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Laser trimming promises an increasing yield in microfabrication for the high performance Micro Electro-Mechanical Systems (MEMS) resonant devices by overcoming manufacturing tolerances and tuning sensors or actuators for certain operating conditions. How to achieve a high precision and efficiency trimming at low cost is the critical issue that the technical communities are most concerned. In this paper, we proposed an automatic laser trimming system for silicon MEMS devices based on a picosecond laser source and image recognition technique (IRT). Through the design of laser focusing optical path and coaxial imaging optical path, the observation of laser machining process is realized. A set of picosecond laser trimming parameters is determined by experiments, which enables a 4 $\mu {\mathrm{ m}}$ width trench on the silicon resonator. Compared with the femtosecond laser trimming systems, the cost of the pico-laser system is reduced by more than 60%. The shape matching algorithm based on OpenCV and the chord-to-point distance accumulation (CPDA) algorithm for MEMS resonators image measurement solve the problem of inefficiency of manual trimming for complex resonators. A dual-mass tuning fork resonator is used to demonstrate the feasibility of the trimming approach. It is shown that the system realizes a fine-tuning (< 0.3Hz) of the resonant frequencies. The trimming time of a single device using the automatic trimming method is reduced from more than 1 hour manual trimming to less than 1 minute. Finally, the structural stiffness imbalance of tuning fork resonator caused by the manufacturing error is eliminated, which verifies the feasibility of the system. [ABSTRACT FROM AUTHOR]

Cerium-substituted yttrium iron garnet (Ce:YIG) thin films are promising magneto-optical (MO) materials for the application in optical isolators. Ce:YIG can be grown on the YIG seed layer, and the change of layer thickness ratio for Ce:YIG to YIG may result in different magnetic properties. In this work, Ce:YIG (Ce1Y2Fe5O12) to YIG (Y3Fe5O12) bilayer films, with different thickness ratios of 2:1, 4:1, 6:1, and 8:1, were grown by pulsed laser deposition (PLD); 2:1 and 4:1 films consist of pure YIG phase; 6:1 and 8:1 films consist of YIG phase, Y2Fe4O9 phase with hexagonal structure, and Y2O3 phase with cubic structure. Y2Fe4O9 and Y2O3 phases induce the decrease of saturation magnetization ($M_{s}$). The concentration of Fe2+ and Ce4+ ions increases with layer thickness ratio increasing, resulting in the decrease of saturation magnetization ($M_{s}$), coercivity ($H_{c}$), and magnetic anisotropy energy ($E$). It is found that the best magnetic properties, including $H_{c}$ (26.9 Oe), $M_{s}$ (140.6 emu/cm3), and $E$ (257.5 J/cm3), are obtained in the 2:1 film. [ABSTRACT FROM AUTHOR]

Microultrasound (micro-US) has become an invaluable tool for preclinical research and in emerging applications in clinical diagnosis and treatment guidance. Several such applications can benefit from arrays with a small footprint and endoscopic form factor. However, critical challenges arise in making electrical connections to array elements in such spatial constraints. In this work, we describe a method to pattern a high-density flexible circuit cabling on a copper-on polyimide film, using laser ablation of a polymer resist and wet etching, and then demonstrate a connection to a micro-US array. We investigate laser ablation process parameters and evaluate the ability to consistently pattern continuous copper traces. A minimum 30- $\mu \text{m}$ pitch was achieved with 5- $\mu \text{m}$ -wide electrode lines, and continuity of a 5-m-long trace is demonstrated. A flexible circuit with 30-mm-long traces with 30- $\mu \text{m}$ line and 30- $\mu \text{m}$ space before fan-out was fabricated to connect in an interleaved manner to a 32-element array with 30- $\mu \text{m}$ element pitch. Metal deposition and laser ablation were used to connect and pattern the element electrodes to the copper traces of the flexible circuit. Electrical and acoustic measurements show good yield and consistent impedance across channels. Element pulse-echo tests demonstrated device functionality; the two-way pulse had 43-MHz center frequency and 40% fractional bandwidth (−6 dB). The proposed manufacturing methods facilitate the prototyping and fabrication of flexible endoscopic or small-footprint micro-US devices. [ABSTRACT FROM AUTHOR]

