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Herein, a model is proposed for measuring the structural defects size r0 in an ultrathin magnetic layer with perpendicular magnetic anisotropy. Based on the observations of magnetic domains in Ta/Pt/Co/Pt ultrathin films, using polar magneto‐optical Kerr effect microscopy and measurements of their magnetic anisotropies, the correlation between magnetic domains size D and structural defects size r0, as well as the defects concentration parameter αK, which designates the degree of pinning, has been modeled. The average r0 value found is high in the sample with unannealed buffer layers and considerably decreases with annealing. It is 6.17 nm with unannealed Ta/Pt buffer layers, 1.06 nm in sample with Ta/Pt buffer layers annealed at 423 K, and 0.49 nm in that with buffer layers annealed at 573 K. The significant drop of r0 is in good agreement with the high depinning noted with buffer layers annealing in recent work. [ABSTRACT FROM AUTHOR]

Off-stoichiometric NixFe3−xO4 ultrathin films (x < 2.1) with varying Ni content x and thickness 16 (±2) nm were grown on MgO(001) by reactive molecular beam epitaxy. Synchrotron-based high-resolution X-ray diffraction measurements reveal vertical compressive strain for all films, resulting from a lateral pseudomorphic adaption of the film to the substrate lattice without any strain relaxation. Complete crystallinity with smooth interfaces and surfaces is obtained independent of the Ni content x. For x < 1 an expected successive conversion from Fe3O4 to NiFe2O4 is observed, whereas local transformation into NiO structures is observed for films with Ni content x > 1. However, angle-resolved hard X-ray photoelectron spectroscopy measurements indicate homogeneous cationic distributions without strictly separated phases independent of the Ni content, while X-ray absorption spectroscopy shows that also for x > 1, not all Fe 2 + cations are substituted by Ni 2 + cations. The ferrimagnetic behavior, as observed by superconducting quantum interference device magnetometry, is characterized by decreasing saturation magnetization due to the formation of antiferromagnetic NiO parts. [ABSTRACT FROM AUTHOR]

As a result of theoretical considerations on the study of the influence of the phonon quasiparticle subsystem on the thermal capacitance of a two-dimensional quasicrystal in the form of an ultrathin film, an exact formula for the thermal capacitance of an ideal ultrathin film, valid over the entire temperature range, is derived in this paper. The dispersion equation as well as the possible phonon energies and allowed phonon states were determined by the method of Green's functions. The obtained formula for the thermal capacitance of the ultrathin film is plotted and compared with the corresponding graphs representing massive crystalline structures in both the low-temperature and high-temperature regions. The conclusions that can be drawn are highly consistent with recent results related to the possibility of realizing high-temperature superconductivity. [ABSTRACT FROM AUTHOR]

Developing a method for the growth of ultrathin metal chalcogenides, potentially targeting the two-dimensional (2D) limit, has a pivotal impact on various nanotechnological device applications. Here, we employed a vapor deposition scheme, based on tellurization, to induce the heterogenous chemical reaction between solid Ag and Au precursors, in the form of ultrathin films, and Te vapors. We characterized the morphological and structural properties of the grown tellurides by using atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction techniques. The developed tellurization methodology provides a key advancement in the picture of growing ultrathin noble metal tellurides and holds great potential for applications in different technological fields. [ABSTRACT FROM AUTHOR]

Self‐powered UV sensing has enormous potential in military and civilian applications. However, achieving high responsivity and fast response/recovery time presents significant challenges. Self‐powered photodetectors (PDs) have several advantages over traditional PDs, including higher sensitivity, lower power consumption, and simpler design. This study introduces a breakthrough self‐powered PD that uses a Schottky junction of 2D α‐MoO3/iridium (Ir)/Si ultrathin film to detect 365 nm light at 0 V bias through using atomic layer deposition (ALD) and sputtering systems. The PD response is enhanced by plasmonic Ir‐induced hot carriers, enabling detection in a mere 0.1 ms. Incorporating a 4 nm Ir layer boosts the responsivity from 0 to 34 A W−1, and the external quantum efficiency is elevated from 0 to 7E11 under 365 nm light illumination. It also has a high ION/IOFF ratio of 11.22E4 at 0 V. These results make the MoO3/4 nm Ir/Si structure an interesting option for self‐powered PDs with high efficiency, and the use of a simple ALD system for large‐scale fabrication of 2D α‐MoO3 on hot carrier Ir plasmonic layer. The findings of this research hold tremendous promise in the field of UV sensing and can lead to exciting developments in military and civilian technology. [ABSTRACT FROM AUTHOR]

Ultrathin Co x Fe 3 − x O 4 films of high structural quality and with different Co content (x = 0.6–1.2) were prepared by reactive molecular beam epitaxy on MgO(001) substrates. Epitaxy of these ferrite films is extensively monitored by means of time-resolved (operando) X-ray diffraction recorded in out-of-plane geometry to characterize the temporal evolution of the film structure. The Co ferrite films show high crystalline ordering and smooth film interfaces independent of their Co content. All Co x Fe 3 − x O 4 films exhibit enhanced compressive out-of-plane strain during the early stages of growth, which partly releases with increasing film thickness. When the Co content of the ferrite films increases, the vertical-layer distances increase, accompanied by slightly increasing film roughnesses. The latter result is supported by surface-sensitive low-energy electron diffraction as well as X-ray reflectivity measurements on the final films. In contrast, the substrate–film interface roughness decreases with increasing Co content, which is confirmed with X-ray reflectivity measurements. In addition, the composition and electronic structure of the ferrite films is characterized by means of hard X-ray photoelectron spectroscopy performed after film growth. The experiments reveal the expected increasing Fe 3 + / Fe 2 + cation ratios for a higher Co content. [ABSTRACT FROM AUTHOR]

The development of the new generation of non-volatile high-density ferroelectric memory requires the utilization of ultrathin ferroelectric films. The most promising candidates are polycrystalline-doped HfO2 films because of their perfect compatibility with silicon technology and excellent ferroelectric properties. However, the remanent polarization of HfO2 films is known to degrade when their thickness is reduced to a few nanometers. One of the reasons for this phenomenon is the wake-up effect, which is more pronounced in the thinner the film. For the ultrathin HfO2 films, it can be so long-lasting that degradation occurs even before the wake-up procedure is completed. In this work, an approach to suppress the wake-up in ultrathin Hf0.5Zr0.5O2 films is elucidated. By engineering internal built-in fields in an as-prepared structure, a stable ferroelectricity without a wake-up effect is induced in 4.5 nm thick Hf0.5Zr0.5O2 film. By analysis of the functional characteristics of ferroelectric structures with a different pattern of internal built-in fields and their comparison with the results of in situ piezoresponse force microscopy and synchrotron X-ray micro-diffraction, the important role of built-in fields in ferroelectricity of ultrathin Hf0.5Zr0.5O2 films as well as the origin of stable ferroelectric properties is revealed. [ABSTRACT FROM AUTHOR]

