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The physical characteristics of epitaxially sputtered La0.67Ca0.33MnO3 (LCMO) films are modified by twinning when deposited on different single crystal substrates at varying thicknesses. Comprehensive high-resolution x-ray diffraction measurements reveal the formation of two types of tilted domains, whose influence becomes prominent in rocking curve scans with increasing thickness. The occurrence of twinning is attributed to the shear strain relaxation process that accommodates the lattice symmetry mismatch between the film and the substrate. In the electrical transport properties of thicker films, the effect of twinning manifests as a broadening of the insulator–metal transition in resistance–temperature (R–T) plots, in which an extra hump emerges. This broadening effect is also noticeable in magnetoresistance curves, leading to a large magnetoresistance spread over a broad temperature range. While the additional hump in R–T plots vanishes under stronger magnetic fields, the persistent broadening of the transition and magnetoresistance suggests that twinning continues to influence the film properties even at higher field strengths. Thick LCMO films exhibit similar broadening in the transition from the paramagnetic to ferromagnetic phase with an additional transition during magnetic (M–T) measurements. In contrast, LCMO films of lesser thickness display sharp electrical and magnetic transitions without significant evidence of any supplementary transition. These results suggest that the twinning effect in films, caused by substrate-induced strain relaxation, can profoundly alter the transport properties of these functional films and substantially widen the temperature range where maximum magnetoresistance is observed. [ABSTRACT FROM AUTHOR]

This study focuses on establishing and validating a method to accurately measure the in-plane thermal conductivity of very conductive thin films, such as single-crystal metals or semiconductors, 2D and nanostructured materials. By integrating both 2 ω and 3 ω measurements, the method is rendered insensitive to the superficial thermal boundary resistance of the insulating overlayer, enabling precise estimation of the in-plane thermal properties of conductive films grown on top of substrates or multilayer stacks. The proposed technique is applied to analyze the thermal conductivity of a silicon-on-insulator stack with a top layer consisting of a 340 nm thick film of monocrystalline silicon. Measurements are conducted within a temperature range spanning from 250 to 325 K. The results confirm the method's capability to correctly assess the thermal conductivity decrease of the silicon film compared to bulk value, demonstrating its reliability for the thermal characterization of conductive thin films. [ABSTRACT FROM AUTHOR]

The peculiar superconducting properties of granular aluminum, which consists of nanometer-sized aluminum grains separated by aluminum oxide, are attractive for applications in quantum circuitry, and they are interesting from a fundamental materials physics view. The phase diagram of granular aluminum as a function of normal-state resistivity features a superconducting dome with a maximum critical temperature T c well above the T c = 1.2 K of pure aluminum. Here, we show how the maximum T c of this superconducting dome grows if the substrate temperature during deposition is lowered from 300 K to cooling with liquid nitrogen (150 and 100 K) and liquid helium (25 K). The highest T c that we observe is 3.27 K. These results highlight that granular aluminum is a model system for complex phase diagrams of superconductors and demonstrate its potential in the context of high kinetic inductance applications. This is augmented by our observation of comparably sharp superconducting transitions of high-resistivity samples grown at cryogenic temperatures and by a thickness dependence even for films substantially thicker than the grain size. [ABSTRACT FROM AUTHOR]

GaN grown via oxide vapor phase epitaxy (OVPE-GaN) can produce free-standing substrates with ultra-low resistivity because of the high doping concentration of oxygen. The bulk growth of OVPE-GaN is hindered by polycrystals generated during long-term growth. We have previously reported that thicker films can be grown by reducing the partial pressure of water vapor in the growth atmosphere with CH4. However, as CH4 is a dopant of carbon, a compensating acceptor, its addition may increase electrical resistance. In this study, we further investigated the effect of reducing water vapor partial pressure on polycrystals by combining Ga2O production (reaction of Ga and water vapor: a Ga–H2O system), which can reduce water vapor, with CH4 addition. However, CH4 addition to the Ga–H2O system increased polycrystal generation, possibly owing to the thermal decomposition of excess CH4. The properties of OVPE-GaN with CH4 addition were also evaluated. Although the CH4 addition resulted in high carbon doping, the carbon-doped OVPE-GaN maintained low resistivity. This is because the OVPE method involves three-dimensional growth with growth pits, and the growth pits leave behind low-resistivity high-oxygen-concentration regions. As the resistivity remains low even when CH4 is added in the OVPE method, both polycrystallization suppression and low resistivity can be achieved by selecting an appropriate CH4 flow rate. [ABSTRACT FROM AUTHOR]

It is crucial to better understand the magnetization reversal process between soft and hard magnets and to achieve a high maximum energy product in thick composite multilayers. In this study, we find that the exchange interactions dominate in soft–hard-magnetic composite bilayers, while dipole interactions are predominant in soft–hard-magnetic composite trilayers. Based on the first-order reversal curve, magnetization reversal models are developed for both the thick composite bilayer and trilayer. Dipole interactions play an important role in the long range, resulting in higher coercivity and remanence in the thick trilayer. A multilayer in a stacked trilayer structure is achieved, which is composed of thick films with a perpendicular magnetic anisotropy at a thickness of up to 16 μm. The enhanced dipole interactions lead to a remanent polarization of 1 T and a maximum energy product of 22.5 MGOe. This work contributes to the preparation of thick films with a high maximum energy product for applications in magnetic microelectromechanical systems. [ABSTRACT FROM AUTHOR]

Scanning spreading resistance microscopy (SSRM) measurements were performed on GaAs thick films grown by hydride vapor phase epitaxy technology under different growth conditions to evaluate their carrier concentrations. For this purpose, a calibration curve was established based on a multilayer staircase structure grown by molecular beam epitaxy. The dopant calibration range measured by secondary ion mass spectrometry is from 5 × 1016 to 1019 cm−3. An abnormal phenomenon in the calibration process was explained by taking into account the parasitic parallel resistance of the calibration samples. Finally, the calibration curve was used to quantitatively analyze the carriers inside the Zn doping p-type GaAs film from 4 × 1016 to 1018 cm−3 range. We demonstrate here the applicability of SSRM to the in-depth analysis of thick epilayers, providing new inputs for the control of thick film technologies. [ABSTRACT FROM AUTHOR]

In this work, we present the investigation of the magnetotransport properties of a capped SnTe film, grown by molecular beam epitaxy, using Shubnikov–de Haas oscillations for the detection of Dirac fermions. The cap layer used was a 10 nm thick Sn0.98Eu0.02Te film, which can also contribute to the transport such that it is mandatory to isolate its contribution from the electrical transport measured in the sample. To separate the contribution from both layers, photoconductivity measurements were performed. A detailed analysis of the Shubnikov–de Haas oscillations is carried out using theoretical expressions and building the Landau-level indexation. We found that Dirac fermions are detected in the SnTe layer, while the cap layer contributes with trivial fermions, protecting SnTe against deterioration due to exposure to the atmosphere. [ABSTRACT FROM AUTHOR]

