility v(3) and refractive index n2 were found to increase with increasing Ag concentration and were estimated to be in the range of 2.92 9 10(cid:2)10 (cid:2) 1910(cid:2)7 esu and 1.00 9 10(cid:2)9 2.00 9 10(cid:2)7 esu, respectively. These values suggest that these ?lms can be potential candidates for nonlinear optical device applications.
关键词： structural properties,optical properties,surface morphology,Ag-CdS,Raman spectroscopy
更新于2025-09-04 15:30:14
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Polymer morphology and interfacial charge transfer dominate over energy-dependent scattering in organic-inorganic thermoelectrics
摘要： Hybrid (organic-inorganic) materials have emerged as a promising class of thermoelectric materials, achieving power factors (S2σ) exceeding those of either constituent. The mechanism of this enhancement is still under debate, and pinpointing the underlying physics has proven dif?cult. In this work, we combine transport measurements with theoretical simulations and ?rst principles calculations on a prototypical PEDOT:PSS-Te(Cux) nanowire hybrid material system to understand the effect of templating and charge redistribution on the thermoelectric performance. Further, we apply the recently developed Kang-Snyder charge transport model to show that scattering of holes in the hybrid system, de?ned by the energy-dependent scattering parameter, remains the same as in the host polymer matrix; performance is instead dictated by polymer morphology manifested in an energy-independent transport coef?cient. We build upon this language to explain thermoelectric behavior in a variety of PEDOT and P3HT based hybrids acting as a guide for future work in multiphase materials.
关键词： polymer morphology,charge transport,PEDOT:PSS,thermoelectric materials,hybrid materials
更新于2025-09-04 15:30:14
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Faceting and metal-exchange catalysis in (010) β-Ga <sub/>2</sub> O <sub/>3</sub> thin films homoepitaxially grown by plasma-assisted molecular beam epitaxy
摘要： We here present an experimental study on (010)-oriented β-Ga2O3 thin films homoepitaxially grown by plasma assisted molecular beam epitaxy. We study the effect of substrate treatments (i.e., O-plasma and Ga-etching) and several deposition parameters (i.e., growth temperature and metal-to-oxygen flux ratio) on the resulting Ga2O3 surface morphology and growth rate. In situ and ex-situ characterizations identified the formation of (110) and (ˉ110)-facets on the nominally oriented (010) surface induced by the Ga-etching of the substrate and by several growth conditions, suggesting (110) to be a stable (yet unexplored) substrate orientation. Moreover, we demonstrate how metal-exchange catalysis enabled by an additional In-flux significantly increases the growth rate (>threefold increment) of monoclinic Ga2O3 at high growth temperatures, while maintaining a low surface roughness (rms < 0.5 nm) and preventing the incorporation of In into the deposited layer. This study gives important indications for obtaining device-quality thin films and opens up the possibility to enhance the growth rate in β-Ga2O3 homoepitaxy on different surfaces [e.g., (100) and (001)] via molecular beam epitaxy.
关键词： molecular beam epitaxy,metal-exchange catalysis,surface morphology,homoepitaxy,β-Ga2O3
更新于2025-09-04 15:30:14
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Influence of Light Emitting Diode on Bone Marrow and Healing of Dermatome Wounds
摘要： The irradiation of large surfaces or whole body with light emitting diode LED λ-470 nm and λ-940 nm (LED shower) causes structural changes in bone marrow and stimulates healing of experimental dermatome wounds. The increase of migration of the bone marrow cells in derma and epithelial layers of skin indicates that LED-shower intensifies intercellular interactions and cells migration between tissues.
关键词： Bone marrow,Dermatome wounds,Light emitting diode irradiation,Morphology
更新于2025-09-04 15:30:14