While the bulk strontium titanate (STO) crystal characteristics are relatively well known, ultrathin perovskites' nanostructure, chemical composition, and crystallinity are quite complex and challenging to understand in detail. In our study, the DFT methods were used for modelling the Raman spectra of the STO bulk (space group I4/mcm) and 5–21-layer thin films (layer group p4/mbm) in tetragonal phase with different thicknesses ranging from ~0.8 to 3.9 nm. Our calculations revealed features in the Raman spectra of the films that were absent in the bulk spectra. Out of the seven Raman-active modes associated with bulk STO, the frequencies of five modes (2Eg, A1g, B2g, and B1g) decreased as the film thickness increased, while the low-frequency B2g and higher-frequency Eg modes frequencies increased. The modes in the films exhibited vibrations with different amplitudes in the central or surface parts of the films compared to the bulk, resulting in frequency shifts. Some peaks related to bulk vibrations were too weak (compared to the new modes related to films) to distinguish in the Raman spectra. However, as the film thickness increased, the Raman modes approached the frequencies of the bulk, and their intensities became higher, making them more noticeable in the Raman spectrum. Our results could help to explain inconsistencies in the experimental data for thin STO films, providing insights into the behavior of Raman modes and their relationship with film thickness. [ABSTRACT FROM AUTHOR]

One of the unsolved problems for using high‐Tc superconducting cuprates for spintronic applications are the short coherence lengths of Cooper pairs in oxides (a few Å), which requires atomically sharp and defect‐free interfaces. This research demonstrates the presence of high‐Tc superconducting La1.84Sr0.16CuO4 in direct proximity to SrLaMnO4 and provides evidence for the sharpness of interfaces between the cuprate and the manganite layers at the atomic scale. These findings shed light on the impact of the chemical potential at the interface of distinct materials on highly sensitive physical properties, such as superconductivity. Additionally, this results show the high stability of ultrathin layers from the same K2NiF4‐type family, specifically one unit cell of Sr2−xLaxMnO4 and three unit cells of La1.84Sr0.16CuO4. This work advances both the fundamental understanding of the proximity region between superconducting cuprates and manganite phases and the potential use of oxide‐based materials in quantum computing. [ABSTRACT FROM AUTHOR]

Due to their high electromechanical coupling and energy density properties, ultrathin piezoelectric films have recently been intensively studied as key materials for the construction of miniaturized energy transducers, and in this paper we summarize the research progress. At the nanoscale, even a few atomic layers, ultrathin piezoelectric films have prominent shape anisotropic polarization, that is, in-plane polarization and out-of-plane polarization. In this review, we first introduce the in-plane and out-of-plane polarization mechanism, and then summarize the main ultrathin piezoelectric films studied at present. Secondly, we take perovskite, transition metal dichalcogenides, and Janus layers as examples to elaborate the existing scientific and engineering problems in the research of polarization, and their possible solutions. Finally, the application prospect of ultrathin piezoelectric films in miniaturized energy converters is summarized. [ABSTRACT FROM AUTHOR]

Ultrathin MoO3 semiconductor nanostructures have garnered significant interest as a promising nanomaterial for transparent nano- and optoelectronics, owing to their exceptional reactivity. Due to the shortage of knowledge about the electronic and optoelectronic properties of MoO3/n-Si via an ALD system of few nanometers, we utilized the preparation of an ultrathin MoO3 film at temperatures of 100, 150, 200, and 250 °C. The effect of the depositing temperatures on using bis(tbutylimido)bis(dimethylamino)molybdenum (VI) as a molybdenum source for highly stable UV photodetectors were reported. The ON–OFF and the photodetector dynamic behaviors of these samples under different applied voltages of 0, 0.5, 1, 2, 3, 4, and 5 V were collected. This study shows that the ultrasmooth and homogenous films of less than a 0.30 nm roughness deposited at 200 °C were used efficiently for high-performance UV photodetector behaviors with a high sheet carrier concentration of 7.6 × 1010 cm−2 and external quantum efficiency of 1.72 × 1011. The electronic parameters were analyzed based on thermionic emission theory, where Cheung and Nord's methods were utilized to determine the photodetector electronic parameters, such as the ideality factor (n), barrier height (Φ0), and series resistance (Rs). The n-factor values were higher in the low voltage region of the I–V diagram, potentially due to series resistance causing a voltage drop across the interfacial thin film and charge accumulation at the interface states between the MoO3 and Si surfaces. [ABSTRACT FROM AUTHOR]

Co/CoO multilayers are fabricated by means of radio-frequency magnetron sputtering. For the formation of each multilayer period, a Co layer is initially produced followed by natural oxidation. Platinum is used not only as buffer and capping layers, but also in the form of intermediate ultrathin layers to enhance perpendicular magnetic anisotropy. Three samples are compared with respect to the magnetic anisotropies and exchange bias between 4–300 K based on superconducting quantum interference device magnetometry measurements. Two of the multilayers are identical Co/CoO/Pt ones; one of them, however, is grown on a Co/Pt "magnetic substrate" to induce perpendicular magnetic anisotropy via exchange coupling through an ultrathin Pt intermediate layer. The third multilayer is of the form Co/CoO/Co/Pt. The use of a "magnetic substrate" results in the observation of loops with large remanence when the field applies perpendicular to the film plane. The CoO/Co interfaces lead to a significant exchange bias at low temperatures after field cooling. The largest exchange bias was observed in the film with double Co/CoO/Co interfaces. Consequently, significant perpendicular anisotropy coexists with large exchange bias, especially at low temperatures. Such samples can be potentially useful for applications related to spintronics and magnetic storage. [ABSTRACT FROM AUTHOR]

Harvesting sustainable energy opens new avenues for powering portable electronic devices using triboelectric nanogenerators (TENGs). Synthetic metals and polymers are used to construct most of the TENGs. Hence, ultrathin, free‐standing, translucent, and chemically bonded chitosan (CH)‐ and alginate (AL)‐based biopolymeric films are introduced here. These films are fabricated using a low‐cost and environmentally friendly layer‐by‐layer (LbL) self‐assembly method and impregnated with AgNO3 (S) in the final fabrication step (denoted as [(CH/AL)n:(CHS/AL)1]n+1). The LbL‐assembled film displays remarkable antimicrobial and triboelectric properties, demonstrating a new type of TENG that is implantable in the body. By varying the number of CH and AL depositions, the dependence of TENG behaviors on thickness is investigated. It is demonstrated that a 0.87‐µm‐thick [CH/AL]8 TENG resulted in the highest electrical output performance of 474 V and 36.9 mA m−2 due to the highest surface potential and the lowest work function of 239.4 mV and 4.2 eV, respectively. A free‐standing [(CH/AL)49:(CHS/AL)1]50 TENG is designed for antimicrobial skin‐patchable shape‐adaptive nanogenerators, displaying ultrahigh translucency, long‐term mechanical stability, and exceptional versatility. It is then attached to the arm to detect external stimuli, and the feasibility of its use as an encodable skin‐touch sensor is demonstrated. [ABSTRACT FROM AUTHOR]