Achieving the formation of target open crystalline lattices from colloidal particles is of paramount importance for their potential application in photonics. Examples of such desired structures are the diamond, tetrastack, and pyrochlore lattices. Here, we demonstrate that the self-assembly of tetravalent patchy particles results in the selective formation of cubic tetrastack crystals, both in the bulk and in the systems subjected to external fields exerted by the solid substrate. It is demonstrated that the presence of an external field allows for the formation of well-defined single crystals with a low density of defects. Moreover, depending on the strength of the applied external field, the mechanism of epitaxial growth changes. For weakly attractive external fields, the crystallization occurs in a similar manner as in the bulk, since the fluid does not wet the substrate. Nonetheless, the formed crystal is considerably better ordered than the crystals formed in bulk, since the surface induces the ordering in the first layer. On the other hand, it is demonstrated that the formation of well-ordered cubic tetrastack crystals is considerably enhanced by the increase in external field strength, and the formation of the thick crystalline film occurs via a series of layering transitions. [ABSTRACT FROM AUTHOR]

Growth of GeSn films directly on Si substrates is desirable for integrated photonics applications since the absence of an intervening buffer layer simplifies device fabrication. Here, we analyze the microstructure of two GeSn films grown directly on (001) Si by remote plasma-enhanced chemical vapor deposition (RPECVD): a 1000 nm thick film containing 3% Sn and a 600 nm thick, 10% Sn film. Both samples consist of an epitaxial layer with nano twins below a composite layer containing nanocrystalline and amorphous. The epilayer has uniform composition, while the nanocrystalline material has higher levels of Sn than the surrounding amorphous matrix. These two layers are separated by an interface with a distinct, hilly morphology. The transition between the two layers is facilitated by formation of densely populated (111)-coupled nano twins. The 10% Sn sample exhibits a significantly thinner epilayer than the one with 3% Sn. The in-plane lattice mismatch between GeSn and Si induces a quasi-periodic misfit dislocation network along the interface. Film growth initiates at the interface through formation of an atomic-scale interlayer with reduced Sn content, followed by the higher Sn content epitaxial layer. A corrugated surface containing a high density of twins with elevated levels of Sn at the peaks begins forming at a critical thickness. Subsequent epitaxial breakdown at the peaks produces a composite containing high levels of Sn nanocrystalline embedded in lower level of Sn amorphous. The observed microstructure and film evolution provide valuable insight into the growth mechanism that can be used to tune the RPECVD process for improved film quality. [ABSTRACT FROM AUTHOR]

Quantum memories facilitate the storage and retrieval of quantum information for on-chip and long-distance quantum communications. Thus, they play a critical role in quantum information processing and have diverse applications ranging from aerospace to medical imaging fields. Bulk acoustic wave (BAW) phonons are attractive candidates for quantum memories because of their long lifetimes and high operating frequencies. In this study, we establish a modeling approach to design hybrid magnonic high-overtone bulk acoustic wave resonator (HBAR) structures for high-density, long-lasting quantum memories, and efficient quantum transduction devices. We illustrate the approach by investigating a hybrid magnonic system, consisting of a gadolinium iron garnet (GGG) thick film and a patterned yttrium iron garnet (YIG) thin film. The BAW phonons are excited in GGG thick film via coupling with magnons in the YIG thin film. We present theoretical and numerical analyses of the diffraction-limited BAW phonon lifetimes, modeshapes, and magnon–phonon coupling strengths in YIG/GGG planar and confocal HBAR (CHBAR) structures. We utilize Fourier beam propagation and Hankel transform eigenvalue problem methods and compare the two methods. We discuss strategies to improve the phonon lifetimes in the diffraction-limited regime, since increased lifetimes have direct implications on the storage times of quantum states for quantum memory applications. We find that ultra-high cooperativities and phonon lifetimes on the order of ∼ 10 5 and ∼ 10 milliseconds, respectively, could be achieved using a CHBAR structure with 10 μ m YIG lateral area. Additionally, high integration density of on-chip memory or transduction centers is naturally desired for high-density memory or transduction devices. The proposed CHBAR structure will offer more than 100-fold improvement of integration density relative to a recently demonstrated YIG/GGG device. Our results will have direct applicability for devices operating in the cryogenic or milliKelvin regimes. For example, our study will inform the design of HBAR devices that could couple with superconducting qubits for promising quantum information platforms. [ABSTRACT FROM AUTHOR]

We extend the force-level elastically collective nonlinear Langevin equation theory to treat the spatial gradients of the alpha relaxation time and glass transition temperature, and the corresponding film-averaged quantities, to the geometrically asymmetric case of finite thickness supported films with variable fluid–substrate coupling. The latter typically nonuniversally slows down motion near the solid–liquid interface as modeled via modification of the surface dynamic free energy caging constraints that are spatially transferred into the film and which compete with the accelerated relaxation gradient induced by the vapor interface. Quantitative applications to the foundational hard sphere fluid and a polymer melt are presented. The strength of the effective fluid–substrate coupling has very large consequences for the dynamical gradients and film-averaged quantities in a film thickness and thermodynamic state dependent manner. The interference of the dynamical gradients of opposite nature emanating from the vapor and solid interfaces is determined, including the conditions for the disappearance of a bulk-like region in the film center. The relative importance of surface-induced modification of local caging vs the generic truncation of the long range collective elastic component of the activation barrier is studied. The conditions for the accuracy and failure of a simple superposition approximation for dynamical gradients in thin films are also determined. The emergence of near substrate dead layers, large gradient effects on film-averaged response functions, and a weak non-monotonic evolution of dynamic gradients in thick and cold films are briefly discussed. The connection of our theoretical results to simulations and experiments is briefly discussed, as is the extension to treat more complex glass-forming systems under nanoconfinement. [ABSTRACT FROM AUTHOR]

Magnetic garnet thin films exhibiting perpendicular magnetic anisotropy (PMA) and ultra-low damping have recently been explored for applications in magnonics and spintronics. Here, we present a systematic study of PMA and magnetic damping in bismuth-substituted yttrium iron garnet (Bi-YIG) films grown on sGGG (111) substrates by pulsed laser deposition. Films with thicknesses ranging from 5 to 160 nm are investigated. Structural characterization using x-ray diffraction and reciprocal space mapping demonstrates the pseudomorphic growth of the films. The films exhibit perpendicular magnetic anisotropy up to 160 nm thickness, with the zero-magnetic field state changing from fully saturated for low thicknesses to a dense magnetic stripe pattern for thicker films. The films show a ferromagnetic resonance (FMR) linewidth of 100–200 MHz with a Gilbert damping constant of the order of 4 × 10 − 3 . The broad FMR linewidth is caused by inhomogeneities of magnetic properties on micrometer length scales. [ABSTRACT FROM AUTHOR]