Ferroelectrics (FEs) are increasingly used in nonvolatile memory applications. However, the impact of the electric dipole switching on its material parameters, in particular on the dielectric response, is not fully understood. In this work, an analytical model, linking the dielectric response to the potential energy curve, is first used to qualitatively illustrate the nonconstant evolution of the dielectric response with applied electric field. Increasing precision, we then show from first-principles density functional theory simulations that defect-free FE materials undergo changes in potential energy near the FE switching that lead to vibrational modes softening, which impacts the dielectric response. In particular, we observe that the dielectric response $\varepsilon $ of an FE material with antialigned polarization increases as the applied electric field increases toward the coercive field. We incorporate this new insight in the time-dependent NLS-based predictions and demonstrate that this evolution of the dielectric response right before polarization reversal is required for a proper match between experiment and prediction of the capacitance–voltage (CV) characteristics of the metal–ferroelectric–metal (MFM) capacitor. [ABSTRACT FROM AUTHOR]

Top-gated (TG) molybdenum disulfide (MoS2) field-effect transistors (FETs) suffer from surface damage, unintentional doping, and other defects introduced to the MoS2 channel during the direct deposition of the gate dielectric. In addition, the delicate MoS2 cannot withstand high-temperature processing or annealing. To overcome these obstacles, a novel path to prepare TG MoS2 negative-capacitance (NC) FETs is proposed in this study. A ferroelectric HfZrO2 (HZO) is first deposited on the mica flake by pulsed laser deposition (PLD) and then annealed by rapid thermal processing. Subsequently, the HZO/mica stack is integrally transferred onto the MoS2 surface, without needing to expose the MoS2 flake to harsh temperatures or PLD environments. TG multilayered MoS2 NCFETs with the HZO/mica stack are fabricated and demonstrate stable NC effects and superior performance with a subthreshold swing (SS) of 49 mV/dec, ON/OFF current ratio above 107, and anticlockwise hysteresis voltages of 64 mV, which are attributed to vital contributions from the damage-free mica/MoS2 van der Waals heterojunction interface and reasonable capacitance matching between the mica dielectric and the ferroelectric HZO film. Moreover, the experimental results of the dual-gate MoS2 transistor modulated by the bottom gate show that a positive bottom-gate bias can increase drain current and decrease hysteresis voltage, and a negative bottom-gate bias can reduce SS. Therefore, the proposed approach changes the current situation that the PLD method is hardly used to fabricate TG MoS2 transistors and opens a new window for nanoelectronics. [ABSTRACT FROM AUTHOR]

In this work, a hybrid combination structure of fin-channel array, gate-recessed structure, and LiNbO3 ferroelectric charge trap gate-stacked oxide layers was utilized in AlGaN/gallium nitride (GaN) enhancement-mode metal–oxide–semiconductor high-electron-mobility transistors (E-MOSHEMTs). The C+ ferroelectric polarization of the LiNbO3 blocking layer, deposited by a pulsed laser deposition system, increased the stored amount of electron charges in the HfO2 charge trap layer, leading to a high positive threshold voltage of 2.9 V for the enhancement-mode operation. In studying the initialization features, it was found that the threshold voltage shifted to a more positive voltage with an increase of initialization voltage. The devices changed to enhancement-mode from depletion-mode when the gate voltage larger than 4 V was applied to initialize the devices. Compared with a planar channel structure, the devices with 500-nm-wide fin-channel array structure improved the maximum extrinsic transconductance from 89.5 to 110.9 mS/mm, the subthreshold swing from 224.8 to 120.5 mV/dec, the extrinsic unit gain cutoff frequency from 5.0 to 7.4 GHz, the maximum oscillation frequency from 9.1 to 11.7 GHz, and the normalized noise power from $1.9\times 10^{-{14}}$ to $2.5\times 10^{-{15}}$ Hz−1. [ABSTRACT FROM AUTHOR]