[Display omitted] Super broadband optical absorbers with ultrathin films have been keenly pursued for a long time. Although highly lossy materials with sharp light attenuation have the potential to become super absorbers, a large percent of light from free space is inevitably reflected back for the distinct impedance mismatch. Here, a simple strategy, of which reducing the thickness of highly-lossy thin films to minish reflectance and simultaneously folding the ultrathin films to make light multiple pass through, is proposed to obtain super broadband mid-infrared absorbers with ultrathin films. Along this line, the absorbers were prepared by depositing Al-doped ZnO film on scaffolds consisted of alumina spherical shells, whose substrates were opaque. When the thickness of Al-doped ZnO is 43 nm and the layer number of scaffolds is three, a maximum average absorptance was achieved as 97.6% over the wavelength range from 3 to 15 μm. Applying this strategy on polished Al foil, excellent infrared camouflage performance on human-body background was demonstrated. Featured by the strong broadband optical absorption with ultrathin films, flexible access to multiple substrates and low-cost procedures, this approach has the potential in widespread applications of infrared thermal emitters and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Synergistic methodological strategies based on the fields of microbial biotechnology and materials science open up an enormous range of possibilities for the sustainable production of advanced materials with predictable properties. This study shows how naturally produced polyhydroxyalkanoate (PHA) particles are introduced into bacterial cellulose (BC) driven by their bacterial producers. Thanks to an extensive knowledge of the internal structure of BC, it was possible to control the colonization process, i.e. loading and localization of PHA. A subsequent acid treatment favored the PHA-BC bonding at the position reached by the bacteria. These biodegradable films showed improved mechanical and barrier properties even with respect to reference plastic films 8 times thicker, reaching a Young's modulus 4.25 times higher and an oxygen permeability 3 times lower than those of polyethylene terephthalate (PET) films. Owing to the versatility of the method, a wide variety of materials can be developed for very diverse fields of application. [Display omitted] • PHA particles are introduced into BC driven by their bacterial producers. • The colonization process was controlled, i.e. loading and localization of PHA. • PHA-BC bonding was stabilized by hydrogen bonding in the position reached by bacteria. • Films showed 3 times better barrier properties than 8 times thicker PET films. • The high versatility of this method allows the customization of film properties. [ABSTRACT FROM AUTHOR]

The interest in ultrathin silver (Ag) films has increased due to their high surface plasmon resonance for coatings of only a few nm. Low roughness ultrathin films of 1 to 9 nm have been deposited on different substrates, such as polyethylene terephthalate (PET) and optical glass, using radio frequency (RF) magnetron sputtering. Films show good surface plasmon resonance up to 7 nm thickness, as revealed by the ultraviolet-visible (UV-Vis) spectra. The roughness of the films, investigated by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM), is small, and one can conclude that depositions are smooth and homogeneous. The bandgap values decrease with film thickness. The refractive index of the films, calculated from ellipsometry measurements, leads to values of under 1 visible domain, with minima in the wavelength range of 400–600 nm. The results are useful for obtaining lower roughness ultrathin Ag films with good surface plasmon resonance for photonic applications. [ABSTRACT FROM AUTHOR]

Superconducting nanofilms are tunable systems that can host a 3D–2D dimensional crossover leading to the Berezinskii–Kosterlitz–Thouless (BKT) superconducting transition approaching the 2D regime. Reducing the dimensionality further, from 2D to quasi-1D superconducting nanostructures with disorder, can generate quantum and thermal phase slips (PS) of the order parameter. Both BKT and PS are complex phase-fluctuation phenomena of difficult experiments. We characterized superconducting NbN nanofilms thinner than 15 nm, on different substrates, by temperature-dependent resistivity and current–voltage (I-V) characteristics. Our measurements evidence clear features related to the emergence of BKT transition and PS events. The contemporary observation in the same system of BKT transition and PS events, and their tunable evolution in temperature and thickness was explained as due to the nano-conducting paths forming in a granular NbN system. In one of the investigated samples, we were able to trace and characterize the continuous evolution in temperature from quantum to thermal PS. Our analysis established that the detected complex phase phenomena are strongly related to the interplay between the typical size of the nano-conductive paths and the superconducting coherence length. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thin copper films (20 nm) were deposited via thermal evaporation, with variations in substrate temperature (T s = RT, 330 K, and 390 K). • Films deposited at 330 K exhibited the smallest percolation thickness (12 nm) and aging rates due to their compact morphology, showcasing lower surface roughness (δ) and correlation length (ξ). • Immersion of the films in a dodecanethiol solution (1 mM) in ethanol resulted in significant resistance increment, ranging from 0.1 % to 0.4 %. • By depositing a chromium surfactant layer, the impact of the electron-surface scattering mechanism on resistivity was amplified, leading to a resistance increase of up to 1.2% due to thiols adsorption. • The negatively charged S-head of the adsorbed thiols on the copper oxide surface, altering the charge balance below the Cu 2 O/Cu interface, enhancing the electrical resistance. The impact of thiol adsorption on thin copper films, covered with a copper oxide layer, was investigated using electrical resistance measurements at various stages: during film growth, aging, exposure to air, and immersion in thiol solutions. Thin copper films (20 nm) were thermally evaporated, with variations in substrate temperature (RT, 330 and 390 K). Films deposited at 330 K exhibited the smallest percolation thickness and aging rates due to their compact morphology, showcasing lower surface roughness and correlation length. Exposure to air led to the formation of a Cu 2 O layer on the film surface. Subsequent immersion in a dodecanethiol solution in ethanol resulted in a resistance increase, ranging from 0.1 % to 0.4 %. This change was dependent on the substrate temperature, with the largest difference observed at 330 K. This observation suggests that samples grown at this temperature exhibited the highest electron-surface scattering. Moreover, by depositing a chromium surfactant layer, the impact of this scattering mechanism was amplified, leading to a resistance increase of up to 1.2 %. Mayadas-Shatzkes theory provided a good description of these resistance changes. The negatively charged S-head of the adsorbed thiols alters the electric field experienced by conduction electrons in the Cu 2 O/Cu interface, modifying the electron-surface scattering. [ABSTRACT FROM AUTHOR]

• Diethylzinc dose reduction while doping drives structural and morphological changes. • Al content results almost invariant despite diethylzinc reduction in doping-cycles. • Optoelectronic behavior reveals electronic and defect contributions from Al-doping. Transparent conductive oxides are trending topic in science and technology due to counterintuitive properties: optical transparency and high electrical conductivity. ZnO is a promising example with optoelectronic properties enhanced by supervalent doping. Al-doped ZnO (AZO) has emerged as leading candidate to replace environmentally hazardous In-doped SnO 2. However, an ongoing debate exists regarding whether Al-doping improves its optoelectronic properties by substitutional doping or by promoting active defects. Here, we focused on Al-doping of ZnO by atomic layer deposition (ALD) applying the supercycle approach, showing that, decreasing Zn precursor dosing during dopant cycles, the decreasing saturation degree of Zn-species monolayers leads to morphological and microstructural changes that negatively impact optoelectronic properties, whereas Al content remains invariant. Our results demonstrate that unsaturated surfaces after decreasing Zn precursor dosing play a crucial role in Al incorporation, suggesting that, to maximize the effect of doping, complete oxide substitution reactions rather than those of conventional ALD must control growth, while crystallinity must remain. These findings could impact strategy designing for optimization of optoelectronic properties of AZO films deposited by ALD by inclining the debate towards the hypothesis that electrical properties are determined by Al substitutional doping together with active defects formed due to substitutional doping itself. [ABSTRACT FROM AUTHOR]

