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Electrically induced resistive switching (RS) effects have been proposed as the basis for future non-volatile memories. In this work, 9 nm-thick BiFeO3 (BFO) epitaxial thin films were deposited on (001)-oriented SrTiO3 substrates by pulsed laser deposition and their resistive switching (RS) behaviors were investigated. A large resistive switching with ON/OFF ratio of ∼106 is observed, surpassing the performance of most resistive random access memories ever reported. The conducting filament is proposed to dominate the RS behavior in the positive voltage region, while the modulation of ferroelectric polarization is suggested to play a significant role in the negative voltage region. Our study significantly deepens the understanding of the physical origin of RS and could provide a reference for designing high-performance memories and memristors based on ultrathin ferroelectric films. [ABSTRACT FROM AUTHOR]

Epitaxial films of BiAl x Fe 1 − x O 3 (xBAFO) were grown on SrTiO 3 (STO) and SrRuO 3 buffered STO substrates using pulsed laser deposition. To understand the effects of Al substitution at the Fe-site of BFO, we systematically investigated its impact on the material's crystal structure, surface morphology, ferroelectric properties, and magnetic properties. Our x-ray diffraction analysis revealed that phase-pure xBAFO films can be stabilized for Al concentrations between 0% and 35%, without the formation of secondary phases, due to the isotypic crystal structures of BiAlO 3 and BiFeO 3. This allowed the rhombohedral structure of BAFO to be preserved. We then characterized the ferroelectric properties of xBAFO (0 ≤ x ≤ 0.25) by analyzing polarization-voltage hysteresis loops, which exhibited a transition from a nearly square shape to a more slanted shape with increasing Al substitution. Additionally, piezoresponse force microscopy revealed that the domain growth mode, shape, size, dimension, and nucleation play a crucial role in the switching behavior of ferroelectric materials. Furthermore, we observed a modest enhancement in magnetization due to the modified spin ordering of Fe atoms with Al substitution. Notably, the optimal ferroelectric and magnetic properties were achieved at an Al concentration of 15%. These findings suggest that BAFO is a promising magnetoelectric material with desired functionalities for realizing BFO-based next-generation non-volatile memory devices. [ABSTRACT FROM AUTHOR]

Additive manufacturing has the potential to repair high value components, saving significant time and resources; however, the level of reliability and performance of additive repairs is still relatively unknown. In this work, the structure–property and performance of laser wire additive manufacturing repairs in 1100 aluminum are investigated. Two types of intentional damage are inflicted on the samples and subsequently repaired with pulsed laser deposition additive manufacturing. Quasi-static (10 − 3 s − 1 ) and high strain-rate (10 − 3 s − 1 ) mechanical testing is carried out with in situ diagnostics and post-mortem imaging. The results show that while the quasi-static strength and ductility of samples with a repaired region are lower than a pristine sample, the dynamic strength under shock loading is comparable. This work highlights both the potential utility of additive manufacturing for repair purposes, the significant risk of compromised performance of additive parts under specific conditions, and the need to test at varying strain rates to fully characterize material performance. [ABSTRACT FROM AUTHOR]

We investigate the stability of the polar surface of ZnO films grown homoepitaxially on atomically flat ZnO (000 1 ¯) O-face substrates by neodymium yttrium aluminum garnet (Nd:YAG) pulsed laser deposition (PLD). For films grown in the temperature range from 500 to 700 °C, ion scattering spectroscopy showed that the film surface termination was the same as the ZnO substrate. Even for a Mg0.2Zn0.8O/ZnO superlattice, no polarity reversal occurred, indicating that the ZnO (000 1 ¯) O-face is highly stable, despite the film surface sputtering caused by the high kinetic energy of the PLD plume generated by the Nd:YAG laser. [ABSTRACT FROM AUTHOR]

Pristine and dysprosium-doped ZnO thin films, highly c-axis oriented, were grown on a c-Al2O3 substrate using the pulsed laser deposition technique. During the deposition process, the growth was impacted by changes in the oxygen partial pressure. The structural, optical, and compositional properties of the pristine and dysprosium-doped ZnO thin films were systematically characterized using various state-of-the-art experimental techniques. The crystallinity associated with these films was observed to be highly dependent on the oxygen partial pressure maintained during the growth process. An average optical transparency of more than ∼90% in the visible spectral range (i.e., 400–800 nm) was observed for all specimens. For doped specimens, expected intra-4fn emissions of (dysprosium) Dy3+ ions that emanated from the 4F9/2 energy state were observed in room-temperature photoluminescence spectra under direct excitation. The Jacobian-transformed wavelength-to-energy plot for Dy-doped ZnO thin films in the UV-Visible region revealed intriguing findings. Specifically, it depicted a prominent peak at 2.82 eV, indicative of the energy state of Dy3+ ions, alongside intense band-edge emission and various defect-related emissions. The intensity of these transitions was observed to depend on the oxygen partial pressure kept during deposition. An x-ray photoelectron spectroscopy analysis of the doped specimen confirmed the +3 oxidation state of dysprosium into the ZnO matrix. These results provide a promising approach for controlling the doping and growth strategy of Dy-doped ZnO thin films, thereby opening up a wide range of applications and enhancement for next-generation optoelectronic devices. [ABSTRACT FROM AUTHOR]

Ferroelectric properties of hafnium-based thin films have gained significant interest, yet the fundamental mechanisms responsible for the emergence of the ferroelectric phase continue to be inadequately investigated. In contrast with polycrystalline films fabricated by atomic layer deposition or sputter methods, which possess uncertainty in polarization orientation, epitaxial ferroelectric HfO2-based materials are less investigated, especially for factors such as electric field and oxygen vacancy, which are proposed and examined for their potential impacts on phase stability. In this study, Y-doped hafnium oxide (HYO) ferroelectric epitaxial films were fabricated using pulsed laser deposition, with variations in oxygen pressure during the deposition process. Structural and electrical analyses of HYO epitaxial ferroelectric films prepared under differing oxygen pressures revealed a correlation between the ferroelectric properties of the films and the oxygen content. An optimal selection of oxygen pressure was found to be conducive to the formation of HYO epitaxial ferroelectric films, presenting a promising avenue for future ferroelectric memory applications. [ABSTRACT FROM AUTHOR]

Ferroelectric properties of hafnium-based thin films have gained significant interest, yet the fundamental mechanisms responsible for the emergence of the ferroelectric phase continue to be inadequately investigated. In contrast with polycrystalline films fabricated by atomic layer deposition or sputter methods, which possess uncertainty in polarization orientation, epitaxial ferroelectric HfO2-based materials are less investigated, especially for factors such as electric field and oxygen vacancy, which are proposed and examined for their potential impacts on phase stability. In this study, Y-doped hafnium oxide (HYO) ferroelectric epitaxial films were fabricated using pulsed laser deposition, with variations in oxygen pressure during the deposition process. Structural and electrical analyses of HYO epitaxial ferroelectric films prepared under differing oxygen pressures revealed a correlation between the ferroelectric properties of the films and the oxygen content. An optimal selection of oxygen pressure was found to be conducive to the formation of HYO epitaxial ferroelectric films, presenting a promising avenue for future ferroelectric memory applications. [ABSTRACT FROM AUTHOR]

