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[Lecture Notes in Mechanical Engineering] Advances in Thin Films, Nanostructured Materials, and Coatings (Selected Papers from the 2018 International Conference on “Nanomaterials: Applications & Properties”) || Stain Effect on the Properties of Polar Dielectric Thin Films
摘要： Low cost scalable processing and substrates are critical for optimized polar dielectric performance of functional oxide thin ?lms if they are to achieve commercialization. Here, we present a comprehensive investigation of the role low-cost MgO, Al2O3, SrTiO3 and Si substrates on the structural and electrical properties of sol-gel derived SrTiO3 (ST) and K0.5Na0.5NbO3 (KNN) thin ?lms. The substrate is found to have a strong effect on the stress/stain state and, consequently, on the dielectric and ferroelectric response of the ?lms. A tensile stress induced in-plane by the thermal expansion mismatch between the substrates and the ?lms observed for ST and KNN ?lms deposited on platinized Al2O3 and Si substrates, respectively, lowers the relative permittivity and remanent polarization values in the parallel plate capacitor geometry. In contrast, a compressive stress/strain observed for ST ?lms deposited on MgO/Pt and KNN ?lms on SrTiO3/Pt substrates result in superior polarization and dielectric permittivity, corresponding to enhanced out-of-plane displacement of Ti4+ ions in ST ?lms and Nb5+ ions in KNN ?lms. It is thus demonstrated that for polycrystalline polar dielectric thin ?lms the relative permittivity and polarization may be optimized through an induced compressive stress state.
关键词： Dielectric properties,Sol-gel,Thin ?lms,Stress/strain,Thermal expansion,Ferroelectric hysteresis
更新于2025-11-14 17:28:48
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Optical, charge transport and magnetic properties of palladium retrieved from photometric measurements: approaching the quantum mechanics background
摘要： A parametric Drude–Lorentz (DL) model is used to describe the spectral variation of the dielectric functions of bulk palladium samples at low and room temperature. In addition to the contribution of conduction electrons, the contribution of holes is also explicitly accounted for in the model. A simulated annealing method is applied to obtain the optimized values of the parameters involved in the model: volume plasma frequency of conduction electrons, high frequency dielectric constant, collision frequency of holes and corresponding relaxation time, and two additional parameters from which the effective mass of holes and collision frequency of conduction electrons are evaluated. Oscillatior strengths, resonance frequencies, and widths entering in the Lorentz contribution to the dielectric function are also optimized. Renormalization of the oscillator strengths requires the introduction of a new parameter in the context of the DL model: the ratio between number density of conduction electrons and number density of metal atoms, whose optimized value ?ts very well with its evaluation from band structure calculations and from independent measurements. Inclusion of this parameter in the framework allows us to evaluate additional quantities related to the charge-carrier transport: average effective masses, Fermi energies and electronic densities of states at the corresponding Fermi energies, intrinsic electrical resistivity, intrinsic mean free paths, heat capacities, mobilities, as well as paramagnetic and diamagnetic susceptibilities, for both electrons and holes. The optimized resonance frequencies are compared with energy differences between plausible interband transitions, in accordance with reported band structure diagrams and with our own band structure obtained from density functional theory calculations.
关键词： Drude–Lorentz model,palladium,density functional theory,simulated annealing,metal thin ?lms
更新于2025-11-14 15:19:41
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Combustion synthesis of nontoxic water-induced InYO thin film and application in thin film transistor
摘要： In the work, novel indium yttrium oxide (InYO) thin ?lms are prepared by an environmentally friendly aqueous solution process. Y element is added to suppress the generation of oxygen vacancies. The e?ect of Y doping on the performance and stability of nontoxic water-induced InYO thin ?lm transistors (TFTs) is ?rstly examined. With the increase of Y doping contents, o?-state current is decreased and mobility decreases from 15.8 to 11.7 cm2 V?1 s?1. Furthermore, the stability under positive bias stress is also obviously improved. The device with 2 mol% Y element shows an optimized electrical performance and good stability, including mobility of 12.8 cm2/V s, threshold voltage of 1.4 V, subthreshold swing of 0.33 V/decade and threshold voltage shift of 2.31 V under positive voltage stress of 5 V for 10,000 s. The performance improvement is attributed to the decrease of oxygen vacancies and the decline of interface trap density by Y addition.