We present two ideas to simplify the measurement and analysis of terahertz time-domain spectroscopic ellipsometry data of ultrathin films. The measurement is simplified by using a specially designed sample holder with mirrors, which can be mounted on a cryostat. It allows us to perform spectroscopic ellipsometry by simply inserting the holder into a conventional terahertz spectroscopy system for measurements in transmission geometry. The analysis of the obtained data is simplified by considering a single interface with a certain sheet conductivity σs\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\sigma }_{s}$$\end{document} (since the film thickness is significantly smaller than the wavelength of the terahertz light). We demonstrate the application of these ideas by evaluating the sheet conductivities of two perovskite rare-earth nickelate thin films in the temperature range 78–478 K. The use of this particular analytical method and the sample holder design will help to establish terahertz time-domain spectroscopic ellipsometry as a characterization technique for ultrathin films. [ABSTRACT FROM AUTHOR]

In this work, we investigated the influence of oxygen plasma on the growth of nickel cobaltite (NiCo2O4) thin films compared to growth in a molecular oxygen atmosphere. The films were grown on MgO(001), MgAl2O4(001) and SrTiO3(001) substrates by oxygen plasma (atmosphere of activated oxygen)-assisted and reactive molecular beam epitaxy (molecular oxygen atmosphere). Soft X-ray photoelectron spectroscopy showed that only the use of oxygen plasma led to a spectrum characteristic of (NiCo2O4). Low energy electron diffraction measurements were conducted to obtain information on the structure of the film surfaces. The results proved the formation of a spinel surface structure for films grown with oxygen plasma, while the formation of a rock salt structure was observed for growth with molecular oxygen. To determine the film thickness, X-ray reflectivity measurements were performed. If oxygen plasma were used to grow (NiCo2O4) films, this would result in lower film thicknesses compared to growth using molecular oxygen although the cation flux was kept constant during deposition. Additional X-ray diffraction experiments delivered structural information about the bulk structure of the film. All films had a rock salt bulk structure after exposure to ambient conditions. Angle-resolved hard X-ray photoelectron spectroscopy revealed a homogeneous depth distribution of cations of the grown film, but no typical (NiCo2O4) spectrum anymore. Thus, on the one hand, (NiCo2O4) films with a spinel structure prepared using activated oxygen were not stable under ambient conditions. The structure of these films was transformed into NiCo oxide with a rock salt structure. On the other hand, it was not possible to form (NiCo2O4) films using molecular oxygen. These films had a rock salt structure that was stable under ambient conditions. [ABSTRACT FROM AUTHOR]

Hybrid materials compose a new class of nanostructured free- or bound-disperse systems that combine organic and inorganic components in their composition. The properties of the hybrid materials are governed by the known colloid-chemical regularities. The phenomenon of the synergism in the properties of such materials is realized due to the interaction between system components at interfaces and depends on the structural order of the systems. In the last decade, a new field of researches has appeared, i.e., supramolecular self-assembly, which implies the simultaneous or successive integration of components into a unified structure via the formation of numerous noncovalent (hydrogen, ionic, coordination, etc.) bonds. This review lets readers get acquainted with different types of supramolecular self-assembly of hybrid nanosystems at interfaces. The methods of forming hybrid systems are discussed by the examples of mixtures of classical cationic surfactants and functionalized zinc porphyrinates used as organic linkers in combination with spherical metal nanoparticles and planar inorganic matrices (graphene oxide and layered hydroxides of rare-earth metals). The relation between the structure and properties of hybrid materials are considered in detail, and the possible practical applications and the perspectives of the development of this field of colloid chemistry for the nearest decade are discussed. [ABSTRACT FROM AUTHOR]

This study reports the first fully additively manufactured capacitors as a proof‐of‐concept demonstration of direct‐write, ultrathin‐film electronic components made via multi‐material microplasma sputtering. This is also the first demonstration of a cleanroom‐quality, multi‐material electrical device produced entirely through additive manufacturing. Ultrathin metal and dielectric films are deposited at <80 °C and atmospheric pressure conditions on a substrate using a novel, continuously fed, dual target microsputtering printhead. The conductive films are created by sputtering gold in an air atmosphere and shown to attain near‐bulk electrical resistivity. The dielectric films are created by sputtering aluminum in a gas blend of argon and air; the aluminum oxidizes in the high‐energy, high‐collisionality plasma, forming alumina nanoparticles that are deposited on the substrate. Ultra‐thin (35 nm) alumina films showed extremely high resistivity (100 GΩ‐m) and dielectric strength (6.2 GV m−1). Also, the frequency response of the capacitor is satisfactorily described by the universal dielectric response typically found in heterogenous dielectrics. It is hypothesized that the dielectric response is the result of the presence of condensed water in the pores of the alumina film. [ABSTRACT FROM AUTHOR]

Herein, the crystalline and electronic structures of ultrathin cadmium sulfide {0001} films with thickness ranging from 1 to 14 Cd–S bilayers are studied using first‐principles calculations method. After structural relaxation, the film composed of 1 Cd–S bilayer is transformed into a CdS monolayer with flat honeycomb structure. Those 2‐ to 5‐bilayer films do not maintain the Wurtzite structure either: the distance between the sulfur and cadmium layers in each bilayer is compressed while the Cd–S bond length between adjacent bilayers is enlarged. These 1‐ to 5‐bilayer films reveal semiconducting characteristics in band structures, and their bandgaps are widened in some degree compared with the bulk. The films with 6–14 Cd–S bilayers keep the Wurtzite structure of the bulk, and exhibit metallic surface states due to the polarity of the films. The results could provide a new insight for the electronic structure regulation of cadmium sulfide. [ABSTRACT FROM AUTHOR]

Perovskite solar cells have potential to deliver terawatt‐scale power via low‐cost manufacturing. However, scaling is limited by slow, high‐temperature annealing of the inorganic transport layers and the lack of reliable, large‐area methods for depositing thin (<30 nm) charge transport layers (CTLs). We present a method for scaling ultrathin NiOx hole transport layers (HTLs) by pairing high‐speed (60 m min−1) flexographic printing with rapidly annealed sol–gel inks to achieve the fastest reported process for fabrication of inorganic CTLs for perovskites. By engineering precursor rheology for rapid film‐leveling, NiOx HTLs were printed with high uniformity and ultralow pinhole densities resulting in photovoltaic performance exceeding that of spin‐coated devices. Integrating these printed transport layers in planar inverted PSCs allows rapid fabrication of high‐efficiency (PCE > 15%) CsxFA1−xPbI solar cells with improved short circuit currents (Jsc) of 22.4 mA cm−2. Rapid annealing of the HTL accelerates total processing time by 60X, while maintaining the required balance of optoelectronic properties and the chemical composition for effective hole collection. These results build an improved understanding of ultrathin NiOx and reveal opportunities to enhance device performance via scalable manufacturing of inorganic CTLs. [ABSTRACT FROM AUTHOR]