We have investigated the He buffer gas process of moderating the kinetic energy of the pulsed laser deposition (PLD) plume during EuxY2−xO3 phosphor film growth. When using a neodymium yttrium aluminum garnet laser for PLD thin film growth, the kinetic energy of the ablation plumes can be high enough to cause the formation of point defects in the film. The buffer gas pressure is an important process parameter in PLD film growth. We find that the presence of the He buffer gas reduces the kinetic energy of the laser deposition plume through many low-angle collisions in the gas phase by a factor of 7 without reducing the deposition rate. This is because He is much lighter than any of the elements in the plume and it does not affect the composition of the oxide films. Consequently, the resputtering of the Y2O3 film surface by the plume was significantly suppressed in the presence of the He gas moderator, leading to a decrease of the defect density in the Y2O3 films. The improvement of the film quality was verified by a systematic analysis of time-resolved photoluminescence (PL) data for EuxY2−xO3 composition–gradient films. The PL lifetime and intensity of Eu0.2Y1.8O3, which shows the highest PL intensity, increased by 13.3% and 36.4%, respectively, when the He gas moderation process was used. The He buffer gas process is applicable to the PLD growth of the other oxide materials as well, where the reduction of the kinetic energy of the plume would bring the PLD process closer to the molecular beam epitaxy growth condition. [ABSTRACT FROM AUTHOR]

Layered thin films of the ferroelectric perovskite Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZT) and the ferromagnetic half-metal La0.80Sr0.20MnO3 (LSMO) are well-known multiferroic systems that show promise for spintronic applications. In this work, the structure–property relationships are explored in novel BCZT/LSMO thin film heterostructures with optimized ferroic properties. Epitaxial BCZT/LSMO thin film heterostructures are grown by varying the lattice mismatch strains on single crystal LaAlO3 (LAO) (100) and MgO (100) substrates using the pulsed laser deposition technique. The epitaxial strain in the films gives rise to a tetragonal distortion of the BCZT and LSMO unit cells and significantly affects their magnetotransport and magnetodielectric properties. The BCZT/LSMO/LAO heterostructure exhibits a colossal magnetoresistance effect due to a large out-of-plane tensile strain, which induces enhanced carrier hopping in the LSMO layer as compared to the BCZT/LSMO/MgO film. The larger tetragonal distortion of the BCZT unit cell in BCZT/LSMO/MgO contributes to higher dielectric permittivity, with a greater dielectric maxima temperature and freezing temperature. Magnetodielectric measurements reveal a hitherto unobserved giant magnetodielectric effect in the BCZT/LSMO/MgO film, attributed to a large in-plane strain, which induces interfacial polarization distortion at the interfacial layer. Overall, this work elucidates the unique strain and charge-mediated cross-coupled phenomena of magnetic and electric orders in multiferroic thin film heterostructures, which are critical for their technological applications. [ABSTRACT FROM AUTHOR]

Plasmonic catalysis triggers the dissociation of H 2 or adsorbed O 2 (sluggish processes) under continuous wave excitation via plasmon decay. This is coupled to interband or intraband excitation of d-band or sp-band, respectively, to levels above fermi level of metals. Here, we have studied the plasmonic and photocatalytic behavior in an environment friendly medium with AM 1.5 G sunlight of CuO/ Cu 2 O thin films fabricated by pulsed laser deposition technique in vacuum with varying thickness. We have achieved ∼ 0.59 kmol h − 1 g − 1 H 2 production in the CuO/ Cu 2 O film with a thickness of ∼ 27 nm. The role of plasmons with metal–dielectric and semiconductor–semiconductor interfaces is conducted through both experimental and theoretical approaches. The results suggest that the impact of plasmonic catalysis/synthesis is subject to the dimension, composition, and band alignment of two interface materials. [ABSTRACT FROM AUTHOR]

We have fabricated the ZnFe2O4/ZnO (ZFO/ZnO) heterostructure on a silicon substrate by pulsed laser deposition technique and studied the magnetization switching by the electric field in the ZFO/ZnO heterostructure using an indigenously developed optical cantilever beam magnetometer setup. The magnetization (M) vs electric field (E) curve reveals that the magnetization of the ZFO film has been switched by an electric field applied along the thickness of the ZnO film. The saturation magnetization is found to be 28.77 MA/m from the M–E curve. The emergence of electric field-driven magnetization switching in the ZFO/ZnO heterostructure is attributed to the strain-mediated magnetoelectric coupling between the electric polarization of the ZnO film and the magnetization of the ZFO film as evidenced by the butterfly-type hysteresis behavior of magnetization with the applied electric field. However, the realization of electric field-controlled magnetization switching in the ZFO/ZnO heterostructure is regarded as a potential aspect for the fabrication of energy-efficient spintronic devices such as magnetoelectric random access memory cells, highly sensitive magnetic field sensors, magneto-logic devices, and neuromorphic devices. [ABSTRACT FROM AUTHOR]

This study explores the feasibility of precisely tuning the resistive switching behavior of Au/BiFeO 3 /Pt/Ti/SiO 2 /Si memristors through controlled modulation of laser energy density during pulsed laser deposition (PLD). By systematically reducing the laser energy density within the fabrication process, notable alterations in the properties of the BiFeO 3 (BFO) thin film are observed. As the laser energy density decreases, the grain size in the BFO film and the thickness of the film decrease. Furthermore, we obtain the minute structural variations in response to the diverse laser energy densities employed during the deposition process. Energy-dispersive x-ray spectroscopy analysis is employed to investigate the distribution of Ti 4 + ions within the BFO thin film. The reduction in the grain size and film thickness, along with the prominent nucleation of specifically oriented grains, and the diffusion of Ti 4 + ions, lead to the BFO memristor fabricated with a lower laser energy density having more grain boundaries and a shortened conduction path (grain boundary) in the thickness direction. Consequently, the enhanced movement of oxygen vacancies facilitates their preferential accumulation along the grain boundaries within the BFO layer, resulting in an augmented on/off ratio, rectification factor, and set current in the devices. Overall, our findings explain the significant influence of laser energy density in PLD on the microstructure and electrical properties of BFO thin films. Particularly, the lower energy densities are employed to improve electrical characteristics. This research not only enhances our fundamental understanding but also provides valuable insights into optimizing BFO memristors for reliable, robust, and practical applications. [ABSTRACT FROM AUTHOR]

We have grown and characterized (110)-oriented YBa2Cu3O7−x (YBCO)/PrBa2(Cu0.8Ga0.2)3O7−x (PBCGO) bilayer and YBCO/PBCGO/YBCO trilayer heterostructures, which were deposited by pulsed laser deposition technique for the nanofabrication of (110)-oriented YBCO-based superconductor (S)/insulator (I)/superconductor (S) tunneling vertical geometry Josephson junction and other superconductor electronic devices. The structural properties of these heterostructures, investigated through various x-ray diffraction techniques (profile, x-ray reflectivity, pole figure, and reciprocal mapping), showed (110)-oriented epitaxial growth with a preferred c-axis-in-plane direction for all layers of the heterostructures. The atomic force microscopy measurement on the top surface of the heterostructures showed crack-free and pinhole-free, compact surface morphology with about a few nanometer root mean square roughness over the 5 × 5 μm2 region. The electrical resistivity measurements on the (110)-direction of the heterostructures showed superconducting critical temperature (Tc) values above 77 K and a very small proximity effect due to the interfacial contact of the superconducting YBCO layers with the PBCGO insulating layer. Raman spectroscopy measurements on the heterostructures showed the softening of the Ag-type Raman modes associated with the apical oxygen O(4) and O(2)-O(3)-in-phase vibrations compared to the stand-alone (110)-oriented PBCGO due to the residual stress and additional two Raman modes at ∼600 and ∼285 cm−1 frequencies due to the disorder at the Cu–O chain site of the PBCGO. The growth process and structural, electrical transport, and Raman spectroscopy characterization of (110)-oriented YBCO/PBCGO bilayer and YBCO/PBCGO/YBCO trilayer heterostructures are discussed in detail. [ABSTRACT FROM AUTHOR]

