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Herein, a large‐area nanofabrication process is proposed for flexible, ultrathin, and ultrasmooth gold films with extraordinary electro‐optical performance, making them competitive as transparent conductive electrodes (TCEs). The approach circumvents the thermodynamic constraints associated with the physical deposition of thin film electrodes, where 3D growth and metal dewetting delay stable percolation until the deposited film thickness exceeds 8–10 nm. It is demonstrated that a postgrowth ion irradiation procedure of compact gold films with Ar+ beam at very low energies, around 100 eV, predominantly induces ballistic smoothing and grain boundary restructuring. This process finally leads to the formation of ultrasmooth and ultrathin gold films that remain compact even at a thickness of 4 nm, with a sheet resistance in the range of 60 Ω sq−1 and an optical transparency around 80%. Remarkably, the films remain percolated even at thicknesses as low as 3 nm, with a transparency exceeding 90% and a sheet resistance of 190 Ω sq−1. These figures are comparable to those of commercial TCEs and enable simple, scalable, all‐metal transparent contacts on both rigid and flexible substrates, with significant potential for optoelectronic applications. [ABSTRACT FROM AUTHOR]

The development of ultrathin (≤5 nm) hafnia‐based ferroelectric (FE) films is essential for achieving low operating voltages, facilitating their integration into advanced process nodes for low‐power and non‐volatile memory applications. However, challenges in ultrathin FE films arise from the depolarization field and interface‐related issues, leading to an antiferroelectric‐like (AFE‐like) polarization switching behavior and more significant wake‐up effects, causing operational inconvenience and reliability concerns. Here, interface‐modulated ferroelectricity is reported in 4 nm Hf0.5Zr0.5O2 (HZO) thin films, demonstrating excellent properties with low operating voltage, enhanced switching speed, and high reliability. Electrical and structural characterizations reveal that adjusting interface asymmetry may introduce a substantial built‐in field (Ebi) and an AFE‐like switching behavior can exhibit a robust FE‐like characteristic. This AFE‐to‐FE‐like transition is driven by switching kinetics rather than commonly proposed phase transitions. Furthermore, a comprehensive model is developed to elucidate the intricate physics of the modulation mechanism by asymmetric interfaces, emphasizing the critical roles of depolarizing effects and Ebi on ferroelectricity. This work underscores the importance of interfaces in engineering ferroelectricity for advanced electronic applications. [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 σ s (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]

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]

Abstract The dimensionality of dynamic interfaces—domain walls (DWs) —is greatly influenced by symmetry and physical dimensions, irrespective of the microscopic details of the system. To address this fundamental question for the ferroelectric model system, the DW scaling criticality and dimensionality is investigated in ultrathin films of varied ferroelectric materials, compositions, and electrode–ferroelectric interfaces, grown on nominally flat and vicinal substrates. In spite of significant variations among ferroelectric systems, the observed prevalence of 1D DWs is consistent with a random bond disorder, elucidated through a scenario of 2D nucleation and growth‐driven DW creep. These findings highlight the thickness size‐dominated universal behavior of ferroelectric DWs, uncovering fascinating prospects for dimensionally engineered DW‐based nanoelectronics.

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]