Implantable medical electronics are almost exclusively packaged in titanium shells to ensure reliability and longevity. Additional silicone rubber encapsulation improves structural biocompatibility and limits the diffusion of ion from the body to package materials. These capsules must be hermetically sealed and provide electrical feedthroughs that are insulated against each other by connecting ceramic parts. In this study, a novel RoHS-compliant low-temperature soldering process is presented, allowing the required assembly. Tungsten/titanium as adhesion material and platinum as wetting layer were deposited by physical vapor deposition as thin films and were structured by a rapid prototyping laser process. Different devices were soldered with a tin-silver alloy below 300 °C resulting in low thermal stress. The platinum acts as an excellent solder pad. A 50-nm tungsten/titanium adhesion promoter efficiently strengthens the bond to the titanium substrate. The results show that the platinum layer must be thicker than 300 nm to guarantee high bonding strength. Analyses of cross sections of the joint show occurrence of diffusion of platinum and silver during the soldering process. At soldering times above 30 s, a large intermetallic layer forms at the soldering contact, which is prone to crack formation. Likewise, intermixing of tungsten and platinum were observed but without detrimental effects. Limitations in solder times are therefore advisable, for example, by introduction of automatic processes. Soaking tests were performed with sealed capsules in water at 60 °C for one year without measurable increase of humidity inside the package. In the used accelerated aging model, this would correspond to a hermetic sealing of about five years at 37 °C. [ABSTRACT FROM AUTHOR]

Nano-Ag sintering is a promising die-attach technology for the wide bandgap semiconductive power devices, while the high cost of nanosilver limits industrial application. Reducing bondline thickness (BLT) is effective for cost-saving but its effects on reliability have been rarely studied, especially at high-temperature operation. In this work, an organic-free nanostructured silver film was prepared by pulsed laser deposition (PLD) for various BLT joints. The effect of BLT (3.5–60 μm) on the high-temperature reliability of die-attached modules was systematically investigated. The results indicated that with the increase of BLT, the shear strength and power cycling number of joints both increased. The optimal BLT ranged in 25–50 μm considering both reliability and cost. It was very interesting to find that the connection ratio along the BLT direction existed two valleys at the die- and DBC-bondline interfaces, which clearly corresponded to the crack propagating in the power cycling test. [ABSTRACT FROM AUTHOR]

We measure the electrical performance and stability of indium tin zinc oxide (ITZO) thin-film transistors (TFTs), respectively, covered with a passivation layer (PVL) of aluminum oxide (Al2O3) or scandium oxide (Sc2O3) prepared by pulsed laser deposition (PLD). The devices with the Sc2O3 PVL exhibit both satisfactory electrical performance and stability with a field effect mobility of 16.4 cm2/Vs, threshold voltage of 1.0 V, subthreshold swing of 0.09 V/decade, and especially, a minimum threshold voltage shift of 0.7 and −1.6 V under negative bias temperature stress (NBTS) and positive bias temperature stress (PBTS), respectively. This may be attributable to the suppression of oxygen vacancy formation and excellent capacity to protect the channel from environmental effects. Although the devices with the Al2O3 PVL show similar electrical performance, their stability is worse than that of the devices with Sc2O3. This shows the excellent potential of Sc2O3 thin films as a PVL. [ABSTRACT FROM AUTHOR]

Optical emission spectroscopy (OES) has been used as an in-situ method to monitor the film deposition carried out using a combination of two plasma-assisted techniques; pulsed laser deposition (PLD) and magnetron sputtering (MS). In this work, the plasmas produced during the PLD ablation of a gold target in an argon atmosphere and its simultaneous use with MS of ZnO were characterized by OES. Neutral atoms of Au, Ar, and Zn and ions of Au were identified, and the temporal and spatial evolution of their emission lines was studied along the axis of the PLD plasma expansion. During the PLD of Au an increment in the emission intensity of neutral Au near the substrates, as a function of the laser pulse fluence, demonstrated resputtering of the Au deposit by the high energy species produced by PLD. When the combination of PLD of Au and MS of ZnO was performed, a similar increment was observed in the emission intensity, but in this case of neutral Zn that was caused by the preferential resputtering of Zn from the ZnO–Au deposit. The MS plasma neither significantly affect the PLD plasma expansion nor did it affect the resputtering of the films. [ABSTRACT FROM AUTHOR]

Here we report the fabrication of normal metal – insulator – superconductor (NIS) tunnel junctions using superconducting titanium nitride grown by pulsed laser deposition (PLD). The films for NIS junction fabrication were deposited on two different substrates: silicon nitride film and magnesium oxide. TiN films were characterized by means of electrical transport measurements, and films with superconducting transition temperatures above the liquid helium boiling point were chosen for fabrication of NIS junctions. Tunnel junction devices were successfully fabricated using electron beam lithography and shadow evaporation techniques. The insulator layer formation was performed using two different approaches: the tunnel barrier was either formed by direct oxidation of TiN, or by fabrication of an additional aluminum oxide layer. Devices fabricated by direct oxidation showed much more transparent barriers and slightly higher subgap currents, but both types of devices could be used for thermometry. