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Study on structural, optical and hydrophilic properties of FTO/TiO2 tandem thin film prepared by aerosol-assisted chemical vapor deposition method
摘要： Homogeneous TiO2 thin films were prepared on fluorine-doped tin oxide (SnO2:F, FTO) substrate using aerosol-assisted chemical vapor deposition with nano-TiO2 suspension as precursors. The effects of annealing temperature on the structural, optical, electrical and hydrophilic properties have been investigated in detail. The results revealed that the nano-TiO2 precursors with averages particle size of 5 nm to 7 nm formed a uniform and smooth surface morphology on FTO substrates after annealing process. By controlling annealing temperature, the FTO/TiO2 tandem films simultaneously exhibited excellent emissivity and water contact angle with values of about 0.13 and 5°, respectively. The enhancement of the hydrophilicity was attributed to the emerging heterojunction at the FTO/TiO2 interface. The FTO/TiO2 tandem films prepared here have favorable prospective applications in the field of energy-saving coated glass for their hydrophilicity and low-emissivity performance.
关键词： Low-emissivity,Hydrophilic properties,Tandem films,Energy-saving coated glass
更新于2025-09-04 15:30:14
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Synthesis and electrochromic properties of molybdenum oxide films
摘要： Molybdenum oxide (MoOx) thin films were prepared by pulse DC sputtering using a molybdenum target and their optical and electrochromic properties were investigated. These MoOx thin films were reactively sputter-deposited at various oxygen flow rates. The effects of the oxygen flow rate on the growth and microstructure of the molybdenum oxide films were examined using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The optical density and modulation of the MoOx films were analyzed using a UV/VIS spectrophotometer (UV-visible). Electrochromic tests were conducted using an electrochemical analyzer. Experimental results reveal that the electrochromic properties depended strongly on the crystalline phase, thickness, chemical composition and microstructure, which were controlled by varying the oxygen flow rate.
关键词： Pulse DC sputtering,Oxygen flow rates,Electrochromic tests,MoOx thin films
更新于2025-09-04 15:30:14
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Growth and surface structural study of tin oxide films on Ag(001)
摘要： Tin oxide was prepared by reactive deposition of Sn in an O2 atmosphere at both room temperature (RT) and high temperature (HT) at 573 K as well from one monolayer to ten monolayer film coverages. The grown films were studied at RT by a combination of x-ray photoemission spectroscopy (XPS), low energy electron diffraction (LEED) and ultraviolet photoemission spectroscopy (UPS). At RT, the coexistence of both SnO and SnO2 was confirmed by XPS and valence band data with more SnO being formed at higher coverage. However, only one oxidised phase of tin oxide mainly due to SnO2 was formed at HT for most of the coverage. Presence of SnO was also confirmed only at the highest coverage studied here for HT. A multidomain LEED pattern having square (1 × 1) domains at 30° to each other was reported for low coverage of tin oxide at RT, which with an increase in coverage, gives rise to diffused background confirming no ordered tin oxide was formed. The similar multi-domain structure was also noticed for HT growth from lower coverage up to 5 monolayer equivalent (MLE) coverage which then transformed into hexagonal multidomain LEED pattern for higher coverage confirming the presence of clear oxide phase, unlike the RT growth case.
关键词： Thin films,Low energy electron diffraction,Photoemission spectroscopy
更新于2025-09-04 15:30:14
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Ultrasonic Studies of Solid Azobenzene-Decorated Polymer Thin Films
摘要： This work investigates the effect of ultrasound on switching of cis azobenzene isomers to their trans counterparts in solid films of methyl methacrylate and methacryloyloxyazobenzene copolymers [P(MMA/MOAB)]. Ultraviolet?visible and 1H nuclear magnetic resonance spectroscopies demonstrate that 46% of the cis isomer converts to the trans form purely by ultrasonic agitation and 46% converts to the trans isomer by localized ultrasound-induced heating effects. Comparative studies of isomerization by ultrasound wave, heat, and visible irradiation show that ultrasound exposure requires a longer time to switch the cis-to-trans conformation. The estimated activation energy for the cis-to-trans conversion in solid polymer films is shown to be comparable to previous values of azobenzene isomerization, indicating that incorporation of the chromophore in a polymeric system affects the kinetics of transition but not the barriers to conformational change.
关键词： azobenzene,nuclear magnetic resonance spectroscopy,polymer thin films,ultrasound,isomerization,ultraviolet?visible spectroscopy
更新于2025-09-04 15:30:14
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Real-time switching dynamics of ferroelectric tunnel junctions under single-shot voltage pulses
摘要： In ferroelectric memory devices, information is stored within the polarization direction whose reversal usually occurs by the nucleation and propagation of domains. In ultrathin ferroelectrics, ultrafast dynamics may be achieved by nucleation-limited switching, avoiding the inherently speed-limited propagation of domain walls. Here, we investigate polarization reversal dynamics in ultrathin ferroelectric films by transient current measurements. Thanks to the tunnel electroresistance, the start of polarization reversal induces sharp variations of the transmitted current under voltage pulses. These single-shot measurements show extremely fast switching with durations down to 3 ns that is only limited by the current device geometry. While the OFF-to-ON switching shows finite nucleation times that scale with the pulse amplitude, the ON-to-OFF switching speed cannot be detected under such rectangular pulses. Resorting to triangular pulse excitations allows us to detect the dynamics of this switching direction. Both cases can be interpreted by nucleation switching models following Merz’s law.
关键词： transient current measurements,nucleation-limited switching,single-shot measurements,Merz’s law,ferroelectric memory devices,ultrathin ferroelectric films,polarization reversal dynamics,tunnel electroresistance
更新于2025-09-04 15:30:14
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Effect of microstructural changes in the biological behavior of magnetron sputtered ZnO thin films
摘要： This work is focused on the evaluation of the correlation between the microstructural changes of zinc oxide (ZnO) thin films and its biological behavior. For this study, ZnO thin films were prepared by reactive magnetron sputtering, using different deposition times and reactive gas (O2) flows, and tested against a fungal pathogenic species, Candida albicans. Results showed that the increase of thickness of the films did not affect significantly the surface roughness but changed the crystalline structure of the films (ZnO in the hcp structure), which was followed by a small increase of antifungal properties, leading to a decrease of viable cells. The decrease of O2 flow in the deposition chamber affected the roughness only slightly (roughly 1 nm difference between the different films) but resulted in a clear decrease in the crystallinity of thin films, which improved even further their antifungal activity. These results seem to indicate a correlation between structural features and the antifungal behavior of the ZnO thin films, which will be shown by different analyses. When tested against the fungal species, the films showed to be capable of reducing the growth rate and inhibit their growth, leading to a low number of microbial cells at the end of the experiment. A deeper analysis by flow cytometry on how the thin films affected the microbial cells showed a reduced global enzymatic activity in yeast cells after contact with the materials’ surface.
关键词： antifungal properties,magnetron sputtering,ZnO thin films,microstructural changes,biological behavior
更新于2025-09-04 15:30:14
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Deposition and Patterning of Polycrystalline Diamond Films Using Traditional Photolithography and Reactive Ion Etching
摘要： Given the exceptional characteristics of diamond films, they have become increasingly popular in the fields of medicine, microelectronics, and detector electronics. However, despite all the advantages, there are many technological problems that complicate their widespread application and impose limitations on diamond use in technological processes. In this study, we proposed a new technique for obtaining a complex topology of polycrystalline diamond coatings by selective seeding of the substrate by nucleation centers and subsequent surface treatment with reactive ion etching to reduce the number of parasitic particles. As a result, diamond films were obtained with a high particle concentration in the film region and high repeatability of the pattern. Moreover, parasitic particles influenced neutralization in areas where film coverage was not needed. The effect of the diamond nanoparticle concentration in a photoresist and the effect of reactive ion etching on the formation of a continuous film and the removal of parasitic nucleation centers were examined. The relative simplicity, low power consumption, and high efficiency of this method make it attractive for both industrial and scientific applications.