Polycrystalline and epitaxial iron silicide (FeSi) films with thicknesses of 3.2–20.35 nm are grown on a Si(111) substrate using solid-phase and molecular-beam epitaxy at 350°C, as confirmed by X-ray diffraction data. Morphological studies reveal that the films grown by solid-phase epitaxy are continuous and smooth with a root-mean-square roughness ranging from 0.4 to 1.1 nm, while those grown by molecular-beam epitaxy exhibit increased roughness and consist of coalesced grains with sizes up to 1 μm and a pit density of up to 1 × 107 cm–2. In the case of solid-phase epitaxy, an increase in the thickness leads to incomplete silicide formation and the emergence of a layer of disordered iron silicide with a thickness ranging from 10 to 20 nm, possibly with an excess of iron. This is confirmed by a change in the nature of the temperature dependence of the resistivity ρ from semiconductor to semimetallic, which leads to a decrease in the resistivity by 1.5–2 times. The nonmonotonic character of the temperature dependence of the resistivity ρ(T) for an ultrathin FeSi film with a thickness of 3.2 nm is identified, exhibiting a maximum around 230–240 K, a rising segment from 160 to 65 K with Eg = 14.8 meV, and further unsaturated growth down to 1.5 K. As the thickness of the FeSi films grown by molecular-beam epitaxy increases, the minimum and maximum are not observed, but the nonmonotonic trend of ρ(T) with decreasing temperature and the opening of the band gap Eg = 23 meV are preserved. The possible reasons for the observed effects in the ρ(T) dependences are considered. An anomalous Hall effect is detected in ultrathin and thin FeSi films grown by solid-phase and molecular-beam epitaxy, respectively, which confirms the weak ferromagnetic properties of the films. The results demonstrate the feasibility of growing and controlling the properties of ultrathin and thin FeSi films on silicon using methods of solid-phase and molecular-beam epitaxy, providing them with unique transport and magnetic properties not present in single crystals. [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]

We have introduced a theory for the calculation of thermodynamic characteristics for some characteristic nanostructures (ultrathin films and superlattices), using the adapted method of two-time temperature Green's functions. In this paper, he has determined the coefficient of thermal conductivity using the definition of free energy and then compared their temperature dependence to the thermal conductivity behavior of the bulk structures. For the observed nanostructures, the thermal conductivity coefficient values are almost equal at low temperatures, but at the same time, significantly lower than the bulk sample values. That result could be useful for the possible achievement of better superconducting conditions in the observed compound nanostructures.

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]

We have introduced a theory for the calculation of thermodynamic characteristics for some characteristic nanostructures (ultrathin films and superlattices), using the adapted method of two-time temperature Green's functions. In this paper, he has determined the coefficient of thermal conductivity using the definition of free energy and then compared their temperature dependence to the thermal conductivity behavior of the bulk structures. For the observed nanostructures, the thermal conductivity coefficient values are almost equal at low temperatures, but at the same time, significantly lower than the bulk sample values. That result could be useful for the possible achievement of better superconducting conditions in the observed compound nanostructures. [ABSTRACT FROM AUTHOR]

In a previous report, 25 Å periodic metal–insulator transitions dependent on the thickness of CaRuO3 ultrathin films were discovered. Compared to the conventional size effect caused by quantum wells, the rate of change is a few billions of times greater at low temperatures. Although the electrical resistivity of insulating state differs by several orders with the film thickness, the enhancement trigger was not clarified. In this study, it is clarified that the magnitude of the extraordinary size effect varies with the element supply ratio owing to precise control of the molecular beam rates of calcium and ruthenium. The supplied calcium over ruthenium ratio Ca/Ru = 1.2–1.8 during CaRuO3 deposition results in a stoichiometric ratio of Ca:Ru = 1:1 on the CaRuO3 films. Calcium‐rich elemental supply conditions result in large electrical resistivity variations. Electrical resistivity oscillations with periods of T = 23.4 and 26.3 Å are observed for the growth conditions of Ca/Ru = 1.2 and 1.6, respectively. Furthermore, a flat surface with a roughness of ≈2 Å is required to observe the size effect. Thus, the insulation of an extraordinary size effect is enhanced in CaRuO3 ultrathin films grown under the condition of calcium‐rich Ca/Ru ≈ 1.6. [ABSTRACT FROM AUTHOR]