Ultrawide bandgap ZnGa2O4 (ZGO) thin films were grown on sapphire (0001) substrates at various growth temperatures with a perspective to investigate the electrical and optical characteristics required for high-power electronic applications. Due to the variation in the vapor pressure of Zn and Ga, severe loss of Zn was observed during pulsed laser deposition, which was solved by using a zinc-rich Zn0.98Ga0.02O target. A pure phase single-crystalline ZGO thin film was obtained at a deposition temperature of 750 °C and an oxygen pressure of 1 × 10−2 Torr. The out-of-plane epitaxial relationship between the sapphire and ZGO thin film was obtained from φ-scan. The x-ray rocking curve of the ZGO thin film grown at 750 °C exhibits a full width at half maximum of ∼0.098°, which indicates a good crystalline phase and quality of the thin film. Core-level x-ray photoelectron spectroscopy of ZGO grown at 750 °C indicated that Zn and Ga were in the 2+ and 3+ oxidation states, respectively, and the atomic ratio of Zn/Ga was estimated to be ∼0.48 from the fitted values of Zn-2p3/2 and Ga-2p3/2. The high-resolution transmission electron microscopy images revealed a sharp interface with the thickness of the ZGO film of ∼265 nm, and the signature of minor secondary phases was observed. The bandgap of the ZGO film at different growth temperatures was calculated from the ultraviolet-diffuse reflectance spectroscopy spectra, and its value was obtained to be ∼5.08 eV for the 750 °C grown sample. The refractive index (n) and the extinction coefficient (k) were determined to be ∼1.94 and 0.023 from the ellipsometric data, respectively, and the real dielectric function (ɛr) was estimated to be ∼6.8 at energy 5 eV. The ultrawide bandgap and dielectric function of ZGO recommend its possible potential applications in deep-ultraviolet optoelectronic devices and high-power electronics. [ABSTRACT FROM AUTHOR]

The antiferromagnetic orthoferrite YFeO3 possesses fascinating magnetic properties for spintronics, such as terahertz spin dynamics, ultrafast domain wall motion, and long magnon decay length. YFeO3 belongs to a special family of antiferromagnets that show an unusually strong non-trivial Kerr response due to its weak ferromagnetism. The highly stable antiferromagnetic domains without any spontaneous spin rotation transitions below the 645 K Néel temperature may be useful for nanoscale device applications. We report the successful fabrication of high-quality twinning-free (110)-oriented YFeO3 films by pulsed laser deposition. Detailed structural and magnetic characterization revealed that the crystal structure and magnetic properties of the YFeO3 films are comparable to bulk single crystals. We show that the spin rotation under high magnetic fields follows the two-sublattice approximation model. The film surface is atomically flat with step-terrace surface morphology. A longitudinal magneto-optic Kerr (MOKE) rotation of 10 mdeg was observed at room temperature, which is consistent with earlier reports on bulk single crystals. The in-plane anisotropy of the Kerr response corresponds to the obtained magnetic anisotropy from the SQUID measurement. The large MOKE signal enables the imaging of antiferromagnetic domains and their reversal. The domain size was found to be larger than 100 μm. These high-quality YFeO3 thin films facilitate the fabrication of antiferromagnetic spintronic devices and provide a convenient platform for studying various spin-related phenomena in thin films and at interfaces. [ABSTRACT FROM AUTHOR]

Functional thin films of nanoscale metal pillars in oxide or nitride matrices known as vertically aligned nanocomposite (VAN) have gained much interest owing to their unique strain-coupled and highly anisotropic properties. So far, the deposition of these films has been explored mostly experimentally. In this work, a density functional theory (DFT)-based kinetic Monte Carlo simulation model using Bortz–Kalos–Lebowitz algorithm was developed to understand the growth of VAN films deposited by pulsed laser technique on mismatching substrates. The model has been parameterized and applied to understand the kinetics of growth thin films consisting of Au pillars in CeO2 matrix deposited on SrTiO3 substrates. The effects of pulsed laser deposition (PLD) conditions including the pulse frequency, deposition flux, and substrate temperature were explored. The simulations indicate that the Au pillar size and shape exhibit significant dependence on the PLD conditions. Namely, increasing the temperature increases the average pillar size and lowers the pillar density, and vice versa. In addition, the simulations revealed that increasing the deposition rate results in lowering the average pillar size and increasing the density. Particularly, the DFT results suggest that Au pillar size can be tuned during the initial growth of the first monolayer due to the significantly low activation barrier. Our analysis showed that the relationship between the average pillar size and pillar density is influenced by the kinetics. Furthermore, autocorrelation analysis showed that pillars self-organize in quasi-ordered patterns at certain windows of the deposition conditions, which is attributed to the complex nature of the chemical interactions in the system, the kinetics, and the deposition parameters. [ABSTRACT FROM AUTHOR]

In the present paper, we apply a blind fitting algorithm to model two-dimensional energy-incidence angle maps of soft x-ray resonant reflectivity measured in nanoscale epitaxial multilayers of multiferroic ε-Fe2O3 grown by pulsed laser deposition. The possibility of fitting the spectral shape of the complex refraction index across the Fe L3 absorption edge without having an initial guess about the optical constants has been demonstrated. The spectral shape fitting of the real (f1) and imaginary (f2) parts of the atomic scattering factor has been carried out by using a specially designed software utilizing OpenCL fast calculations on graphical processing units. The Kramers-Kronig relations between f1 and f2 are automatically taken into account by the fitting algorithm. A reasonable agreement between blindly generated and reference scattering factor spectra derived independently from an x-ray absorption spectroscopy experiment has been demonstrated. The blind fitting has been compared with the alternative refinement routines, in which small free variations of the reference spectral shapes (or no variations at all) have been allowed. The presented approach to the resonant x-ray reflectometry modeling makes it unnecessary to acquire the optical constant spectral shapes in advance and, thus, is especially helpful when such spectra cannot be physically measured, e.g., for a buried layer of a multilayer system. [ABSTRACT FROM AUTHOR]

Bi1−xBaxFeO3 (BBFO, x = 0, 0.03, 0.1) thin films were epitaxially grown on SrRuO3-buffered SrTiO3 (001) substrates by pulsed laser deposition. With increasing Ba content, the BBFO thin films show significantly reduced leakage currents but suppressed ferroelectric polarization. X-ray diffraction reciprocal space mappings and Raman spectra indicate a structural evolution from a rhombohedral-like to tetragonal-like phase in the BBFO thin films. Optical absorption and photoelectron spectroscopy measurements demonstrate a modulation of energy band structures in the BBFO thin films. With A-site Ba acceptor doping, the BBFO thin films exhibit a blue-shift of optical bandgap and an increase in work function. The energy positions of conduction and valence bands of the BBFO thin films have been modulated, and the Fermi level shifts down to the center of the forbidden band, but acceptor-doped BFO thin films still show n-type conduction. The presence of extra oxygen vacancies by acceptor doping is supposed to make contribution to conduction behavior. This study provides a method to manipulate the functional properties and gives insights into the physics of Ba doping in BFO thin films. [ABSTRACT FROM AUTHOR]