关键词： pattern,diamond,parasitic particles,deposition,photolithography,reactive ion etching,films,selective,CVD
更新于2025-09-04 15:30:14
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Strain-Mediated Substrate Effect on the Dielectric and Ferroelectric Response of Potassium Sodium Niobate Thin Films
摘要： If piezoelectric thin films sensors based on K0.5Na0.5NbO3 (KNN) are to achieve commercialization, it is critical to optimize the film performance using low-cost scalable processing and substrates. Here, sol–gel derived KNN thin films are deposited using a solution with 5% of potassium excess on Pt/TiO2/SiO2/Si and Pt/SrTiO3 substrates, and rapid thermal annealed at 750 ?C for 5 min. Despite an identical film morphology and thickness of ~335 nm, an in-plane stress/strain state is found to be tensile for KNN films on Pt/TiO2/SiO2/Si, and compressive for those on Pt/SrTiO3 substrates, being related to thermal expansion mismatch between the substrate and the film. Correspondingly, KNN films under in-plane compressive stress possess superior dielectric permittivity and polarization in the parallel-plate-capacitor geometry.
关键词： stress/strain,ferroelectric hysteresis,dielectric properties,KNN thin films,sol–gel,thermal expansion
更新于2025-09-04 15:30:14
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High Performance On-Chip Supercapacitors Based on Mesoporous Silicon Coated with Ultrathin Atomic-Layer-Deposited In2O3 Films
摘要： On-chip supercapacitors have attracted considerable attention due to their high power density, long cycling life and compatibility with integrated circuits. One critical drawback that restricts their practical application is the low energy density. In this work, low-resistivity mesoporous silicon with a high aspect ratio is prepared by Pt film assisted-chemical etching and utilized as the scaffold of the supercapacitors. Subsequently, low resistivity (0.001 Ω·cm) and ultrathin In2O3 films are coated on the mesoporous silicon scaffold by atomic layer deposition at 200 oC, serving as the active electrode material. The electrochemical measurements reveal that the coating of the In2O3 film remarkably improves the performance of the supercapacitors compared to those without the In2O3 coating. The supercapacitors with a 4.5 nm In2O3 film coating exhibit a capacitance density of 1.36 mF/cm2 at a scan rate of 10 mV/s as well as a better stability against the scan rate. In addition, it is found that the pristine mesoporous silicon walls are collapsed after 400 times of sweeping while those with the In2O3 film coating are still intact even after 2000 times of sweeping. Meanwhile, a high energy density is also achieved without sacrificing the power performance.
关键词： In2O3 films,Pt assisted chemical etching,Mesoporous silicon,On-chip supercapacitors,Atomic layer deposition
更新于2025-09-04 15:30:14
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Electrodeposition of catalytically active polyporphyrin films of metal complexes of amino-substituted tetraphenylporphyrins
摘要： The process of electrodeposition of polyporphyrin films based on amino-substituted tetraphenylporphyrins and their metal complexes (CuT(p-NH2Ph)P, FeClT(m-NH2Ph)P, MnClT(m-NH2Ph)P) has been studied by the quartz crystal microbalance method. The surfaces of the films have been characterized by the scanning electron microscopy method and the number of electrons taking part in porphyrin electropolymerization has been determined. It has been established that the most intensive film growth is observed for the metal-free porphyrin ligand. The obtained polyporphyrin films have been analyzed for the catalytic ability in oxygen electroreduction reactions.
关键词： electropolymerization,polyporphyrin films,quartz crystal microbalance method,oxygen electroreduction.
更新于2025-09-04 15:30:14