Nb 3 Sn and V 3 Si thin films are promising candidates for the next generation of superconducting radio-frequency (SRF) cavities. However, sputtered films often suffer from stoichiometry and strain issues. This exploratory study investigates the structural and chemical effects of thermal annealing, both i n − s i t u and post-sputtering, on DC-sputtered Nb 3 Sn and V 3 Si films with varying thicknesses, deposited on Nb or Cu substrates. Building upon our initial studies [Howard et al., Proceedings of the SRF'21, East Lansing, MI (JACoW, 2021), p. 82.], we provide fundamental insights into recrystallization, phase changes, and the issues of stoichiometry and strain. Through annealing at 950 ° C, we have successfully enabled the recrystallization of 100 nm thin Nb 3 Sn films on Nb substrates, yielding stoichiometric and strain-free grains. For 2 μ m thick films, elevated annealing temperatures led to the removal of internal strain and a slight increase in grain size. Moreover, annealing enabled a phase transformation from an unstable to a stable structure in V 3 Si films, while we observed significant Sn loss in 2 μ m thick Nb 3 Sn films after high-temperature annealing. Similarly, annealing films atop Cu substrates resulted in notable Sn and Si loss due to the generation of Cu–Sn and Cu–Si phases, followed by evaporation. These results encourage us to refine our process to obtain high-quality sputtered films for SRF use. [ABSTRACT FROM AUTHOR]

The development of pulsed power technology demands high energy storage density dielectric materials. In this study, Sr0.7Bi0.2TiO3 relaxor ferroelectric (rFE) ceramic thick films were prepared using a tape-casting process. The ceramics exhibit a dense structure and typical rFE hysteresis curves, achieving an energy storage density of 4.77 J cm−3 and efficiency of 94.4%, attributed to the high polarization intensity, low remnant polarization, and low hysteresis loss of rFE. Additionally, the material demonstrates good temperature stability. Moreover, the Sr0.7Bi0.2TiO3 ceramic thick films show advantages in charge-discharge performance, capable of discharging within hundreds of nanoseconds and achieving a power density of 137 MW cm−3. Overall, the Sr0.7Bi0.2TiO3 ceramic thick film exhibits a comprehensive performance advantage in terms of energy storage density, efficiency, and power density. Additionally, the material was fabricated using the tape-casting process, which is compatible with subsequent multilayer ceramic capacitor production, indicating potential for further performance enhancement. [ABSTRACT FROM AUTHOR]

The role of pressure, temperature, and particle size on cold sintering of ZnO has been investigated with a view to developing transparent thick films for device applications. Coarse ZnO (∼90–250 nm, cZnO) particles exhibited equiaxed grain growth under all conditions eventually achieving grain sizes of ∼ 0.5–1.0 µm at 300°C/375 MPa. In contrast, nano‐ZnO (40–80 nm, nZnO), exhibited grain growth along the c‐axis with a broader grain size distribution (0.5–4 µm) at higher temperatures and pressure (300°C/375 MPa) than cZnO. The broader grain size distribution is attributed to greater dissolution for nZnO compared with cZnO coupled with redistribution of Zn acetate/acetic acid into pores. ZnO continues to dissolve and reprecipitate within the pores throughout the densification process resulting in localized, larger grain sizes. In plane grain growth normal to the pressing direction was observed at and near the sample surface particularly in nZnO, which is attributed to constrained‐sintering. Some abnormal grain growth (10–20 µm) was also sporadically observed near or at the surface of nZnO (300°C/375 MPa) due to greater rates of reprecipitation as the transient solvent volatilizes adjacent to the die wall/plunger. Tape casting was used to fabricate single and multiple layers (≈30 µm) of ZnO on Kapton® to demonstrate the potential for device fabrication. Transparency was achieved by choosing cold sintering conditions (200°C/250 MPa) for nZnO that gave ∼95% relative density while restricting a majority of grain growth to <200 nm so that internal light scattering from grain boundaries was avoided. [ABSTRACT FROM AUTHOR]

Nickel hydroxide (α-Ni(OH) 2) with large interlayer spacing is a promising pseudocapacitive material with high theoretical capacitance and good rate capability. However, the phase transition reversibility between α-Ni(OH) 2 and γ-NiOOH in alkaline electrolyte upon charging/discharging is still vague. In this study, the cycling reversibility of α-Ni(OH) 2 has been systematically investigated via adjusting the electrochemical deposition parameters. Structure characterizations and electrochemical analysis clearly revealed that the precursor concentration, deposition voltage and time significantly affect the mass loading of active material, the thicknesses of deposited films and their morphologies. Increasing the precursor concentration, deposition voltage and time lead to high mass loading, thick film and agglomerated nanosheets, which deteriorated the charge transfer and ion diffusion that lead to inferior cycling reversibility. In contrast, thin film with small mass loading and vertically-aligned nanosheets can be obtained upon deposition under low precursor concentration, small deposition voltage and short time, which shows facilitated charge transfer, ion diffusion and thereby high phase transition reversibility. Therefore, choosing appropriate deposition parameters would be beneficial to improve the electrode's cycling reversibility, which can effectively guide the development of more metal hydroxides with enhanced charge storage capability. [ABSTRACT FROM AUTHOR]

We investigate the growth of amorphous MoSi thin films using magnetron co-sputtering and optimize the growth conditions with respect to crystal structure and superconducting properties (e.g., critical temperature ). The deposition pressure, Mo:Si stoichiometry and substrate temperature are systematically varied to achieve a transition temperature of 8.4(3) K for films with a thickness of 17.7(8) nm and 6.2(9) K for a 4.3(4) nm thick film. For Mo concentrations above 81% the crystalline phase Mo 3 Si is observed in grazing incidence X-ray diffraction measurements. The same phase appears when the working pressure during deposition is reduced below 3. 1 × 10 -3 mbar and when the substrate temperature during deposition is increased above C. By choosing a sufficient Si concentration and optimum deposition pressure we identify deposition conditions that ensure a homogeneous amorphous growth of the superconducting thin film. We then fabricate superconducting nanowire single-photon detectors which exhibit an unitary internal efficiency to single photons at an operational temperature of 1.2 K while simultaneously having a dark count rate below 1 Hz. Our results establish the link between MoSi film deposition, morphology and the performance of SSPD. [ABSTRACT FROM AUTHOR]

The microstructure and corrosion behavior of the three regions, namely advancing side (AS), retreating side (RS), and center of the stir zone (CSZ) of friction stir welded UNS S32750 super duplex stainless steel (ferrite + austenite), were investigated. There is a significant grain refinement in these zones due to severe plastic deformation. Electrochemical corrosion behavior of the alloy was studied in freely exposed 0.5 M H2SO4 + 3.5 wt.% NaCl solution at room temperature. Perceptible difference in critical current and passivation current densities among the three zones and the base metal was noticed. These differences were mainly due to the variation in passive film thickness shown by these zones in the alloy. The studies show that the passive film thickness variation was due to significant differences in grain refinement seen and kernel average misorientation (KAM) in these zones of the alloy. It is postulated that the larger the grain boundary density and dislocation cells, the better is the ability of the alloy to form thick passive film. [ABSTRACT FROM AUTHOR]