The discovery of strontium niobate (SNO) as a potentially new transparent electrode has generated much interest due to its implications in various optoelectronic devices. Pristine SNO exhibits exceptionally low resistivity (∼10−4 Ω cm) at room temperature. However, this low resistivity occurs due to large number of carrier concentration in the system, which significantly affects its optical transparency (∼40%) in the visible range and hinders its practical applications as a transparent electrode. Here, we show that modulating the growth kinetics via oxygen manipulation is a feasible approach to achieve the desired optoelectronic properties. In particular, epitaxial (001) SNO thin films are grown on (001) lanthanum aluminate by pulsed laser deposition at different oxygen partial pressures and are shown to improve the optical transparency from 40% to 72% (λ = 550 nm) at a marginal cost of electrical resistivity from 2.8 to 8.1 × 10−4 Ω cm. These changes are directly linked with the multi-valence Nb-states, as evidenced by x-ray photoelectron spectroscopy. Furthermore, the defect-engineered SNO films exhibit multiple electronic phases that include pure metallic, coexisting metal-semiconducting-like, and pure semiconducting-like phases as evidenced by low-temperature electrical transport measurements. The intriguing metal-semiconducting coexisting phase is thoroughly analyzed using both perpendicular and angle-dependent magnetoresistance measurements, further supported by a density functional theory-based first-principles study and the observed feature is explained by the quantum correction to the conductivity. Overall, this study shows an exciting avenue for altering the optical and transport properties of SNO epitaxial thin films for their practical use as a next-generation transparent electrode. [ABSTRACT FROM AUTHOR]

We employ analytical transmission electron microscopy (TEM) to correlate the structural and chemical environment variations within a stacked epitaxial thin film of the high entropy oxide (HEO) Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O (J14), with two layers grown at different substrate temperatures (500 and 200 °C) using pulsed laser deposition (PLD). Electron diffraction and atomically resolved STEM imaging reveal the difference in out-of-plane lattice parameters in the stacked thin film, which is further quantified on a larger scale using four-dimensional STEM (4D-STEM). In the layer deposited at a lower temperature, electron energy loss spectroscopy (EELS) mapping indicates drastic changes in the oxidation states and bonding environment for Co ions, and energy-dispersive X-ray spectroscopy (EDX) mapping detects more significant cation deficiency. Ab initio density functional theory (DFT) calculations validate that vacancies on the cation sublattice of J14 result in significant electronic and structural changes. The experimental and computational analyses indicate that low temperatures during film growth result in cation deficiency, an altered chemical environment, and reduced lattice parameters while maintaining a single phase. Our results demonstrate that the complex correlation of configurational entropy, kinetics, and thermodynamics can be utilized for accessing a range of metastable configurations in HEO materials without altering cation proportions, enabling further engineering of functional properties of HEO materials.

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

Transition metal oxides provide opportunities to induce and modulate the superconducting state, due to the delicate interplay between charge, spin, orbital, and lattice order. In this work, 5d transition metal oxide SrTaO3 films were deposited by pulsed laser deposition, and an anomalous negative resistance was observed. The negative resistance can be ascribed to the nonuniform conductivity, associated with nonuniform electronic states in the SrTaO3 thin films, as confirmed by conductive atomic force microscopy and x-ray photoelectron spectroscopy. Moreover, a sharp drop in the resistance together with a decrease in magnetization was observed at around 40 K. This might imply a possible superconducting state. The negative resistance can be well explained based on an equivalent circuit comprising normal and superconductive states, also supporting the possible superconducting state in SrTaO3 thin films. This work promotes the exploring and revealing of the mechanism in tantalates superconductivity. [ABSTRACT FROM AUTHOR]

The increasing demand for functional nanodevices in sustainable energy applications necessitates the development of innovative approaches. In this study, we present the fabrication and characterization of three-dimensional (3D) structures coated with titanium dioxide (TiO 2) nanorods (NRs). These novel devices are created through the integration of four distinct techniques, multi-photon lithography, post-thermal treatment, pulsed laser deposition, and an aqueous chemical growth, enabling their unique properties and functionalities in photocatalysis. The photocatalytic performance of the 3D devices is evaluated through the degradation of organic pollutants, such as methylene blue and stearic acid, showcasing their efficiency in reducing pollutant concentrations. The devices demonstrate a remarkable decomposition coefficient (k = 0.059 min − 1 ), highlighting their enhanced photocatalytic efficiency. Additionally, we propose a rapid fabrication technique using 3D holographic printing to create large-area TiO 2 -coated micro-structured photocatalytic devices at the mesoscale regime. This approach increases the active surface area, further enhancing the devices' photocatalytic capabilities. By combining additive micro-manufacturing, TiO 2 NR coating, and holographic printing, our work introduces a promising avenue for the development of advanced nanodevices with superior photocatalytic performance in sustainable energy applications. [ABSTRACT FROM AUTHOR]

We investigated leakage current characteristics affected by crystallinity and domain wall currents of epitaxial Bi5Ti3FeO15 (BTFO) thin films on Nb-doped SrTiO3 substrates. Highly a-oriented BTFO thin films, highly c-oriented BTFO thin films, and BTFO thin films with a mixture of a-oriented and c-oriented crystallinity were prepared by controlling the substrate temperature and the pulsed laser deposition deposition rate. Highly c-oriented BTFO thin films exhibited the best leakage current characteristics because the Bi2O2 layers were placed perpendicular to the c-axis to reduce leakage currents. The BTFO thin films with a mixture of a-oriented and c-oriented crystallinity showed larger leakage currents compared to highly c-oriented BTFO thin films. The current domains of the BTFO thin films corresponding to the ferroelectric domain structures were observed by a conducting atomic force microscope, and it was observed that leakage currents were formed around the domain walls. In particular, the largest leakage currents are formed at the boundaries of c-oriented domains and a-oriented domains, and these domain boundaries confirmed that the BTFO thin films with a mixture of a-oriented and c-oriented crystallinity were responsible for the largest leakage currents. [ABSTRACT FROM AUTHOR]

In this work, the applicability of pulsed laser deposition (PLD) of transparent conductive oxides (TCOs) on high-quality ultra-thin poly-Si based passivating contacts is explored. Parasitic absorption caused by poly-Si layers can be minimized by reducing the poly-Si layer thickness. However, TCO deposition on poly-Si contacts, commonly by sputtering, results in severe deposition-induced damage and further aggravates the surface passivation for thinner poly-Si layers (<20 nm). Although a thermal treatment at elevated temperature (∼350 °C) can be used to partially repair the surface passivation quality, the contact resistivity severely increases due to the formation of a parasitic oxide layer at the poly-Si/ITO interface. Alternatively, we show that PLD TCOs can be used to mitigate the damage on ultra-thin (∼10 nm) poly-Si layers. Further improvement in poly-Si contact passivation can be achieved by increasing the deposition pressure while low contact resistivities (∼45 mΩ cm2) and good thermal stability (up to 350 °C) are achieved with a PLD indium-doped tin oxide (ITO) layer on high-quality ultra-thin poly-Si(n+) contacts. This allows for the application of a highly transparent front side contact by combining the excellent opto-electrical properties of a PLD ITO film with a 10 nm thin poly-Si contact. [ABSTRACT FROM AUTHOR]

Realizing an oxide thin film with proper stoichiometry is one of the most challenging objects in materials science. Owing to the growth dynamics as well as kinetics, the physical properties of thin films often differ from their bulk counterparts. Here, we report pulsed laser-deposited thin films of LaBO3 (B = Mn, Fe, Co) grown on a SrTiO3 (001) substrate under various thermodynamic conditions. Structural, magnetic, and optical studies have been carried out. The x-ray diffraction study confirms that an appropriate choice of growth thermodynamics may help one to realize epitaxially grown films on the SrTiO3 substrate with out-of-plane lattice parameters 3.976, 3.984, and 3.825 Å for LaMnO3 (LMO), LaFeO3 (LFO), and LaCoO3 (LCO), respectively. A mixed valence state of Mn2+, 3+, 4+ for LMO, a Fe3+ state for LFO, and a mixed state of Co2+, 3+ for LCO have been confirmed by x-ray photoelectron spectroscopy, which is in good agreement with the Ellingham diagram. The optical study showed a bandgap of 1.2, 2.5, and 1.5 eV for LMO, LFO, and LCO, respectively. Ultraviolet photoelectron spectroscopy (UPS) shows a glimpse of the valence band maximum and Fermi level position. UV, UPS, and photoconductive study simultaneously results in a type II band bending, i.e., staggered type bending is observed at these interfaces. Room temperature weak ferromagnetism along with the insulating nature and a sign of photovoltaic application of these thin films fascinate to carry forward rigorous study from fundamental as well as technological points of view. [ABSTRACT FROM AUTHOR]

A polycrystalline ZnO film is grown on a silicon substrate by the pulsed laser deposition method, and the electric field-induced magnetization in ZnO using an optical cantilever beam magnetometer setup is studied. The magnetization vs bipolar dc electric field measurements reveal the occurrence of magnetization switching in the ZnO film. The magnetization switching in the presence of an electric field is ascribed to the converse magnetoelectric (ME) coupling that takes place between the electrical and the magnetic order parameters existing in the ZnO film. We have found the strain-driven magnetization change as evidenced by the butterfly shape of the magnetization vs the electric field curve. A saturation magnetization of 13.31 MA/m is obtained. Moreover, a significant value of the ME coupling coefficient (α) (1.61 × 10−7 s/m) has also been reported in this article. The emergence of electric field-induced magnetization in a single polycrystalline ZnO film is regarded to be a very promising aspect in designing high-density energy-efficient spintronic and different multifunctional devices. [ABSTRACT FROM AUTHOR]

Vapor deposition of halide perovskites presents high potential for scalability and industrial processing of perovskite solar cells. It prevents the use of toxic solvents, allows thickness control, and yields conformal and uniform coating over large areas. However, the distinct volatility of the perovskite organic and inorganic components currently requires the use of multiple thermal sources or two‐step deposition to achieve the perovskite phase. In this work, single‐source, single‐step MA1–xFAxPbI3 thin film deposition with tunable stoichiometry by pulsed laser deposition is demostrated. By controlling the laser ablation of a solid target containing adjustable MAI:FAI:PbI2 ratios, the room temperature formation of cubic α‐phase MA1–xFAxPbI3 thin films is demonstrated. The target‐to‐film transfer of the ablated species, including the integrity of the organic molecules and the desired MA+:FA+ ratio, is confirmed by x‐ray photoelectron spectroscopy and solid‐state NMR. Photoluminescence analysis further confirms the shift of the bandgap with varying the MA+:FA+ ratio. Finally, proof‐of‐concept n‐i‐p solar cells with 14% efficiency are demonstrated with as‐deposited non‐passivated pulsed laser deposition (PLD)‐MA1–xFAxPbI3. This study opens the path for future developments in industry‐compatible vapor‐deposition methods for perovskite solar cells. [ABSTRACT FROM AUTHOR]

This paper reports the fabrication of thin-film batteries which are composed of three stacking layers: LiCoO2, Li3PO4, and Li. First, a LiCoO2 layer is constructed on an electron-conductive substrate by pulsed laser deposition as a cathode. The crystallinity of the LiCoO2 layer is mainly controlled by the cationic ratio of Li and Co. Subsequently, an amorphous Li3PO4 layer with a high ionic conductivity is further deposited on the cathode LiCoO2 layer by radio frequency magnetron sputtering as a solid electrolyte. To avoid any possible damage which causes the formation of resistive species between LiCoO2 and Li3PO4, bias control of the substrate during Li3PO4 deposition is essential. Finally, a Li metal layer is deposited as an anode/current collector on the Li3PO4/LiCoO2 bilayer by resistive heating evaporation in a vacuum at an elevated temperature for the formation of a low resistive interface. The fabricated three-layer thin-film battery shows a high-rate capability when the LiCoO2 layer is a (104)-oriented epitaxial film. [ABSTRACT FROM AUTHOR]

The article explores the orientation-dependent electrochemical response of LaSrNiO4 (LSNO) epitaxial films by investigating the influence of growth orientation on electrochemical reactions. The study reveals that the resistance of (100)-oriented LSNO films can be modulated significantly by electrochemical reactions, while the resistance of (001)-oriented films remains largely unaffected. The results suggest that oxygen vacancies are produced in the NiO2 layer of LSNO during electrochemical reactions, with diffusion of oxygen ions occurring preferentially within the NiO2 layer. [Extracted from the article]

This study offers a comprehensive investigation into the fabrication of all-oxide-based magnetic tunnel junctions (MTJs) utilizing the focused ion beam (FIB) nanomachining method. The oxide thin films of SrTiO3 (STO), La 1 − x CaxMnO3 (LCMO) and La 1 − x SrxMnO3 (LSMO) were grown using pulsed laser deposition (PLD). Magnetization measurements at 5K revealed a notable difference in coercivity between LCMO and LSMO films, highlighting their suitability as electrodes in MTJ device fabrication. The deposited trilayer structure of LCMO/STO/LSMO exhibited heteroepitaxial growth, enabling the independent magnetic switching of electrode layers in the MTJ with the STO barrier layer. Conventional photolithography and ion milling were used to create a series of 4 μ m Hall bar tracks in the deposited films. Nanopillar devices, sized 250 nm × 250 nm, were successfully fabricated on these 4 μ m tracks by optimizing the FIB nanomachining technique. The fabricated MTJs demonstrated a high tunnel magnetoresistance (TMR) response, leading to the conclusion that the FIB nanomachining technique holds significant promise for the development of high-performance oxide-based spintronic devices. [ABSTRACT FROM AUTHOR]

Van der Waals heterostructures are set as strong contenders for post‐CMOS quantum materials engineering. A major step for their systematic exploration and exploitation of technological component demonstrators resides in their eased large‐scale design. In this direction, the growth of artificial van der Waals 2D superlattices is presented here such as (MoS2/WS2)n, (WS2/WSe2)n, and (MoS2/WSe2)n with unit cells repetitions reaching n > 10. The fabrication of these materials is enabled by a fully automated in‐situ pulsed laser deposition (PLD) tool. This approach provides cm2 scale homogeneous superlattices with on‐demand material parameters tailoring (layer number, order, and composition). The process is rapid and simple compared to manual pickup exfoliation methods or to sequential transfers of single layers grown by techniques such as chemical vapor deposition, allowing a large repetition of the unit cells in a "mille‐feuille" cake configuration. The computational exploration of this family of superlattice materials sheds light on the potential for optoelectronic property design by shaping the band‐structure landscape while taking into account the influential effects induced by proximity. Overall, this large‐area approach is proposed as an entry point for the systematic design of complex van der Waals heterostructures. [ABSTRACT FROM AUTHOR]

Indium tin oxide (ITO) is the leading transparent electrode material in displays and in photovoltaics. As both these markets are vast and rapidly expanding, the demand for alternative transparent conductive oxides (TCOs) is becoming increasingly urgent due to the limited availability of indium. Herein, aluminum‐doped zinc oxide (AZO) is revisited as a promising indium‐free TCO candidate. An industrial‐scale pulsed laser deposition (PLD) process is developed that produces highly conductive and transparent AZO films at room temperature, without the need for post‐deposition annealing. This PLD‐AZO films have excellent morphological, electrical, and optical properties, with sheet resistances of ≈ 55–25 Ω ϒ−1 for thin TCO thicknesses (around 100 to 200 nm, respectively), and absorptance from 400 to 1000 nm below 10%. We demonstrate the application of this highly conductive PLD‐AZO not only as a bottom contact but also as an effective top contact in perovskite solar cells, highlighting its versatility. The AZO‐based devices achieve performance and stabilities equivalent to that of ITO‐based. This findings demonstrate the robustness and potential of PLD‐deposited AZO layers in enhancing displays and PV production and facilitating the wider adoption of renewable and sustainable TCO alternatives in the expanding photovoltaics and displays markets. [ABSTRACT FROM AUTHOR]

Thin films based on tungsten oxide (WO3) were grown by nanosecond pulsed laser deposition on alumina printed-circuit boards to fabricate electrochemical sensors for nitrogen dioxide (NO2) detection. Samples exposed to thermal annealing (400 °C for 3 h) were also produced to compare the main properties and the sensor performance. Before gas testing, the morphology and structural properties were investigated. Scanning electron microscopy and atomic force microscopy showed the formation of granular films with a more compact structure before the thermal treatment. Features of the main WO3 phases were identified for both as-deposited and annealed samples by Raman spectroscopy, whereas X-ray diffraction evidenced the amorphous nature of the as-deposited samples and the formation of crystalline phases after thermal annealing. The as-deposited samples showed a higher W/O ratio, as displayed by energy-dispersive X-ray spectroscopy. An Arrhenius plot revealed a lower activation energy (0.11 eV) for the as-deposited thin films, which are the most electrically conductive samples, presenting a better gas response (30% higher than the response of the annealed ones) in the investigated NO2 concentration range of 5–20 ppm at the moderate device operating temperature of 75 °C. This behavior is explained by a larger quantity of oxygen vacancies, which enhances the sensing mechanism. [ABSTRACT FROM AUTHOR]

Experimentally achieving the first‐ever electric field periodic poling of single crystal barium titanate oxide (BTO, or BaTiO3) thin film on‐insulator is reported. Owing to the outstanding optical nonlinearities of BTO, this result is a key step toward achieving quasi‐phase‐matching (QPM). First, the BTO thin film is grown on a dysprosium scandate substrate using pulsed laser deposition with a thin layer of strontium ruthenate later serving as the bottom electrode for poling. The characterization of the BTO thin film using x‐ray diffraction (XRD) and piezo‐response force microscopy to demonstrate single crystal, single domain growth of the film that enables the desired periodic poling, are presented. To investigate the poling quality, both non‐destructive piezo force response microscopy and destructive etching‐assisted scanning electron microscopy (SEM) are applied, and it is shown that high quality, uniform, and intransient poling with 50% duty cycle and periods ranging from 2 µm to 10 µm is achieved. The successful realization of periodic poling in BTO thin film unlocks the potential for highly efficient nonlinear processes under QPM that seemed far‐fetched with prior polycrystalline BTO thin films which predominantly relied on efficiency‐limited random or non‐phase matching conditions and is a key step toward integration of BTO photonic devices. [ABSTRACT FROM AUTHOR]

The chemical and electronic interactions at metal/oxide heterojunctions is pivotal in determining the electronic properties of oxide devices utilized in microelectronics, catalysis, and photovoltaic systems. In this study, interfacial oxidation migrations within a model heterostructure system, consisting of a La0.7Sr0.3MnO3 film overlaid by various metallic (Ti, Al, Cu, Ag, and Au) ultrathin layers are systematically investigated. It is experimentally demonstrated that at elevated deposition temperature, the oxygen‐active ultrathin overlayers of base metals such as Ti and Al significantly derive oxygen from the underlying La0.7Sr0.3MnO3 film, inducing a perovskite to brownmillerite phase transition in the underlying functional oxide film. Conversely, no structural transitions are observed for La0.7Sr0.3MnO3 film when it is capped by noble metals (Au, Ag), which possess relative high oxidation formation energy. These observations are crucial for the development of novel crystalline and electronic architectures in metal/oxide heterostructures, offering a refined approach to modulate interfacial reactivity without compromising the functionality of oxide‐based heterojunction devices. [ABSTRACT FROM AUTHOR]

In this work, we have investigated the resistive switching (RS) properties of metal-insulator-metal (MIM) RRAM (resistive random-access memory) devices based on Hafnium Oxide (HfO2) films. A systematic study on the effect of substrate temperature on the crystallinity and its correlation with RS behaviour of HfO2 films deposited on platinized silicon using the Pulsed Laser Deposition (PLD) has been performed. Grazing-incidence X-ray diffraction and X-ray reflectivity techniques were employed to analyse the phase formation and the thickness of the films, respectively. The films were deposited at two different substrate temperatures 400 °C and 700 °C. A lower substrate temperature led to an amorphous film while the higher substrate temperature resulted in a polycrystalline film. The effect of change in amorphous to polycrystalline nature of HfO2 films with substrate temperature was studied on RS behaviour of these films. To assess the RS behaviour, DC electrical characterization was conducted on stacked W/HfO2/Pt thin films. The electrical characterization revealed forming-free bipolar RS behavior in both the films along with a digital SET and gradual RESET. The resistance of the films was found to be dependent on phase and microstructure which in turn depends upon substrate temperature. This study would be useful for the optimization of RS behaviour by tuning the crystallinity of the HfO2 films through processing temperature. [ABSTRACT FROM AUTHOR]

Cadmium Selenide CdSe thin films were deposited on (7.5x1.3x0.1 cm³) glass substrates and (1x1 cm²) p-type silicon substrates using pulsed laser deposition technique (Nd: YAG laser beam with 80 mJ energy, λ = 1064 nm). Then, they were annealed at 300 °C for 1 h to get diodes as visible light detectors. Some of these samples (diodes) were exposed to different intervals (5, 7, 9, 12) days of neutron radiation using (241Am-10Be) source with a flux of 3x105 n/cm².s and energy of 5.71 MeV. For comparison purposes, the other diodes were kept without any irradiation The morphological and electrical properties of these samples were studied by XRD, FE-SEM and I-V measurements. Results have shown all these thin films exhibit a hexagonal structure. However, there is a slight shift in the preferred orientation (100) for the irradiated films. Also, there was a new (102 - SiO2) peak that appeared in the irradiated thin film pattern. The crystallite size of pristine and (5, 7, 9, 12) days irradiated CdSe thin films were (26.9, 18.3, 24.9, 20.3 and 24.5) nm respectively, whereas, the mean particle size of the pristine film was 37 nm whereas for the irradiated films 53, 64, 73 and 92 nm. Results also show that the band gap of these samples increased from 2.17 eV for pristine thin films to 2.3, 2.48, 2.25, and 2.3 eV for the irradiated thin films. On the other hand, the results of I-V characteristics show the dark/light current. The current under illumination increases when exposed to small values of neutron radiation then it decreases with higher values of exposure. In contrast, the dark current decreases significantly with the irradiation. The effect of the irradiation was clear on the response/recovery period for all devices. Nevertheless, it was more profound in the response/recovery time of pristine devices. Also, the photo-responsivity of the pristine device was larger than the other devices and it was decreased with increasing absorbed doses. [ABSTRACT FROM AUTHOR]