The D0 2 2 –Mn3Ga ferrimagnet promises potential applications in spintronics due to its low magnetization, strong perpendicular magnetic anisotropy and high Curie temperature. In the form of thin and thick films, these properties are preserved. Here, we report on the structural and magnetic characterization of epitaxial D0 2 2 –Mn 2. 6 Ga ultrathin films with thicknesses of 2 nm, 5 nm and 8 nm grown on Cr buffer layers by magnetron sputtering. We found that the films are perfect single crystals with flat surfaces and Curie temperatures higher than 300 K. The 2 nm-thick ultrathin film has higher magnetization than that of the thicker films, likely due to uncompensated ferrimagnetic planes, along the c-axis, linked to the surface roughness at the atomic scale. These properties highly suit the requirements for the elaboration of spintronic devices such as magnetic tunnel junctions. [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 Fe2+ cations are substituted by Ni2+ 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 In a previous report, 25 Å periodic metal–insulator transitions dependent on the thickness of CaRuO3 ultrathin films were discovered. Compared to the conventional size effect caused by quantum wells, the rate of change is a few billions of times greater at low temperatures. Although the electrical resistivity of insulating state differs by several orders with the film thickness, the enhancement trigger was not clarified. In this study, it is clarified that the magnitude of the extraordinary size effect varies with the element supply ratio owing to precise control of the molecular beam rates of calcium and ruthenium. The supplied calcium over ruthenium ratio Ca/Ru = 1.2–1.8 during CaRuO3 deposition results in a stoichiometric ratio of Ca:Ru = 1:1 on the CaRuO3 films. Calcium‐rich elemental supply conditions result in large electrical resistivity variations. Electrical resistivity oscillations with periods of T = 23.4 and 26.3 Å are observed for the growth conditions of Ca/Ru = 1.2 and 1.6, respectively. Furthermore, a flat surface with a roughness of ≈2 Å is required to observe the size effect. Thus, the insulation of an extraordinary size effect is enhanced in CaRuO3 ultrathin films grown under the condition of calcium‐rich Ca/Ru ≈ 1.6.

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]

In the approximation of the average spin method, a system of equations for determining the average magnetic moments of atoms at the interface between a ferromagnet and an antiferromagnet is formulated. It is possible to simulate the dependences of interfacial exchange interaction constant Ain on the temperature, antiferromagnetic layer thickness, and interface width by solving the system of equations for an ultrathin Ni/NiO film. It is found that the interfacial exchange interaction constant in a film with a fixed interface width at low temperatures increases with an increase in the thickness of the antiferromagnetic layer. With an increase in the interface width, the Ain value decreases by a factor of 1.3 and reaches its minimum level. [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]

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.

[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]

In many nano-(opto)-electronic devices, the roughness at surfaces and interfaces is of increasing importance, with roughness often contributing toward losses and defects, which can lead to device failure. Consequently, approaches that either limit roughness or smoothen surfaces are required to minimize surface roughness during fabrication. The atomic-scale processing techniques atomic layer deposition (ALD) and atomic layer etching (ALE) have experimentally been shown to smoothen surfaces, with the added benefit of offering uniform and conformal processing and precise thickness control. However, the mechanisms which drive smoothing during ALD and ALE have not been investigated in detail. In this work, smoothing of surfaces by ALD and ALE is studied using finite difference simulations that describe deposition/etching as a front propagating uniformly and perpendicular to the surface at every point. This uniform front propagation model was validated by performing ALD of amorphous Al2O3 using the TMA/O2 plasma. ALE from the TMA/SF6 plasma was also studied and resulted in faster smoothing than predicted by purely considering uniform front propagation. Correspondingly, it was found that for such an ALE process, a second mechanism contributes to the smoothing, hypothesized to be related to curvature-dependent surface fluorination. Individually, the atomic-scale processing techniques enable smoothing; however, ALD and ALE will need to be combined to achieve thin and smooth films, as is demonstrated and discussed in this work for multiple applications. [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]

A systematic study of the impact of film thickness on the properties of thin Bi films is presented. To this end, epitaxial films of high quality have been grown on a Si (111) substrate with thicknesses ranging from 1.9 to 29.9 nm. Broadband optical spectroscopy reveals a notable decline in the optical dielectric constant and the absorption peak height as the film thickness decreases, alongside a shift of the absorption maximum to higher photon energies. Raman and pump-probe spectroscopy show that the phonon mode frequencies increase upon decreasing film thickness, with the in-plane mode frequency rising by 10% from the thickest to the thinnest sample. The X-ray diffraction analysis reveals an increasing Peierls distortion for thinner films, explaining the observed property changes. Quantum chemical bonding analysis and density functional theory calculations show that the properties of thin bismuth are influenced by the interplay between electron localization and delocalization, characteristic of metavalently bonded solids. This study shows that for solids that utilize metavalent bonding, a thickness reduction leads to significant property changes. The effect can even be employed to tailor material properties without the need to change material stoichiometry., (© 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.)