Smooth and uniform epitaxial ultrathin MgB2 films are desired for various electronic applications including hot-electron bolometers and single-photon detectors. However, the growth of ultrathin MgB2 films on SiC substrates using the Hybrid Physical-Chemical Vapor Deposition was dominated by the Volmer-Weber or island growth mode, which limited the minimum thickness for a conductive MgB2 film. Here we show the results of a study on the very early stage of the MgB2 film growth. We find that the root-mean-squared roughness and grain connectivity of ultrathin MgB2 films grown on C-terminated 6H-SiC($000\bar{1}$) substrate is much better than those on Si-terminated substrate. The result provides a simple solution to growing high-quality ultrathin MgB2 films for applications. [ABSTRACT FROM AUTHOR]

The crystalline component and crystallization morphology of poly(vinylidene fluoride‐chlorotrifluoroethylene) (P(VDF‐CTFE)) ultrathin film have been investigated. The CTFE segment has been characterized as the crystal composition of the film. For the film on the Si substrate, the nucleation behavior is dominated by homogeneous nucleation to form edge‐on lamellae in the initial stage of crystal nucleation growth. The edge‐on lamella will continue to grow at high crystallization temperature (Tc). However, it will be transformed into flat‐on lamellae at low Tc. For the film on Au substrate, the primary nucleation rate of the layer near the film surface has a competitive relationship when compared with the primary nucleation rate of the layer near the film/substrate interface. The nucleation behavior is preferentially dominated by heterogeneous nucleation to form flat‐on lamellae at high Tc. But it is conducive to homogeneous nucleation to form edge‐on lamellae at low Tc. Further investigation suggests that the different crystalline morphologies of P(VDF‐CTFE) ultrathin film obtained on Au and Si surfaces are closely related to the different interface effects between the film and the substrates. It is anticipated that this study will cast new light on the rational regulation of the morphologies of ultrathin films. [ABSTRACT FROM AUTHOR]

Sputtering is an effective technique for producing ultrathin films with diverse applications. The review begins by providing an in-depth overview of the background, introducing the early development of sputtering and its principles. Consequently, progress in advancements made in recent decades highlights the renaissance of sputtering as a powerful technology for creating thin films with varied compositions, structures, and properties. For the first time, we have discussed a thorough overview of several sputtered thin film materials based on metal and metal oxide, metal nitride, alloys, carbon, and ceramic-based thin film along with their properties and their applicability in various fields. We further delve into the applications of sputter-coated thin films, specifically emphasizing their relevance in environmental sustainability, energy and electronics, and biomedical fields. We critically examine the recent advancements in developing sputter-coated catalysts for eliminating water pollutants andhydrogen generation. Additionally, the review sheds light on advantages, shortcomings, and future directions for developing sputter-coated thin films utilized in biodegradable metals and alloys with enhanced corrosion resistance and biocompatibility. This review is a comprehensive integration of recent literature, covering diverse sputtering thin film applications. We delve deeply into various material types and emphasize critical analysis of recent advancements, particularly in environmental, energy, and biomedical fields. By offering insights into both advancements and limitations, the review provides a nuanced understanding essential for practical utilization. [Display omitted] • The development of thin film by sputtering technology is reviewed. • Advances in thin films as the solution for environmental sustainability and energy are summarized. • The progress that has been made on thin film for biomedical devices so far is promising. • Challenges and perspectives for industrialization are highlighted. [ABSTRACT FROM AUTHOR]

[Display omitted] • Annealing amorphous carbon films on a metal film catalyzes sp 2 graphene formation. • Thermal annealing favors graphene formation in sp 3-rich amorphous carbon films. • The content of carbon atoms within the catalyst influences graphene formation. • Metal sublayers with less occupied d -shells promote graphene nucleation. The exceptional properties of graphene, such as mechanical strength, flexibility, thermal conductivity, electron mobility, biocompatibility, and transparency, make it an ideal material for numerous applications. The objective of this study was to develop a one-step process of graphene formation that uses inert thermal annealing of amorphous carbon (a -C) ultrathin films deposited onto different metal catalyst sublayers to transform highly sp 3 hybridized a -C nanostructures within the film to sp 2 hybridized graphene nanostructures. To elucidate the mechanism of graphene formation and the catalytic effect of the sublayers on sp 3-to- sp 2 transformation, Si/FeNi/ a -C and Si/FeCo/ a -C stacks were fabricated by physical vapor deposition techniques. X-ray photoelectron and Raman spectroscopies were used to analyze the structure of as-deposited and thermally annealed a -C films. Moreover, molecular dynamics simulations provided insight into graphenization at the atomic level. The sp 3 fraction of as-deposited a -C films was found to play a pivotal role in the formation of graphene during thermal annealing. The carbon concentration in the catalyst sublayers and the compressive stress in the a -C films strongly affected atomic carbon hybridization and, consequently, the graphene quality. Differences in the catalytic effectiveness of the sublayers in producing graphene are interpreted in terms of the sublayer carbon concentration, atomic packing, and electronic structure of the valence band of elements affecting the interaction between carbon and transition metals, ultimately influencing graphene nucleation. [ABSTRACT FROM AUTHOR]

In this work, we present a comprehensive study on real-time monitoring the growth of epitaxial CoxFe3−xO4 thin films grown on SrTiO3(001) substrates via reactive molecular beam epitaxy. The growth process was monitored during evaporation by means of time resolved operando hard X-ray photoelectron spectroscopy (HAXPES). We prepared ultrathin ferrite films using different oxygen partial pressures, showing pure metallic, light oxidic, and cobalt ferrite-like growth. Additional X-ray diffraction measurements confirm HAXPES results. [ABSTRACT FROM AUTHOR]

Ultrathin, transparent, and free‐standing films assembled from low‐dimensional nanomaterials (LDMs) are promising for various applications, including transparent heaters and membranes. However, the intact separation of the assembled films, especially those with controlled ultrathin thickness from deposited substrates, is a tremendous challenge, particularly for fast peeling off via self‐detaching. Herein, we propose a versatile method to rapidly peel off ultrathin assembled LDM films, including three types of carbon nanotubes, vermiculite, Ag nanowires, and carbon nanotube@graphene, by dissolving the MXene interlayer from the layer‐by‐layer filtered MXene/LDM Janus films using diluted H2O2. The MXene sacrificial interlayers play dual roles, including physical isolation of LDM films from filter membranes and the production of bubbles that buoy ultrathin LDM films, making them free‐standing. The integrality and self‐detaching rate of the LDM films are determined by the loading and reactivity of the MXene interlayers. The intact LDM films can self‐detach in 80 s by dissolving the optimized MXene interlayer and producing bubbles. The as‐made free‐standing ultrathin LDM films can be transferred to arbitrary substrates and exhibit outstanding performance as transparent heaters. This scalable method provides an efficient and versatile method to produce ultrathin, transparent, and free‐standing LDM films and finds new applications for the growing MXene family. [ABSTRACT FROM AUTHOR]

Smooth and uniform epitaxial ultrathin MgB2 films are desired for various electronic applications including hot-electron bolometers and single-photon detectors. However, the growth of ultrathin MgB2 films on SiC substrates using the Hybrid Physical-Chemical Vapor Deposition was dominated by the Volmer-Weber or island growth mode, which limited the minimum thickness for a conductive MgB2 film. Here we show the results of a study on the very early stage of the MgB2 film growth. We find that the root-mean-squared roughness and grain connectivity of ultrathin MgB2 films grown on C-terminated 6H-SiC($000\bar{1}$) substrate is much better than those on Si-terminated substrate. The result provides a simple solution to growing high-quality ultrathin MgB2 films for applications. [ABSTRACT FROM AUTHOR]

The morphology of the basal and overgrown lamellar crystals of PCL/PVME blends in ultrathin films are studied in detail. The blends were prepared from dilute solution with 60/40 composition ratios onto Si-substrate using the spin-coating method, melted above the equilibrium melt temperature, and subsequently crystallized at high temperatures. A truncated lozenge-shaped morphology of the crystals with stacks of lamellae layers (basal and overgrown lamellae) are observed by real-time atomic force microscopy. Depending on the crystallization conditions, the overgrown lamellae are found on-center and/or off-center on the basal lamellar crystal, correlated with the primary- or self-induced nucleation processes. During the crystallization process, the growth rate in the longitudinal direction is found double to the lateral direction. Electron diffraction (ED) pattern reveals these lamellae have very high crystallographic order; a characteristic similar to the single crystals. The overgrown lamellae have similar characteristics to the main basal lamellar crystal. Real-time AFM observation assisted with electron diffraction patterns shows a clear correlation the morphology and the nucleation process of the basal lamellar crystal and the overgrown lamellae of the blends. [ABSTRACT FROM AUTHOR]

Ultrathin oral films are novel delivery systems that do not require water to swallow, show rapid systemic release, and allow a comfortable and precise dosage. These films represent an option for administering active metabolites from medicinal plants used against insomnia, such as Agastache mexicana. However, incorporating complex bioactive molecules can compromise the functionality of the films. This study evaluated the physicochemical properties and biological activity of sodium alginate films added with the ethanolic extracts of Agastache Mexicana. After incorporating the extracts, the films preserved their homogeneous morphology, thickness (<50 µm), and solubility time (<10 min). In contrast, hardness increased more than 40%, and elasticity increased 60%. Infrared spectroscopy analysis revealed that, after the preparation of the films, the functional groups of the extracts and the chemical structure of the ultrathin films were maintained. Moreover, we demonstrated that the hypnotic effect of Agastache mexicana was preserved, since the sleep onset latency and total sleep time in a murine model were similar between the liquid extract and the film formulation. These data support the use of ultrathin films with natural extracts as a potential treatment for sleep disorders like insomnia. [ABSTRACT FROM AUTHOR]

Thermal camouflage has attracted increasing attention owing to the rapid development of infrared (IR) surveillance technologies. Various materials and systems have been developed to date, but the realization of high‐temperature thermal camouflage using ultrathin film/coating remains a great challenge; this is of great significance, especially for IR stealth in military equipment. This work demonstrates a series of ultrathin Ti3C2Tx MXene films (as low as 1 µm) with superior high‐temperature indoor/outdoor thermal camouflage performance: wide camouflage temperature range (from below −10 °C to over 500 °C), large reduction in radiation temperature (exceeding 300 °C for objects with temperatures over 500 °C), long‐term high‐temperature or fire stability, multifunctionality including disguised Joule heating capability, and high electromagnetic interference shielding efficiency. The superior high‐temperature thermal camouflage performance of the ultrathin MXene film is attributed to its low mid‐IR emissivity (0.19), which is comparable to that of stainless steel but far below that of other 2D nanomaterials, such as graphene. The multifunctional ultrathin MXene films prepared through simple vacuum‐assisted filtration provide a feasible method for efficient high‐temperature thermal camouflage using ultrathin films, demonstrating the great promise of MXene materials for thermal camouflage, IR stealth, counter‐surveillance, and security protection. [ABSTRACT FROM AUTHOR]

The formation of Ni nanoparticles for the growth of carbon nanotubes on a TiN barrier layer obtained by atomic layer deposition was studied. The interaction of the catalyst with the barrier layer is revealed. It consists of diffusion of Ni into TiN with activation energy of 0.75 eV. Assuming the melting of a nanosized Ni film, we simulated the formation of catalyst particles in terms of wetting transition theory. Comparison of simulation results and experimental data on catalyst particle formation allowed us to estimate effective interaction potential of Ni film and barrier layer. A change of the interaction potential due to variation of the film or barrier layer properties (e.g., material, structure, etc.) is responsible for change of the dynamics of catalyst particle formation including dynamics of their average size, number density and the shape of the size distribution function. [ABSTRACT FROM AUTHOR]

Graphdiyne (GDY) has been ideal candidate support for atomic catalysts (ACs) due to its unique conjugated two‐dimensional (2D) structure comprising both sp‐ and sp2‐hybrid carbon atoms. ACs/GDY can display excellent catalytic ability and high selectivity, emerging as a cutting‐edge research area in the past few years. Recently, a growing body of work has been done in ACs/GDY, ranging from screening appropriate combinations theoretically, continuous improvement to prepare few‐layered GDY to meet the critical challenge in this area, and successfully fabricating ACs/GDY in facile way. This Minireview briefly introduces recent advanced progress in this field, including the synthetic method for both thin GDY film and ACs/GDY, as well as theoretical analysis of different ACs/GDY systems, characterization, and applications. In the end, the challenges and further opportunities of ACs/GDY are summarized and proposed. It is hoped that this article brings new insights into the current study of ACs/GDY and promotes better development in this area. [ABSTRACT FROM AUTHOR]

This paper discusses the formation of the TiO x -SiO x nano-composite phase during annealing of ultrathin titanium oxide films (~27 nm). The amorphous titanium oxide films are deposited on silicon substrates by sputtering. These films are important for high-k dielectrics and sensing applications. Annealing of these films at 750 °C in the O 2 environment (for 15–60 min) resulted in the polycrystalline rutile phase. The films exhibit Raman peaks at 150 cm−1 (B 1g), 435 cm−1 (E g), and 615 cm−1 (A 1g) confirming the rutile phase. The signature TO (1078 cm−1) and LO (1259 cm−1) infrared active vibrational modes of Si– O –Si bond confirms the presence of silicon-oxide. The X-ray photoelectron spectra of the TiO x films show multiple peaks corresponding to Ti metal (453.8 eV); Ti4+ state (458.3 eV (Ti 2p 3/2) and 464 eV (Ti 2p 1/2)); and Ti3+ state (456.4 eV (Ti 2p 3/2) and 460.8 eV (Ti 2p 1/2)). The O1s XPS spectra peaks at 530–533 eV can be attributed to Ti–O and Si–O bonds of the TiO x -SiO x nano-composite phase in the annealed films. The depth profiling XPS study shows that the top surface of the annealed film is mainly TiO x and the amount of SiO x increases with the depth. [ABSTRACT FROM AUTHOR]

Conductive hydrogels show promising applications in wearable electronic devices. However, it is still challenging to increase the conductivity as well as the mechanical performance of the conductive hydrogels. In addition, it is more challenging to fabricate ultrathin conductive films with good mechanical strength and high transparency. In this study, a metal‐free flexible conductive hydrogel for flexible wearable strain sensor with high sensitivity is presented. The conductive hydrogel is prepared by polyvinyl alcohol (PVA) templated polymerizing of polypyrrole (PPy) followed by gelating based on the polymerizing and cross‐linking of polyacrylamide (PAAm). The conductive hydrogel is endowed excellent mechanical properties by multiple hydrogen bonds between the interpenetrating network of PVA, PPy, and PAAm. The tensile strength reaches up to 0.2 MPa at 500% and the compression strength reaches up to 1.5 MPa at 90%. It can withstand cyclic loads. The conductivity reaches 0.3 s m−1 and it is sensitive to stretching and compressing. Therefore, strain sensors are prepared based on such hydrogels to make wearable electronic devices, monitoring the subtle and large strains. It is worth noting that the composite material containing PVA has good film‐forming properties. Therefore, ultrathin conductive hydrogel films with high transparency (94.2%), high conductivity (7090 Ω/square) and large‐area are fabricated at low cost. [ABSTRACT FROM AUTHOR]

Currently, an urgent task related to creating a nuclear frequency standard is the identification of a low‐lying nuclear state in the thorium‐229 isotope. Herein, a method for measuring the single‐photon energy during the decay of an isomeric thorium‐229 nucleus implanted in a wide‐gap dielectric SiO2 (Eg = 9 eV) is developed. The proposed method utilizes thin silicon oxide layers obtained by thermal oxidization of the pure silica wafers, which allows measurement of the energy of photons in the ultraviolet (UV) range using an electronic spectrometer. The modeling study of electronic state excitation is provided via UV radiation from Kr, Xe, and D resonance discharging lamps. The obtained spectra are analyzed, and a method for determining the UV photon's energy is proposed. [ABSTRACT FROM AUTHOR]

Currently, an urgent task related to creating a nuclear frequency standard is the identification of a low‐lying nuclear state in the thorium‐229 isotope. Herein, a method for measuring the single‐photon energy during the decay of an isomeric thorium‐229 nucleus implanted in a wide‐gap dielectric SiO2 (Eg = 9 eV) is developed. The proposed method utilizes thin silicon oxide layers obtained by thermal oxidization of the pure silica wafers, which allows measurement of the energy of photons in the ultraviolet (UV) range using an electronic spectrometer. The modeling study of electronic state excitation is provided via UV radiation from Kr, Xe, and D resonance discharging lamps. The obtained spectra are analyzed, and a method for determining the UV photon's energy is proposed. [ABSTRACT FROM AUTHOR]

In order to pave the way for the formation of ultrathin electronically conductive organic films, we explored the structure and morphology of polythiophene derivatives in situ on the water surface. By changing the side chain end-group of poly(3-hexylthiophene) (P3HT) from methyl to carboxylic acid potassium salt, we showed that the film structure is drastically changed from a highly ordered bilayer to a short-range organized monolayer. Using a comprehensive experimental approach from macroscopic length scale to molecular organization as well as simulations of diffraction patterns, the detailed structure of the crystalline P3HT bilayer was determined. Some similarities with the structure measured on thicker films deposited on solid substrates were evidenced such as the π-stacking distance, the interlayer spacing, and the edge-on conformation. Some differences were also pointed out, in particular the in-plane packing along the polymer backbones and the shift of the upper monolayer with respect to the bottom one in this direction. Such observations highlighted the influence of both the forced two-dimensional confinement and the nature of the substrate (water) on the P3HT film structure. The presence of a carboxylic acid potassium salt at the end of the side chain induced completely different behavior. Indeed, high pressures were necessary to observe a π-stacking of the thiophene units, but only short-range, and although the polymer keeps a monolayer organization independently of the pressure, a deep change in the polymer conformation was evidenced with the pressure. [Display omitted] • Using an experimental approach from macroscopic to molecular length scale, the structure of P3HT bilayer is determined. • Changing the terminal group of the P3HT side chain to a polar group induces a radical change in the structure of the polymer. [ABSTRACT FROM AUTHOR]

We revisited the structure of monolayer iron nitride islands grown on Cu(001) using the well-established procedure, i.e. by bombarding the substrate with low-energy N+ ions, depositing Fe at room temperature and annealing in ultra-high vacuum (UHV). The geometric parameters of the obtained iron nitride were matching those of the "Fe 2 N" phase described in the literature and constituting the middle-plane-cut of the γ′-Fe 4 N unit cell. However, the atomic structure was found to exhibit an out-of-plane corrugation not reported by other authors so far. Moreover, the islands had an Fe 1.3 N stoichiometry and were characterized by a much higher work function value than the one predicted theoretically for the Fe 2 N phase. Based on these findings, we propose a new structural model for monolayer iron nitride on Cu(001), in which an additional N atom resides on top of every second Fe atom in each atomic row of the Fe 2 N. We also show that the Fe 1.33 N islands may be reduced to species with Fe 2 N stoichiometry through the exposure to O 2 at room temperature and subsequent annealing in UHV. Thus, direct formation of the Fe 2 N phase under specific experimental conditions, as indicated by other authors, may be also possible. • Ultrathin iron nitride islands were grown on Cu(001) using N+ sputtering, Fe deposition at RT and UHV annealing. • The structure and electronic properties of the obtained iron nitride did not fit the generally-accepted "Fe 2 N" model. • A new structural model including an additional N atom on every second Fe atom in each atomic row of Fe 2 N (leading to Fe 1.33 N stoichiometry) is proposed. [ABSTRACT FROM AUTHOR]

• Magnetic properties of sputter deposited [Pt/Co] multilayers were investigated. • The hysteresis of magnetization statics and dynamics were observed. • Hybrid in-plane and out-of-plane magnetization domains existence was deduced. • Experimental results are well described by micromagnetic simulations. The magnetic multilayer of Co separated by thin spacer layer of Pt was deposited by DC-magnetron sputtering. From the longitudinal magneto-optical Kerr effect based magnetometry and microscopy as well as magnetic force microscopy, the hybrid magnetization structure was deduced: the large size, micrometer scale magnetic domains with in-plane "core magnetization" patterned by nanometer scale domains with out-of-plane components. The hysteresis as a function of in-plane applied magnetic field of both: (i) magnetization curve measured by Superconducting Quantum Interference Device and (ii) dynamic responses measured by broadband Vector Network Analyzer spectroscopy were observed. The experimental results are well described by micromagnetic simulations. These magnetic history dependent effects were explained by magnetization cores, with in plane component, switching. [ABSTRACT FROM AUTHOR]