We report on the fabrication and characterization of superconducting magnesium diboride (MgB2) thin films intended for quantum-limited devices based on non-linear kinetic inductance (NLKI) such as parametric amplifiers with either elevated operating temperatures or expanded frequency ranges. In order to characterize the MgB2 material properties, we have fabricated coplanar waveguide (CPW) transmission lines and microwave resonators using ≈ 40 nm thick MgB2 films with a measured kinetic inductance of ∼ 5.5 pH/ □ and internal quality factors Q i ≈ 3 × 10 4 at 4.2 K. We measure the NLKI in MgB2 by applying a DC bias to a 6 cm long by 4 μm wide CPW transmission line and measuring the resulting phase delay caused by the current dependent NLKI. We also measure the current dependent NLKI through CPW resonators that shift down in frequency with increased power applied through the CPW feedline. Using these measurements, we calculate the characteristic non-linear current parameter, I * , for multiple CPW geometries. We find values for corresponding current density, J * = 12 – 22 MA/cm2, and a ratio of the critical current to the non-linear current parameter, I C / I * = 0.14 – 0.26 , similar to or higher than values for other superconductors such as NbTiN and TiN. [ABSTRACT FROM AUTHOR]

We study the multi-photon energy resolution and demonstrate photon counting up to about 30 photons at near-infrared wavelengths in a kinetic inductance detector made from aluminum (Al) film. The detector has a lumped-element design comprising a large interdigitated capacitor in parallel with a narrow inductive strip. A fiber-coupled lens is used to focus the light onto the inductive absorber to minimize photon scattering. Detectors with different designs and film thicknesses are studied. From the histogram of the optimally filtered multi-photon response pulse height, we find that the square of the energy resolution of the n-photon peak Δ E n 2 increases linearly with the absorbed photon energy n h ν. The detector made from a thicker Al film has a smaller slope of Δ E n 2 with n h ν , suggesting lower phonon loss in a thicker absorber. We also discuss other factors that limit the energy resolution and maximum resolvable photon number, including the dark noise and position-dependent response. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN) is an ideal semiconductor material for the development of microelectronic and optoelectronic devices. Homo-epitaxial growth on high-quality GaN single crystal substrates is the fundamental way to achieve high performance of GaN-based devices. Hydride vapor phase epitaxy ( HVPE) is currently a most common approach for manufacturing the vast majority of commercially available GaN substrates. Owing to its high growth-rate, how to control the growth of HVPE-GaN with high growth-rate and high uniformity is of great significance for obtaining large-size high quality GaN substrates. Here, HVPE equipment for 6-inch GaN substrate is designed and developed independently. The effect of growth conditions such as the distance between source gas and substrate (D), separator gas, HCl and NH3 carrier gas flow-rates on the thickness-uniformity of as-grown GaN films have been studied with the help of numerical simulation and epitaxy experiments. Simulation and experimental results indicate that the self-developed HVPE system has the characteristics of high growth-rate and high thickness-uniformity. The introduction of separator gas and increasing D can effectively promote the diffusion of GaCl gas to the edge of substrates, so as to significantly improve the thickness-uniformity of the large size epitaxial thick films. By further optimizing the growth conditions, 6-inch GaN film with a thickness of ~ 11 μm achieved thicknessnonuniformity about ± 1. 5% and growth-rate more than 60 μm/ h. The growth-rate increases as the growth time increases. When the growth time is 3 h, the thickness of 6-inch GaN thick film is ~ 700 μm, the growth rate increases to > 200 μm/ h and the thickness-nonuniformity is still in the range of ± 5% . The corrosion effect of non-reactive HCl on the deposited GaN on the quartz tube wall may lead to the increase of GaCl concentration and thus increase the growth rate. The results will help us to design the large-size HVPE growth system and prepare large-area and high quality GaN substrates. [ABSTRACT FROM AUTHOR]

This study investigates the deposition and characterization of CaF₂ thin films with thicknesses ranging from 40 to 320 nm, fabricated via thermal evaporation onto glass substrates. X-ray diffractometry (XRD) revealed that increased film thickness leads to enhanced crystallinity, with larger crystallite sizes and reduced lattice strain. Wettability analysis demonstrated a transition from hydrophobic behavior (contact angle ∼70° for 40 nm) to hydrophilic behavior (contact angle ∼52° for 320 nm) as film thickness increased. Surface morphology, examined via atomic force microscopy (AFM), showed a significant reduction in surface roughness in thicker films, with smoother, more coalesced surfaces observed for films over 160 nm. Monofractal analysis further confirmed the evolution of surface microtexture, with thicker films exhibiting higher uniformity and reduced surface complexity. These findings provide critical insights into optimizing CaF₂ thin films for applications in optics, electronics, and surface coatings, where improved crystallinity and surface properties are essential. [ABSTRACT FROM AUTHOR]

Purpose: The study aims to develop an inexpensive metal oxide semiconductor gas sensor with high sensitivity, excellent selectivity for a specific gas and rapid response time. Design/methodology/approach: This study synthesized Zn2SnO4 nanostructures using a hydrothermal method with a 1 M concentration of zinc chloride (ZnCl2) as the zinc source and a 0.7 M concentration of tin chloride (SnCl4) as the tin source. Thick films of nanostructured Zn2SnO4 were then produced using screen printing. The structural properties of Zn2SnO4 were confirmed using X-ray diffraction, and the formation of Zn2SnO4 nanoparticles was verified by transmission electron microscopy. Scanning electron microscopy was used to analyse the surface morphology of the fabricated material, while energy dispersive spectroscopy provided insight into the chemical composition of the thick film. These fabricated thick films underwent testing for various hazardous gases, including nitrogen dioxide, ammonia, hydrogen sulphide (H2S), ethanol and methanol. Findings: The nanostructured Zn2SnO4 thick film sensor demonstrates a notable sensitivity to H2S gas at a concentration of 500 ppm when operated at 160°C. Its selectivity, response time and recovery time were assessed and documented. Research limitations/implications: The primary limitations of this research on metal oxide semiconductor gas sensors include poor selectivity to specific gases, limited durability and challenges in achieving detection at room temperature. Practical implications: The nanostructured Zn2SnO4 thick film sensor demonstrates a strong response to H2S gas, making it a promising candidate for commercial production. The detection of H2S is crucial in various sectors, including industries and sewage plants, where monitoring this gas is essential. Social implications: Currently, heightened global apprehension about atmospheric pollution stems from the existence of perilous toxic and flammable gases. This underscores the imperative need for monitoring such gases. Toxic and flammable gases are frequently encountered in both residential and industrial environments, posing substantial hazards to human health. Noteworthy accidents involving flammable gases have occurred in recent years. It is crucial to comprehend the presence and composition of these gases in the surroundings for precise detection, measurement and control. Thus, there has been a significant push for extensive research and development in diverse sensor technologies using various materials and methodologies to monitor and regulate these gases effectively. Originality/value: In this research, Zn2SnO4 nanostructures were synthesized using a hydrothermal method with ZnCl2 at a concentration of 1 M for zinc and SnCl4 at a concentration of 0.7 M for tin. Thick films of nanostructured Zn2SnO4 were then fabricated via screen printing technique. Following fabrication, all thick films were subjected to testing with various toxic gases, and the results were compared to previously published data. The analysis indicated that the nanostructured Zn2SnO4 thick film sensor demonstrated outstanding performance concerning gas response, gas concentration, selectivity and response time, particularly towards H2S gas. [ABSTRACT FROM AUTHOR]