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.

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]

• 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]

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]

In this work, simple and cost‐effective phyiscal vapor deposition method is applied for deposition of single Bi2Se3, Bi1.925Sn0.075Se3, Bi2Se2.975Te0.025 ultrathin films of average thickness 10–12 nm, and for the fabrication of n‐type 5‐layer nanolaminates. The nanolaminates are composed from alternating doped and undoped ultrathin films. Electrical and thermoelectric properties (Seebeck coefficient, resistivity, electron thermal conductivity, charge carrier concentration, and mobility) of nanolaminates as well as single ultrathin undoped and doped films are studied at room temperature under ambient conditions. Both types of nanolaminates show 75–125% increase of the Seebeck coefficient accompanied by the 65–85% reduction of the electron thermal conductivity in comparison with the nanostructured bulk materials of similar chemical compositions. The mechanisms underlying such improvement of properties of studied nanolaminates in comparison with the nanostructured bulk counterparts are discussed. [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]

Thin film semiconductor sensors based on palladium oxide were produced to analyse the concentration of ozone in the air. The palladium oxide films were obtained by means of thermal oxidation of ~ 20-30 nm metal in air at various temperatures. The oxide films were studied using electron microscopy and reflection high-energy electron diffraction. The optical, electrophysical, and gas sensitivity properties of the films were investigated. The study determined the optimal oxidation annealing temperature that ensures the uniform composition of the films and absence of electrical noise affecting the gas detection process. The article explains that electrical noise in ultrathin films is caused by their fragmentation during oxidation annealing. The study demonstrated the high sensitivity of the obtained films to oxide

The electronic structure of single-crystalline EuO (100) ultrathin films, together with their exchange splitting energy (ΔEEX) and ferromagnetic phase transition temperature (TC), was investigated by temperature- and thickness-dependent angle-resolved photoemission spectroscopy. Both ΔEEX and TC decreased monotonically with decreasing film thickness. The band shift showed an opposite thickness dependence at the Γ and X points, reflecting the balance of the hybridization between the Eu 4f and O 2p states (super-exchange interaction) and between the Eu 4f, O 2p, and Eu 5d states (indirect-exchange interaction). The observed transition from an indirect energy gap in the bulk to a direct gap in the ultrathin films of the ferromagnetic semiconductor EuO could be potential in future spintronic devices.

A significant challenge in quasi-two dimensional (2D) materials applications is the fabrication of large, suspended layers. This issue is particularly critical when the fabrication of closed cells is required, for example in in-operando x-ray photoemission spectroscopy (XPS) or transmission electron microscopy (TEM), or the design of Golay cell-like detectors. In the quasi-totality of working protocols, the 2D layer transfer is performed in a liquid environment, and the large surface tension forces that are developed during the drying steps often result in the layer damage. This effect becomes dramatic when the fabrication of sealed cells is required. Here we propose an alternative route that involves the sealing in a two-step process, with, first, the fabrication of a large and suspended membrane and then a sealing step performed with the help of a microfabricated self-aligned sealing cork. As a 2D suspended membrane, we choose an ultrathin membrane of single-layer Graphene coupled with a 7.5 nm thick film of evaporated titanium which was transferred over a large array of micrometric holes fabricated on a 30 μm thick silicon membrane. As a cork, we used a silicone structure obtained by pouring liquid silicone in a microfabricated silicon well. The throughput of the whole fabrication process was assessed either by electronic or optical microscopy, to obtain the total yield of integer cells, and by generating a pressure difference within each cell to test the sealing efficiency. A fabrication and sealing yield larger than 95% on arrays as large as 10 mm2 were demonstrated.