• Double wedges Pt/W(dW)/Co(dCo)/Pt and Pt/Co(dCo)/W(dW)/Pt were grown by MBE. • Magnetic coercivity strongly depends on dW for Pt/W/Co/Pt stacks. • Sharp dependence of Dzyaloshinskii-Morya interaction for dW < 0.5 nm. • Influence of dW on Co thickness of Spin Reorientation Transition was found. • Influence of dW on magnetic dead layer thickness was found. The results of magnetic investigations of epitaxial trilayers Pt/Co/Pt asymmetrically modified by inserting W layer at the bottom or top Co interfaces in the wide ranges of Co and W layer thicknesses are reported. The samples were epitaxially grown on Pt buffer in double wedge geometry: the d Co thickness gradient of the continuous Co wedge was orthogonal to the d W thickness gradient of non-magnetic W underlayer (overlayer) deposited either as step-like or continuous wedge. Resulting samples have Pt/W/Co/Pt (Pt/Co/W/Pt) stacking sequences. The influence of (d Co , d W) on static magnetization reversal processes were studied using magnetooptical Kerr effect; Brillouin light scattering (BLS) method was applied for dynamical characterization. The magnetic dead layer thickness d 0 abruptly increases until d W reaches ∼ 0.5 nm for both orderings. Then its value saturates for Pt/Co/W/Pt, while for Pt/W/Co/Pt samples a slow growth is observed. For d Co corresponding to out-of-plane magnetization the inserting of W layer leads to the strong reduction in coercivity (two orders of magnitude) and transition to in-plane magnetization in the case of Pt/W/Co/Pt ordering, while the Pt/Co/W/Pt samples demonstrates weak changes of coercivity with small change in magnetic anisotropy. The strength of interfacial Dzyaloshinskii-Moriya interaction (iDMI) and spin wave damping for selected d Co thicknesses as a function of d W were derived from BLS measurements. Inserting W with thickness d W ∼ 0.1 nm induces significant iDMI changes, iDMI saturates for d W > 0.4 nm. Our findings demonstrate the efficiency of thin W interlayer on modification of magnetic parameters in Pt/Co/Pt trilayer. [ABSTRACT FROM AUTHOR]

• The developed theory goes beyond previous methods and models. • The developed methodology develops an analytical solution for the Green's functions. • The results are in qualitative agreement with relevant experimental data. • The theory can be adapted for the dynamics of various excitations in binary alloys. • The analytic solutions represent considerable economies for numerical computations. We present the theory of a dynamic variant of the non-local coherent potential approximation (DNLCPA) to investigate the spin dynamics in ultrathin magnetic cobalt-gadolinium random alloy films Co 1 - c Gd c n , n atomic monolayers being their thickness. This novel theoretical approach in the classical spin wave representation introduces the idea for the scattering potential of a defect as an operator built up from the phase matching of the spin dynamics on the defect site with the spin dynamics in an otherwise virtual crystal. The scattering potentials are then used to establish a dynamic formulation of the CPA employing the Dyson's formalism. A mathematical approach is rigorously developed to solve analytically the Dyson T-matrix equation, and determine the unique physical solution for the configurationally averaged Green's function propagator of the disordered system. The DNLCPA numerical calculations for the Co 1 - c Gd c n systems yield the characteristic eigenmodes and energy dispersion curves of the confined spin wave excitations and their corresponding lifetimes, for arbitrary alloy concentration and diverse film thickness. Our theoretical results for the lifetimes of spin waves depend strongly on their wave vectors, and are in general agreement with recent experimental data. The developed DNLCPA theoretical method is general and can be applied to compute the spin dynamics for any magnetic random binary alloy nanostructure. [ABSTRACT FROM AUTHOR]

Abstract The effect of furnace annealing on the ferroelectricity and crystal phase of Hf 0.5 ZrO 2 (HZO) ultrathin films is studied as a function of film thickness. HZO films are deposited using atomic layer deposition (ALD) in a Ge-HZO-TiN stack with Pt as the top contact electrode. Furnace annealing is carried out after crystallizing the films with rapid thermal annealing in the presence of a TiN capping electrode. While furnace annealing did not have much impact on the 108 ALD cycles (~11 nm) film, it enhanced the ferroelectricity of the 44 ALD cycles film (~4.5 nm). Positive-up-negative-down tests provide evidence of ferroelectricity in the 40 ALD cycles (~4 nm) furnace annealed film after cycling the film at higher fields. Grazing incidence X-ray diffraction shows that the non-centrosymmetric orthorhombic phase responsible for ferroelectricity increased after furnace annealing in thinner films, but little change occurred in the 108 ALD cycles film that was rich in orthorhombic phase prior to furnace annealing. An analysis of the HZO films with a tapping mode atomic force microscope shows grain growth in the 44, and 40 ALD cycles films after furnace annealing. Highlights • Furnace annealing (FAn) improved the remnant polarization of a 4.5 nm film by 260%. • FAn improved the switched polarization (Psw) of a 4.5 nm film by 650%. • No positive effect of FAn on the ferroelectricity (FE) of a 11 nm film. • Positive-Up-Negative-Down tests confirm FE in a cycled 4 nm furnace annealed film. • FAn is an effective way to improve the FE of weakly ferroelectric films. [ABSTRACT FROM AUTHOR]

Abstract Complex mechanical behavior with phase transformation and high brittleness limits the reliability of silicon-based microelectromechanical systems. Although very hard ultra-thin films are being considered as protective overcoats to improve the service life of substrate materials, their resistance to fatigue can be at least as important as hardness when exposed to cyclic loading. In this study repetitive nano-impact tests with a spherical diamond probe have been used to investigate the fatigue behavior and protective role of 5 and 80 nm tetrahedral amorphous carbon (ta-C) films on silicon. At the lowest load there was delamination of the 80 nm film but not for the 5 nm film. At higher loads failure involved lateral cracking of the silicon substrate. Single impact tests showed that this was preceded by ring and radial cracking. Changing contact pressure during the test provided further support for the degradation mechanism and the influence of phase transformation in the Silicon substrate. Under repetitive contact the thin film systems showed lower impact depth and greater impact cycles before substrate fracture than the uncoated Silicon. This is related to their enhanced load support which affects phase transformation in the substrate, with potentially delamination providing an additional impact energy dissipation mechanism. Highlights • The fatigue behavior and protective role of ultrathin ta-C films on Si (100) have been investigated by nano-impact tests. • Impact fatigue mechanism has been investigated by a recently developed method for estimating the contact pressure. • The role of phase transformation of the Si substrate on the deformation process has been discussed. [ABSTRACT FROM AUTHOR]

Abstract Because of poor light absorption, Cu(In,Ga)Se 2 -based (CIGS) solar cells with an ultrathin absorber layer (<500 nm) require the development of reflective back contacts. To enhance rear reflectance in CIGS ultrathin devices, we investigate novel back contact architectures based on a silver metallic mirror covered with a thin layer of In 2 O 3 :Sn (ITO), which is fully compatible with nanopatterning for further light trapping improvements. First, numerical electromagnetic simulations of complete solar cells have been performed for a 490 nm thick CIGS absorber with various back contacts. We predict a short-circuit current density of J SC = 34.0 mA/cm2 for a 490 nm thick CIGS absorber with a silver nanostructured mirror. Second, we have fabricated and characterized 490 nm thick CIGS solar cells with transparent back contacts made of ITO, and reflective back contacts made of silver covered with ITO. Solar cells with a transparent ITO back contact exhibit an average efficiency of 10.0%, compared to 9.3% for standard molybdenum back contacts. A 5 nm thick Ga 2 O 3 layer is revealed at the ITO/CIGS interface by transmission electron microscopy and energy dispersive X-ray spectroscopy. When silver is added, the reflective back mirror leads to a J SC improvement of 4.6 mA/cm2 (from 22.4 to 27.0 mA/cm2). These results pave the way for efficient ultrathin CIGS solar cells on reflective back contacts. Highlights • Simulated absorption of ultrathin CIGS enhanced by a nanostructured back mirror. • ITO is a suitable back contact for ultrathin CIGS solar cells. • Experimental EQE of ultrathin CIGS devices improved with a reflective back contact. [ABSTRACT FROM AUTHOR]