We report the appearance of superconductivity in single-unit-cell Nd6Ni5O12, exhibiting a transition temperature similar to that of thicker films. In situ synchrotron x-ray scattering performed during growth of the parent phase, Nd6Ni5O16, shows that the necessary layer-by-layer deposition sequence does not follow the sequence of the formula unit but an alternate order due to the relative stability of the perovskite unit cell. We exploit this insight to grow ultrathin Nd6Ni5O16 heterostructures and conduct in situ studies of topotactic reduction, finding that formation of the square-planar phase occurs rapidly and is highly sensitive to reduction temperature, with small deviations from the optimum condition leading to inhomogeneity and the loss of superconductivity. The fluorite layer within the unit cell facilitates reduction by initially stabilizing the square-planar phase in the upper half of the unit cell. Our findings provide insight into growth of the Ruddlesden-Popper nickelates, highlighting the need for in situ studies of the metastable phases key to superconductivity [ABSTRACT FROM AUTHOR]

Halide perovskites hold great potential in developing next‐generation X‐ray detectors. However, preparing high‐quality and thick perovskite films in a way compatible with a thin‐film transistor (TFT)‐integrated X‐ray flat‐panel detectors (XFPDs) remains challenging. Here, by engineering ink with effective printability and shape fidelity, direct ink writing (DIW) is developed as a new approach to printing a unique single‐crystal‐assembled perovskite (SCAP) thick film. In contrast to polycrystalline grains consisting of randomly orientated crystal domains, the SCAP is made of tightly packed crystals with well‐defined crystal facets, showing 3–4 orders of magnitude lower trap density (4.48 × 1012 cm−3). Consequently, the SCAP X‐ray detectors offers the state‐of‐the‐art detection performance (sensitivity‐to‐dark current ratio: 1.26 × 1011 µC Gyair−1 A−1), a low detection limit (114.2 nGyair s−1), and negligible baseline drift (0.27 fA cm−1 s−1 V−1). Furthermore, the XFPD based on a 64 × 64 pixelated TFT array realizes high‐resolution digital radiography, opening a new avenue for further development of perovskite X‐ray detectors. [ABSTRACT FROM AUTHOR]

This study investigates the effect of polyvinylidene fluoride–CoFe2O4 (PVDF-CFO) composite film thickness on their supramolecular structure, phase composition, and dielectric properties. The composites were synthesized from PVDF with CFO nanoparticles using the Dr. Blade method to obtain film thicknesses ranging from 15 to 58 μm. The data obtained show that the thinner film (15 μm) has a higher β-phase content compared to the thicker films (58 μm), as confirmed by FTIR and Raman spectroscopy. Scanning electron microscopy (SEM) showed that increasing film thickness within the studied range leads to the development of larger spherulitic structures and increased porosity. Atomic force microscopy (AFM) analysis also showed that thicker films have higher tensile strength due to their larger cross-sectional area, while thinner films exhibit lower elasticity. A more uniform microstructure and an increased electroactive phase in thin films result in increased permittivity, which is critical for PVDF-based sensors and energy devices. [ABSTRACT FROM AUTHOR]

The present investigation provides an easy and affordable strategy for fabrication of functional ceramics Bi0.5Na0.5TiO3-SrFe12O19 (BNT-SrF5) thick films on a flexible, inexpensive and electrically integrated substrate using electrophoretic deposition process (EPD). EPD is a widely accepted, environmentally friendly method for applying coatings from a colloidal suspension to conductive substrates. Lead-free ferroelectric BNT-SrF5 powder was synthesized by solid state method to fabricate bulk samples and thick films (30–160 μm) by EPD process. Thick films were deposited onto nickel substrate by applying EPD parameters, i.e. voltage (225–290 V) and coating time (30–180 s) to acetone based colloidal suspension without aid of any dispersing agent. In a comparative analysis, both thick films and bulk ceramics revealed significant densification with sintering temperature from 1025 to 1150 °C. Fourier transform Infrared (FTIR) and X-ray diffraction (XRD) analysis revealed presence of distorted perovskite structure following calcination and sintering processes. Scanning electron microscopy (SEM) provided the surface morphologies of BNT-SrF5 powder. The dielectric constant of film sample revealed more thermal stable response compared to the bulk ceramics. Impedance spectroscopy explained the electrically active regions and hopping conduction mechanism which witnessed NTCR behavior. The potential applications for the miniaturization of electronics are sensors, actuators and energy harvesting devices. [ABSTRACT FROM AUTHOR]

The development of high‐performance organic photovoltaics (OPVs) with thick film active layers is key to moving this technology from laboratory preparation to industrial production. Design and synthesis of active layer materials to achieve a bi‐continuous interpenetrating morphology with appropriate nanoscale phase separation has been demonstrated as an effective method to realize high‐efficiency thick film devices. Here, two non‐fullerene acceptors are developed to compare the effect of symmetric (diDT‐BO) and asymmetric (DTC11‐BO) substituted alkyl chains on active layer morphology and device performance by introducing asymmetric side chains to the central core pyrrole ring. Based on the solubility and crystallinity differences of DTC11‐BO and diDT‐BO, the power conversion efficiencies (PCEs) of 19.0% and 18.1% are realized with D18 as the donor. Importantly, D18:DTC11‐BO devices with 300 and 500 nm active layers achieve excellent PCEs of 17.7% and 16.1%, which are among the top‐class values for thick film OPVs reported to date. The work demonstrates that tunning the crystallinity by optimizing the asymmetric alkyl chains is an effective material design strategy to achieve high‐efficiency thick film OPVs. [ABSTRACT FROM AUTHOR]

Improving light absorption is essential for the development of solar thermoelectric generators. Most efficient light absorbers require a back mirror (a thick metal film) to reduce the reflectivity by promoting the interference between the incident and the reflected light. However, the presence of thick a continuous metal film supposes a limitation for thermoelectric applications, as it behaves like a shortcut of the Seebeck voltage. In this work, a back mirror‐free selective light absorber is presented, designed for the fabrication of thermoelectric devices. The combination of a high and a low refractive index material covered by a semi‐transparent electrode is optimized. As a difference to the back mirror, the semi‐transparent electrode can be patterned to prevent the quenching of the Seebeck voltage. Thanks to this, the low refractive index material can be replaced by a transparent thermoelectric, enabling efficient heat‐to‐energy conversion with negligible loss of absorption performance. [ABSTRACT FROM AUTHOR]

Herein, we report the effect of film-thickness, ranging from 0.1 μm to 7.0 μm, on the energy storage performance of epitaxial Pb 0.91 La 0.09 Zr 0.7 Ti 0.3 O 3 (PLZT) films grown on silicon substrates. As the PLZT film-thickness increases, polarization is enhanced and reaches a maximum value at a film-thickness of 1.0 μm, while the breakdown-strength reaches its maximum value at 0.5 μm. A film-thickness of 1.0 μm achieves an optimal volumetric recoverable energy-storage density (U r,V) of 114.4 J/cm3 and an energy-efficiency of 87.3 % at 4.7 MV/cm. Contrastingly, a film-thickness of 4.0 μm exhibits the largest stored recoverable-energy capacity over surface-area (U r,A) of 34.2 mJ/cm2 (U r,V = 85.4 J/cm3 at 4.05 MV/cm). Moreover, a film-thickness of 4.0 μm displays a large U r,V value of 66.8 J/cm3, good thermal stability and excellent fatigue-endurance even at an operational temperature of 200 °C. These results suggest that thick PLZT films hold promise as high-performance energy-storage capacitors capable of operating effectively in harsh conditions. [ABSTRACT FROM AUTHOR]