To demonstrate the feasibility of obtaining low-molecular-weight organic films (below 200 Da) using non-solvent PVD processes, glucose layers were produced via pulsed laser deposition (PLD) and pulsed electron beam deposition (PED) methods. Glucose was chosen due to its fundamental role in various biological processes, and because this low-molecular-weight compound is a solid at room temperature, which is required for both techniques. The physical and chemical structures of the deposited glucose layers were characterized by optical, scanning electron, and atomic force microscopy, as well as by X-ray diffraction, X-ray photoelectron, and infrared spectroscopy. Both PLD and PED methods resulted in glucose layers with good chemical structure preservation (with minor oxidation observed in PED) while yielding films with distinct physical properties. This opens up the possibility of tailoring organic layers with specific characteristics depending on the application, by choosing the deposition method. [ABSTRACT FROM AUTHOR]

This paper presents an innovative exploration of advanced configurations for enhancing the efficiency of metallic and superconducting photocathodes (MPs and SCPs) produced via pulsed laser deposition (PLD). These photocathodes are critical for driving next-generation free-electron lasers (FELs) and plasma-based accelerators, both of which demand electron sources with improved quantum efficiency (QE) and electrical properties. Our approach compares three distinct photocathode configurations, namely: conventional, hybrid, and non-conventional, focusing on recent innovations. Hybrid MPs integrate a thin, high-performance, photo-emissive film, often yttrium or magnesium, positioned centrally on the copper flange of the photo-injector. For hybrid SCPs, a thin film of lead is used, offering a higher quantum efficiency than niobium bulk. This study also introduces non-conventional configurations, such as yttrium and lead disks partially coated with copper and niobium films, respectively. These designs utilize the unique properties of each material to achieve enhanced photoemission and long-term stability. The novelty of this approach lies in leveraging the advantages of bulk photoemission materials like yttrium and lead, while maintaining the electrical compatibility and durability required for integration into RF cavities. The findings highlight the potential of these configurations to significantly outperform traditional photocathodes, offering higher QE and extended operational lifetimes. This comparative analysis provides new insights into the fabrication of high-efficiency photocathodes, setting the foundation for future advancements in electron source technologies. [ABSTRACT FROM AUTHOR]

Integrating epitaxial BaTiO3 (BTO) with Si is essential for leveraging its ferroelectric, piezoelectric, and nonlinear optical properties in microelectronics. Recently, heterogeneous integration approaches that involve growth of BTO on ideal substrates followed by transfer to a desired substrate show promise of achieving excellent device‐quality films. However, beyond simple demonstrations of the existence of ferroelectricity, robust devices with high endurance are not yet demonstrated on Si using the latter approach. Here, using a novel two‐step approach to synthesize epitaxial BTO using pulsed laser deposition on water‐soluble Sr3Al2O6 (on SrTiO3 substrates), successful integration of high‐quality BTO capacitors on Si is demonstrated, with remanent polarisation Pr = 7 µC cm−2, coercive field Ec = 150 kV cm−1, ferroelectric and electromechanical endurance of > 106 cycles. The study further addresses the challenge of cracking and disintegration of thicker films by first transferring a large area (5 mm x 5 mm) of the templated layer of BTO (≈30 nm thick) on the desired substrate, followed by the growth of high‐quality BTO on this substrate, as revealed by high‐resolution X‐ray diffraction (HRXRD) and high‐resolution scanning transmission electron microscopy (HRSTEM) measurements. These templated Si substrates offer a versatile platform for integrating any epitaxial complex oxides with diverse functionalities onto any inorganic substrate. [ABSTRACT FROM AUTHOR]

Wafer-scale Mesoporous GaN (MP-GaN) distributed Bragg reflectors (DBRs) with high reflectivity (>99 %) are prepared by electrochemical etching, and then are used as the substrate in growth of large-area europium (Eu) doped Ga 2 O 3 thin films via the pulsed laser deposition (PLD) technology. X-ray diffraction analysis shows that all Ga 2 O 3 thin films with different doping concentration have monoclinic β-Ga 2 O 3 structures with [−201] orientation. The angle of β-Ga 2 O 3 (−201) peak decreases as Eu contents increases, which is due to the fact that Eu3+ substituting for Ga3+ rises the lattice constant of β-Ga 2 O 3. With the increase of Eu doping, the photoluminescence (PL) of the Ga 2 O 3 thin film is enhanced. The epitaxial relationship is β-Ga 2 O 3 (−201) || GaN (0001) with β-Ga 2 O 3 [010] || GaN [-12-10]. Compared to the sample without DBRs, wafer-scale Ga 2 O 3 thin films with MP-GaN DBRs exhibit a markedly increased PL intensity, which is attributed to improved internal quantum efficiency (IQE) of Ga 2 O 3 thin films and enhanced light extraction efficiency (LEE) related to the light reflection effect of MP-GaN DBRs. [ABSTRACT FROM AUTHOR]

Delafossite CuCrO2 (CCO), CuCr0.96V0.04O2 (CCVO) thin films were successfully prepared on Si (100) substrates, using the pulsed laser deposition technique. The effect of doping was studied using x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), temperature-dependent resistivity measurements, and I–V characteristics. The XRD results confirmed the single-phase rhombohedral structure of the prepared thin films, and the XAS results conveyed the mixed Cu+ and Cu2+ ions in the CCVO and CCO samples. The valence state of Cr was unaltered under the doping effects and remained + 3 (i.e., Cr+3). The modified hybridization of the O 2p orbitals with the metal d (V, Cr,) orbitals was confirmed in the O K-edge spectra. Insertion of V5+ ions in the CCO lattice introduced an electron doping effect. Thus, the basic p-type character of CCO was affected by the V doping and, therefore, increases in the resistivity or decreases in the p-type character were observed in the I–V measurements. From this study; the method of selective mono-doping can be a useful tool to tailor the bandgap and the type of conductivity in other delafossite semiconductors. [ABSTRACT FROM AUTHOR]

This study investigates the optical properties of yttrium ferrite thin films fabricated via pulse laser deposition. Yttrium orthoferrite, a ferrimagnetic material known for its potential applications in spintronics and photonics, was deposited on single-crystal substrates under controlled conditions to analyze its optical characteristics. The influence of deposition time on the film quality and optical properties was examined. Atomic force microscopy in contact mode revealed surface roughness variations up to 35 nm, indicating the films' ability to cover substrate defects. Reflectance measurements determined the optical band gap, which decreased from 3.17 eV for thinner films (44 nm) to 2.91 eV for thicker films (93 nm). Forbidden electronic transitions were also observed, attributed to heteroepitaxial growth and phonon interactions. These results demonstrate the effect of film thickness on morphology and optical properties, making YFeO3 films promising for a range of optoelectronic applications. [ABSTRACT FROM AUTHOR]