关键词： Thin ?lms,Amorphous materials,Electrical properties,Sol-gel chemistry
更新于2025-09-23 15:23:52
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Optical and electrical properties of thermally evaporated Se90Sb10 thin film
摘要： Chalcogenide Se90Sb10 thin ?lms are deposited by thermal evaporation from the bulk alloy. X-ray di?raction examination for the annealed ?lms shows the amorphous-crystalline transformation. This is bene?cial for optical disk data storage technology. The crystallinity is improved by increasing the annealing temperature. The ?lms annealed at relatively low temperatures exhibit highly transparence reaching to about 90% at incident light of wavelength of 900 nm. The as-prepared and annealed Se90Sb10 ?lms reveal an indirect allowed optical transition. The annealed ?lm at 473 K has an optical band gap of 1.676 eV which is suitable value for solar cell as photovoltaic application. Both the indirect optical energy band gap (Eg) and the oscillator energy (Eo) decrease whereas the oscillator strength (Ed) increases with increasing the annealing temperature. The annealing increases the conductivity and decreases the activation energy for conduction resulting in enhancement of ?lm properties for adapting to solar cells.
关键词： Electrical conductivity,Chalcogenide,Optical constants,Thin ?lms
更新于2025-09-23 15:21:21
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Chemical bath deposition of SnS:In thin films for Pt/CdS/SnS:In/Mo photocathode
摘要： SnS:In thin ?lms have been deposited on Mo substrates by chemical bath deposition method in acidic solution. The in?uences of di?erent In-doped concentrations on the morphological, structural, optical properties and phase purities of SnS thin ?lms have been investigated. Many sheet-like particles exist in the deposited SnS:In thin ?lms. The doping of indium will decrease the thicknesses of the deposited thin ?lms. The studies of photo-electrochemical (PEC) properties of SnS:In (In,10 at.%) thin ?lms indicate that their PEC properties are enhanced by the annealing process. The fabrication of Pt/CdS/annealed SnS:In/Mo photocathode can further enhance the photo-current density to 0.790 mA·cm?2 at ?0.4 V.
关键词： Thin ?lms,Chemical bath deposition,SnS,Photocurrent
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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Morphology study and threshold measurement of laser induced damage of nano-porous antireflective silica thin films in nano- and femtosecond pulse regimes
摘要： Laser induced damage threshold (LIDT) of nano-porous antire?ective silica thin ?lms is measured using 10 ns laser pulses at k = 532 nm. The thin ?lms are prepared by dip-coating of BK7 substrates and then drying them by three different heating methods, to see how their LIDT and transmission are affected. Furthermore, using SEM imaging, the morphology of the laser induced damages is inspected and compared to those of similar samples, previously irradiated by femtosecond laser pulses at k = 800 nm. The images evidently show that in the regions damaged by nanosecond pulses, the silica nanoparticles are melted and fused to each other, while in the samples irradiated by femtosecond pulses, the silica nanoparticles are sputtered and dispersed around, in the damaged area. The SEM images clearly demonstrate the different damage mechanisms involved in the nanosecond and femtosecond regimes of interaction.