We present α -Ga2O3:Zr based metal–semiconductor field-effect transistors (MESFETs) with PtOx/Pt gate contacts. Pulsed laser deposition is used to grow the α -Ga2O3:Zr thin films in a two-step process on m-plane α -Al2O3. A nominally undoped α -Ga2O3 layer is grown at high growth temperature as growth template. Subsequently, a α -Ga2O3:Zr layer is grown at a lower growth temperature. We compare the performance of Ring-FET devices on a planar 30 nm thick zirconium doped layer deposited at 465 °C and mesa-FETs on a 35 nm thick thin film deposited at 500 °C. The Ring-FETs have current on/off ratios as high as 1.7 × 10 9 and a threshold voltage of − 0.28 V, and they exhibit very low mean sub-threshold swing of (110 ± 20) mV/dec. For the mesa-FETs, smaller current on/off ratios of 4 × 10 7 are measured and a threshold voltage of − 1.5 V was obtained due to the larger thin film thickness. The on/off ratio is limited by a higher tunneling current in the off-regime. We present high voltage measurements, which show a breakdown of the mesa-FET device at − 340 V, corresponding to a high breakdown field of 1.36 MV/cm and significantly exceeding the previously achieved breakdown voltage for α -Ga2O3 based MESFETs. [ABSTRACT FROM AUTHOR]

ABSTRACT Polystyrene spheres ranging in diameter from 2, 5, 10, to 20 μm were embedded in five different types of thick organic films (> 50 μm) to serve as model systems to evaluate the use of time‐of‐flight secondary ion mass spectrometry for the localization and particle sizing of pharmaceuticals in orodispersible drug delivery films. It was found that certain films, such as gelatin and ethyl cellulose, are prone to developing micron‐scale topography which can affect the linearity of the sputter yield, which can ultimately affect the maximum analyzable depth. Surprisingly, the sputter yield of the film was more of a determining factor for affecting the measurement of spheres. It was possible to more accurately extract the true dimensions of the buried spheres in faster sputtering films, while slower sputtering films were associated with matrix effects and sputtering artifacts that degraded the quality of the reconstructed image. Signal attenuation was also found to be problematic and quite significant for certain film chemistries, which placed a limit on the size of the particles that could be visualized. Overall, visualization of particles embedded in thick organic films is possible, but the extraction of quantitative data such as size and the amount of material is difficult given the influence of sample dependent sputtering artifacts. [ABSTRACT FROM AUTHOR]

Inorganic CsPbBr3 perovskite emerges as a promising material for the development of next‐generation X‐ray detectors. However, the formation of a high‐quality thick film of CsPbBr3 has been challenging due to the low solubility of its precursor and its high melting point. To address this limitation, a nonstoichiometry approach is taken that allows lower‐temperature crystallization of the target perovskite under the solventless condition. This approach capitalizes on the presence of excess volatile PbBr2 within the CsPbBr3 film, which induces melting point depression and promotes recrystallization of CsPbBr3 at a temperature much lower than its melting point concomitant with the escape of PbBr2. Consequently, thick and compact films of CsPbBr3 are formed with grains ten times larger than those in the pristine films. The resulting X‐ray detector exhibits a remarkable sensitivity of 4.2 × 104 µC Gyair−1 cm−2 and a low detection limit of 136 nGyair s−1, along with exceptional operational stability. Notably, the CsPbBr3‐based flat‐panel detector achieves a high resolution of 0.65 lp pix−1 and the first demonstration of real‐time dynamic X‐ray imaging for perovskite‐based devices. [ABSTRACT FROM AUTHOR]

This study aimed to explore the influence of film thickness on the piezoelectric efficiency of polyvinylidene fluoride/graphitic carbon nitrate nanosheet (GCN) composite films, taking into account the effect of GCN alignment. Our findings demonstrated that the piezoelectric performance of these films was markedly dependent on their thickness. We have observed a direct relationship between film thickness and piezoelectric efficiency, with thicker films showing a greater capability to convert mechanical pressure into electric energy. This increased efficiency is attributed to the enhanced ability to thicker films to distribute stress uniformly across the material, which is crucial for optimizing the piezoelectric effect. Our results advance the understanding of how variation in film thickness impact mechanical properties such as stiffness and flexibility, which subsequently affect the piezoelectric response. Through predictive modeling, we analyzed the mechanical dynamics of film displacement under an electrical potential and clarified how different thickness influenced the mechanical properties and piezoelectric output. This detailed analysis deepens the fundamental understanding of material design for optimal piezoelectric performance and underscores the critical role of film thickness in engineering application. [ABSTRACT FROM AUTHOR]

Polytetrafluoroethylene (PTFE) films are deposited in parallel and perpendicular magnetic fields (MF) by electron‐enhanced vacuum deposition (EVD) and EVD + low‐temperature plasma (LTP) methods. The structure, morphology, and nanomechanical properties of the films are studied by infrared spectroscopy (IRS), atomic force microscopy (AFM), and spectroscopic ellipsometry. The structure of the thicker films is closer to that of bulk PTFE than that of thin films. The films' crystallinity and surface roughness are higher than those deposited without MF. The birefringence of the refractive index (n) of the films deposited in the MF is inverse to the anisotropy of the n of the films deposited without MF. The hardness of the films is close to that of bulk PTFE. [ABSTRACT FROM AUTHOR]

Si-doped β-phase (010) Ga2O3 epi-films with fast growth rates were comprehensively investigated using trimethylgallium (TMGa) as the Ga precursor via metalorganic chemical vapor deposition (MOCVD). Two main challenges facing the MOCVD growth of thick (010) β-Ga2O3 films with fast growth rates include high impurity carbon (C) incorporation and rough surface morphologies due to the formation of imbedded 3D pyramid-shaped structures. In this work, two different categories of oxygen source (high-purity O2 > 99.9999% and O2* with 10 ppm of [H2O]) were used for β-Ga2O3 MOCVD growth. Our study revealed that the size and density of the 3D defects in the β-Ga2O3 epi-films were significantly reduced when the O2* was used. In addition, the use of off-axis (010) Ga2O3 substrates with 2° off-cut angle leads to further reduction of defect formation in β-Ga2O3 with fast growth rates. To suppress C incorporation in MOCVD β-Ga2O3 grown with high TMGa flow rates, our findings indicate that high O2 (or O2*) flow rates are essential. Superior room temperature electron mobilities as high as 110–190 cm2/V·s were achieved for β-Ga2O3 grown using O2* (2000 sccm) with a growth rate of 4.5 μm/h (film thickness of 6.3 μm) within the doping range of 1.3 × 1018–7 × 1015 cm−3. The C incorporation is significantly suppressed from ∼1018 cm−3 to <5 × 1016 cm−3 ([C] detection limit) for β-Ga2O3 grown using high O2 (O2*) flow rate of 2000 sccm. Results from this work will provide guidance on developing high-quality, thick β-Ga2O3 films required for high power electronic devices with vertical configurations. [ABSTRACT FROM AUTHOR]

The evolutions of chip thermal management and micro energy harvesting put forward urgent need for micro thermoelectric devices. Nevertheless, low‐performance thermoelectric thick films as well as the complicated precision cutting process for hundred‐micron thermoelectric legs still remain the bottleneck hindering the advancement of micro thermoelectric devices. In this work, an innovative direct melt‐calendaring manufacturing technology is first proposed with specially designed and assembled equipment, that enables direct, rapid, and cost‐effective continuous manufacturing of Bi2Te3‐based films with thickness of hundred microns. Based on the strain engineering with external glass coating confinement and controlled calendaring deformation degree, enhanced thermoelectric performance has been achieved for (Bi,Sb)2Te3 thick films with highly textured nanocrystals, which can promote carrier mobility over 182.6 cm2 V−1 s−1 and bring out a record‐high zT value of 0.96 and 1.16 for n‐type and p‐type (Bi,Sb)2Te3 thick films, respectively. The nanoscale interfaces also further improve the mechanical strength with excellent elastic modules (over 42.0 GPa) and hardness (over 1.7 GPa), even superior to the commercial zone‐melting ingots and comparable to the hot‐extrusion (Bi,Sb)2Te3 alloys. This new fabrication strategy is versatile to a wide range of inorganic thermoelectric thick films, which lays a solid foundation for the development of micro thermoelectric devices. [ABSTRACT FROM AUTHOR]

Lead-free K 0.5 Na 0.5 NbO 3 (KNN) ferroelectric film and transparent La 0.06 Ba 0.94 SnO 3 (LBSO) bottom electrode are fabricated on (001)-oriented SrTiO 3 (STO) substrate by sol-gel. The characterization results confirm an epitaxial relationship between the films and the substrate, as well as a uniform structure and good crystallization quality of the films. The optical measurement shows that the film heterostructure exhibit a high transmittance with a maximum transmittance of ∼80 %. The polarization-electric field (P-E) curves demonstrate that the twice remanent polarization value of the ∼500 nm thick KNN film reaches up to 28 μC/cm2 under an electric field of 800 kV/cm, and the effective piezoelectric strain constant (d 33 ∗) is measured as 24.8 p.m./V. The dielectric properties of the film are displayed, and the leakage behavior can be divided into three stages of Ohmic conduction, Schottky emission and Poole-Frenkel emission with increasing the applied electric field. This study indicates that transparent lead-free ferroelectric KNN heterostructures can be prepared using a cost-effective sol-gel method and shows promise for future applications. [ABSTRACT FROM AUTHOR]

Cellulose nanomaterials have been demonstrated to be excellent barriers against grease, oxygen, and other vapors, but their implementation in packaging materials is challenging because of numerous technical and practical challenges. In this work, the oxygen, air, grease, and heptane barrier performance of copy papers coated with cellulose nanocrystals (CNCs), oxidized cellulose nanofibrils (TOCNs), and carboxymethyl cellulose (CMC) weas examined. The effects of different materials and processing conditions were evaluated for their impacts on the resulting barrier properties. TOCN coatings demonstrated significantly better barrier properties than CNC and CMC coatings due to the long-range networked structure of TOCN suspensions eliciting enhanced film formation at the paper surface. Neat coatings of nanocellulose did not readily result in strong oxygen barriers, but the addition of CMC and/or an additional waterborne water barrier coating was found to result in oxygen barriers suitable for packaging applications (1 cm3/m2·day transmission at low humidity with a 10 g/m2 coating). Cast films and thick coatings of CMC were good barriers to oxygen, grease, and air, and its addition to cellulose nanomaterial suspensions aided the coating process and reduced coating defects. In all cases, the incorporation of additional processing aids or coatings was necessary to achieve suitable barrier properties. However, maintaining the strong barrier properties of nanocellulose coatings after creasing remains challenging. [ABSTRACT FROM AUTHOR]

III‐V semiconductors are favoured photo absorber materials for solar energy conversion due to their ideal bandgap, yet their high‐cost hinders widespread adoption. Utilizing thin films of these semiconductors presents a viable way to address the cost‐related challenges. Here, a novel mechanical exfoliation technique is demonstrated, also known as controlled spalling, as a cost‐effective and facile way to obtain thin films of III‐V semiconductors. As a proof of concept, 15 μm thick InP films are successfully exfoliated from their original wafers. Thorough characterization using cathodoluminescence and photoluminescence spectroscopy confirms that the opto‐electronic properties of the exfoliated InP films remain unaffected. Utilizing these InP thin films, InP thin‐film heterojunction solar cells with efficiencies exceeding 13% are demonstrated. Additionally, InP photoanodes are fabricated by integrating NiFeOOH catalyst onto these InP thin‐film solar cells, achieving an impressive photocurrent density of 19.3 mA cm−2 at 1.23 V versus reversible hydrogen electrode, along with an applied bias photon‐to‐current efficiency of ≈4%. Overall, this study showcases the efficacy of controlled spalling in advancing economically viable and efficient III‐V semiconductor‐based solar energy conversion devices. [ABSTRACT FROM AUTHOR]

The PVDF/BST thick films were synthesized using a solution casting method. The introduction of BST into the PVDF matrix increased the dielectric constant (ε′) of the thick films. Subsequently, the pristine PVDF films and the PVDF/BST thick films underwent radiation with a 662 keV Cs1+ ion beam. Following radiation, changes were observed in the materials and their dielectric properties were studied. PVDF underwent recrystallization process accompanied by a phase shift from the α to β state. Consequently, the ε′ increased for all the PVDF-BST thick films after exposure to 662 keV Cs1+ ions, while the tangent loss also increased with increased loading of the BST filler. Notably, it is intriguing to observe that the 662 keV Cs1+ ion radiation led to a reduction in the dielectric constant, likely due to a cross-linking effect within the PVDF/BST thick films. [ABSTRACT FROM AUTHOR]

Most current laser sintering (LS) machines for polymer powders operate with a maximum bed temperature of 200 °C, limiting the use of higher melting polymers like polyethylene terephthalate (PET), which melts at ~250 °C. Using bed temperatures of ≤200 °C leads to severe part-distortion due to curl and warpage during the sintering process. The paper presents a processing method for LS at low bed temperatures, using an in situ printed anchor film to conquer curl and warpage. With the use of the anchor film, PET parts were successfully printed without machine stoppage at bed temperatures as low as 150 °C, which is about 80 °C lower than the bed temperature for a regular process for PET without the anchor film. The anchor film acts as a frictional restraint, effectively preventing the curling and warping during printing that typically result from crystallization-induced shrinkage at low bed temperatures. Whereas previous studies have employed 13 mm thick anchoring sheets bolted to the machine to prevent curl and warpage at low bed temperatures, our method uses a flexible in situ printed ~70 μm thick film to which the built part naturally adheres. The in situ printed film is easily detachable from the part after the build. The standard LS material, polyamide 12 (PA12), was also printed with lowered bed temperaturewhere the benefit would be reduced thermal degradation of the powder and decreased energy consumption during the sintering process. [ABSTRACT FROM AUTHOR]