Traditional silicon are expected to be integrated with emerging halide perovskites to form semiconductor heterostructures, which can facilitate the realization of more modern electronics and optoelectronics but not only solar cells. Currently, the deposition of perovskite films onto silicon substrates predominantly relies on spin-coating techniques, which inherently pose challenges, such as stringent growth prerequisites, compromised film integrity, and inability to foster robust interfacial tuning between the silicon and perovskite films. In this Letter, we report the epitaxial growth of a (100)-oriented CsPbBr3 film directly on a p-type silicon (100) substrate by pulsed laser deposition (PLD), which offers precision control over the interface between the substrate and film. This p-Si/n-CsPbBr3 semiconductor heterostructure manifests distinct p–n heterojunction behavior, characterized by current rectification in the dark state, which indicates the efficient charge separation and transport mechanisms. The device demonstrates visible photodetection capabilities from 400 to 700 nm, showcasing versatility in spectral response. Notably, under 520 nm laser illumination, the device exhibited a remarkable responsivity of 780 mA/W due to electron tunneling from silicon to perovskite film as a direct result of the epitaxial interface, coupled with millisecond-scale response and recovery times, highlighting its potential for high-speed and sensitive photodetector applications. These findings underscore the significant promise of PLD-mediated growth of high-quality epitaxial halide perovskite films on silicon substrates and the formation of heterostructure as a viable route toward complex thin superlattices and integrated devices. [ABSTRACT FROM AUTHOR]

BiFeO3 (BFO) application in flexible wearable devices is garnering interest because of its unique ferroelectric and magnetic properties. However, the integration of high-quality BFO films onto flexible substrates presents significant technical challenges. Here, we successfully fabricated high-quality BFO films on mica substrates by using pulsed laser deposition, and report the fatigue characteristics of BFO films on flexible substrates for the first time. The results demonstrated that, after 108 bipolar switching cycles, the polarization only degraded by 0.28%, indicating superior fatigue characteristics compared to previously reported BFO films. Additionally, the device ferroelectric properties remained largely unchanged, with a bending radius of 3.5 mm. The fabricated flexible Pt/BFO/La0.65Sr0.35MnO3(LSMO)/SrTiO3(STO)/mica non-volatile memory devices exhibited mechanical flexibility and fatigue resistance. These findings not only highlight the potential of flexible BFO films for wearable electronic devices and flexible memory devices, they also provide valuable insight for the future development of high-performance flexible ferroelectric materials. [ABSTRACT FROM AUTHOR]

As a promising 2D material, bismuth oxyselenide (Bi2O2Se) has demonstrated significant potential to overcome existing technical barriers in various electronic device applications due to its unique physical properties like high symmetry, adjustable electronic structure, and ultra-high electron mobility. However, the rapid growth of Bi2O2Se films down to a few atomic layers with precise control remains a significant challenge. In this work, the growth of two-dimensional (2D) Bi2O2Se thin films by the pulsed laser deposition (PLD) method is systematically investigated. By controlling temperature, oxygen pressure, laser energy density, and laser emission frequency, we finally prepare atomically thin and flat Bi2O2Se (001) thin films on the (001) surface of SrTiO3. Importantly, we provide a fundamental and unique perspective toward understanding the growth process of atomically thin and flat Bi2O2Se films, and the growth process primarily proceeds in four steps. Moreover, the combined results of the crystallinity quality, surface morphology, and the chemical states demonstrate the PLD-growth of high-quality Bi2O2Se films in a controllable and fast mode. [ABSTRACT FROM AUTHOR]

We report the pulsed laser deposition (PLD) of nanocrystalline/amorphous homo-composite BaTiO3 (BTO) films exhibiting an unprecedented combination of a colossal dielectric constant (εr) and extremely low dielectric loss (tan δ). By varying the substrate deposition temperature (Td) over a wide range (300–800 °C), we identified Td = 550 °C as the optimal temperature for growing BTO films with an εr as high as ~3060 and a tan δ as low as 0.04 (at 20 kHz). High-resolution transmission electron microscopy revealed that the PLD-BTO films consist of BTO nanocrystals (~20–30 nm size) embedded within an otherwise amorphous BTO matrix. The impressive dielectric behavior is attributed to the combination of highly crystallized small BTO nanograins, which amplify interfacial polarization, and the surrounding amorphous matrix, which effectively isolates the nanograins from charge carrier transport. Our findings could facilitate the development of next-generation integrated dielectric devices. [ABSTRACT FROM AUTHOR]

Development of artificial opto‐electronic synaptic devices plays a crucial role for the practical implementation of energy‐efficient, parallel processing of human brain. In this article, two terminal inter‐digitated devices are fabricated on Gallium oxide (Ga2O3) thin films grown on sapphire substrates by pulsed laser deposition (PLD) technique to study its ability to mimic biological synaptic behaviors. The layers are found to exhibit long persistent photo‐conductivity (PPC) effect, which is identified to be the key parameter to replicate the behavior of biological synapses. Channel resistance and PPC time constants should also be optimized to improve the efficiency of response and energy consumption of synaptic devices. It has been observed that both conductivity and the PPC decay time of Ga2O3‐films can be controlled by varying oxygen pressure (∅O2)$({{{\emptyset }_{{{O}_2}}}})$ and growth temperature (TG). These devices demonstrate their ability to perform paired pulse facilitation (PPF) at very low applied bias in mV‐range. They can mimic biological synapses showing short‐to‐long‐term memory transition (STM‐to‐LTM) and learning‐forgetting behavior. One of these devices is found to show synaptic behavior with the energy consumption of as low as 71fJ electrical and 21nJ optical per synaptic event. These findings thus strengthen the candidature of Ga2O3 films for the development of next‐generation opto‐electronic neuromorphic devices and systems. [ABSTRACT FROM AUTHOR]

Micro‐mechanical resonators are building blocks of a variety of applications in basic science and consumer electronics. This device technology is mainly based on well‐established and reproducible silicon‐based fabrication processes with outstanding performances in term of mechanical Q‐factor and sensitivity to external perturbations. Broadening the functionalities of micro‐electro‐mechanical systems (MEMS) by the integration of functional materials is a key step for both applied and fundamental science. However, combining functional materials with silicon‐based devices is challenging. An alternative approach is directly fabricating MEMS based on compounds inherently showing non‐trivial functional properties, such as transition metal oxides. Here, a full‐oxide approach is reported, where a high‐Tc$\rm {T_c}$ superconductor YBa2Cu3O7 (YBCO) is integrated with high Q‐factor micro‐bridge resonators made of single‐crystal LaAlO3 (LAO) thin films. LAO resonators are tensile strained, with a stress of about 350 MPa, show a Q‐factor above 200k, and have low roughness. YBCO overlayers are grown ex situ by pulsed laser deposition and YBCO/LAO bridges show zero resistance below 78 K and mechanical properties similar to those of bare LAO resonators. These results open new possibilities toward the development of advanced transducers, such as bolometers or magnetic field detectors, as well as experiments in solid state physics, material science, and quantum opto‐mechanics. [ABSTRACT FROM AUTHOR]