关键词： Optical thin ?lms,Silica thin ?lms,Nano-porous thin ?lms,Laser damage
更新于2025-09-23 15:21:01
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Ultra-wide-bandgap (ScGa)2O3 alloy thin films and related sensitive and fast responding solar-blind photodetectors
摘要： Although b-Ga2O3 is considered an excellent candidate for solar-blind photodetectors (PDs) owing to its direct bandgap (4.9 eV) and high stability, the cut-off wavelength often oversteps the DUV region, reducing the rejection ratio of the PD. Moreover, oxygen vacancies, which always appear in b-Ga2O3 ?lms, act as trap centers hindering carrier recombination and signi?cantly lowering response speed. To disentangle these issues, we propose in this work to modify b-Ga2O3 by incorporating Sc to form ternary (ScGa)2O3 alloys. Thanks to the wider bandgap of Sc2O3 (~5.7 eV) than Ga2O3 and stronger SceO bonding than GaeO, the (ScGa)2O3 alloy ?lms exhibit a wider bandgap (5.17 eV) with fewer oxygen vacancies compared with pure-Ga2O3, as expected, which eventually lead to an ultra-low dark current (0.08 pA at 10 V) and faster response times (trise: 41/149 ms; tdecay: 22/153 ms) of the alloy ?lm-based PDs. Furthermore, the peak and cut-off response wavelengths of the (ScGa)2O3 PD are blue shifted relative to the pure Ga2O3 PD, resulting in a higher rejection ratio (>500 vs ~317). The Sc-alloying strategy, taking advantage of wider bandgap of Sc2O3 and stronger SceO bonding to widen the bandgap while reducing the intrinsic carriers and oxygen vacancies in the (ScGa)2O3 alloy, is expected to be generally applicable to the design of other wide-bandgap oxide alloys for developing high-performance UV photodetectors with a low dark current and high response speed.
关键词： Ga2O3 thin ?lms,Pulsed laser deposition,Solar-blind photodetectors,Sc-alloying
更新于2025-09-23 15:21:01
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Effect of Grain Size on the Fracture Behavior of Organic-Inorganic Halide Perovskite Thin Films for Solar Cells
摘要： Organic-inorganic halide perovskite (OIHP) thin ?lms at the heart of the new perovskite solar cells (PSCs) are very brittle, limiting the mechanical reliability of PSCs. Here we show that ?ne-grained MAPbI 3 (prototypical OIHP) ?lms with grain size (~290 nm) smaller than the typical ?lm thickness (~500 nm) tend to fracture intergranularly, resulting in low toughness (0.41 J.m ?2 ). In contrast, MAPbI 3 /substrate interfacial fracture occurs in ?lms with grains larger (~730 nm) than the ?lm thickness, resulting in much higher toughness (1.14 J.m ?2 ). Thus, coarse-grained OIHP ?lms are deemed desirable for not only improved PSCs performance and stability but also mechanical reliability.
关键词： Thin ?lms,Solar cells,Halide perovskites,Mechanical behavior,Grain boundaries
更新于2025-09-23 15:21:01
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Influence of Film Morphology on Transient Photocurrent Pulse Shape in Organic Thin Films: A Monte Carlo Study
摘要： The in?uence of ?lm morphology on the broadening of the time-of-?ight transient photo-current pulse is investigated using Monte Carlo simulation. Simulation of the time-of-?ight transient photo-current pulse shape is carried out for homogeneous and inhomogeneous organic thin ?lms by varying the overall energetic disorder. In homogeneous system, the value of the tail broadening parameter (W) of the photocurrent pulse is found to decrease upon decreasing the energetic disorder, which can be attributed to the variation in the non-thermal ?eld assisted diffusion. Interestingly, in the case of inhomogeneous system, upon decreasing the overall energetic disorder of the system the value of W initially attains a maximum value before it starts decreasing. This observation is explained in terms of the morphology dependent carrier diffusion. This study asserts the importance of the in?uence of the morphology dependent carrier diffusion on the charge transport in disordered systems and the related experimental measurements.
关键词： Polycrystalline organic thin ?lms,Charge transport,Tail broadening,Diffusion,Time of ?ight photoconductivity,Film Morphology
更新于2025-09-23 15:21:01