Nickel and aluminum ohmic contacts were formed on p-doped GeC and GeCSn epitaxial films with ∼1%C. When a 40 nm p-GeC contact layer was added to p-Ge, annealed contact resistivity (Rc) dropped by 87% to 9.3 × 10−7 Ω cm2 for Al but increased by 32% to 2.9 × 10−5 Ω cm2 for Ni. On the other hand, thick films of GeCSn, which showed lower active doping, had contact resistivities of 4.4 × 10−6 Ω cm2 for Al and 1.4 × 10−5 Ω cm2 for Ni. In general, Al contacts were better than Ni, regardless of anneal, and were further improved by adding carbon. Annealing reduced Rc for both Ni and Al contacts to GeCSn by 4×, 2× for Al on GeC, and 5 orders of magnitude for Ni on GeC. It is speculated that C forms bonds with Ni that inhibit diffusion of Ni into the Ge, thus preventing the formation of low-resistance nickel germanide. Adding C, either as bulk GeCSn or as GeC contact layers, seems to significantly reduce the contact resistivity for Al contacts when compared to bulk Ge of comparable doping. [ABSTRACT FROM AUTHOR]

All‐inorganic CsPbBr3 thick films (≈10 μm) are prepared via a one‐step spray‐deposition method on TiO2‐covered fluorine doped tin oxide substrates. After carbon is pasted on top as the electrode without a hole‐transport layer in between, power conversion efficiency of 8.80% and 4.35% is achieved for large‐area solar cells (0.5 cm2) and solar modules (9.5 cm2), respectively. Tolerant to the impurity phases and rough surface morphology, the CsPbBr3 thick films fabricated through such a scalable method may serve as a platform for further construction of colorful photovoltaic cells and X‐ray‐detection devices. [ABSTRACT FROM AUTHOR]

The tribological performance of PFPE oil and the Ti:WS2/PFPE composite lubricating system with different oil amounts was investigated under a proton radiation (PR) irradiation environment. After PR irradiation, PFPE molecules occurred during cross-linking and a polymerization reaction and formed a volatile small molecular compound, which deteriorates the tribological performance of the Ti:WS2/PFPE system. The tribological properties of the Ti:WS2/PFPE system rely strongly on oil amount. For an unirradiated Ti:WS2/PFPE system, the amorphous layer of transfer film near the sliding contact area was converted into a well-defined crystalline WS2 layer with a (002) plane induced by the friction process. After PR irradiation, the transfer film became thicker and showed a wholly amorphous structure due to the difficulty in preventing the entrance of O and showed no reorientation with induced friction. [ABSTRACT FROM AUTHOR]

Decreasing the scale of vanadium dioxide (VO2) structures is one of the ways to enhance the switching speed of the material. We study the properties of VO2 films of altered thicknesses in the range of 20–170 nm prepared on c-sapphire substrates with a TiO2 sublayer by pulsed laser deposition (PLD) method. The synthesis regime to design a TiO2 film was preliminarily optimized based on XRD data. XRD patterns reveal an epitaxial growth of the VO2 films with distortion of the monoclinic cell to hexagonal symmetry. The positions of the lattice vibration modes in Raman spectra are similar to those in bulk VO2 when the film thickness is greater than ∼ 3 0 nm. For VO2 films thicker that ∼ 2 0 nm, a lattice strain results in the modes' positions and intensity change. However, the electrically triggered transition in a ∼ 5 0 nm thick VO2 film reveals forward and reverse switching times as short as 20 ns and 400 ns, correspondingly. [ABSTRACT FROM AUTHOR]

An ultra-thin spiral diffractive lens (SDL) was fabricated by using focused ion beam milling on a fiber end-facet coated with a 100 nm thick Au film. Focusing vortex beams (FVBs) were successfully excited by the SDLs due to the coherent superposition of diffracted waves and their azimuth dependence of the phase accumulated from the spiral aperture to the beam axis. The polarization and phase characteristics of the FVBs were experimentally investigated. Results show that the input beams with various polarization states were converted to FVBs, whose polarization states were the same as those of the input beams. Furthermore, the focal length of the SDL and the in-tensity and phase distribution at the focus spot of the FVBs were numerically simulated by the FDTD method in the ultra-wide near-infrared waveband from 1300 nm to 1800 nm. The focal length was tuned from 21.8 μm to 14.7 μm, the intensity profiles exhibited a doughnut-like shape, and the vortex phase was converted throughout the broadband range. The devices are expected to be candidates for widespread applications including optical communications, optical imaging, and optical tweezers. [ABSTRACT FROM AUTHOR]

Temperature sensors play important roles in wide-spreading human activities. The non-contact method of using temperature sensors offers significant advantages but faces challenges in detection precision. In this work, a double-layer asymmetric terahertz (THz) metamaterial combined with phase transition oxide was proposed to realize non-contact temperature sensor with high sensitivity. The metamaterial exhibited band-stop filtering effects in the simulated transmission spectra. Temperature changes induced a reversible phase transition in VO2, resulting in altered conductivity. The numerical results indicated that the S21 parameter increases from −44.33 dB to −4.78 dB at a frequency of 1.22 THz as the conductivity of the VO2 film increases from 10 to 5000 S/m, achieving a modulation depth of 89%. In addition, the 86 nm thick VO2 film underwent a phase transition in the temperature range of 54.93 °C to 66.93 °C, achieving a sensitivity of 1.82 dB/°C for temperature sensing. This work provided great insights into the development of metamaterials based on high-precision temperature measurement. [ABSTRACT FROM AUTHOR]

This work investigates the endurance and performance of aluminum-doped zinc oxide (AZO) thin films fabricated on flexible polyethylene terephthalate (PET) substrates, providing new insights into their degradation linked to mechanical flexing and accelerated thermal cycling (ATC). The current study uniquely combines cyclic bending fatigue at 23 °C and 70 °C with ATC between 0 °C and 100 °C, simulating operational stresses in real-world environments, in contrast to previous research that has focused primarily on either isolated mechanical or thermal effects. The 425 nm thick films showed high transparency and conductivity, making them suitable materials for flexible electronics and optoelectronic devices. In this work, electrical resistivity, one of the most important performance parameters, was investigated after each mechanical or thermal cycle. The results indicate that mechanical cycling at high temperatures can drastically enhance the crack formation and electrical degradation, with an over 250% change in the electrical resistance (PCER) after 12,000 cycles at 70 °C and more than 300% after 500 thermal cycles. The highly deleterious effects of combined stressors on the structural integrity and electrical properties of AZO films are underlined by these observations. This study further suggests that the design of more robust AZO-based materials/coatings would contribute toward achieving better durability in flexible electronic applications. These findings also go hand in glove with the ninth goal of the United Nations' Sustainable Development Goals, specifically Target 9.5: Enhance Research and Upgrade Industrial Technologies. [ABSTRACT FROM AUTHOR]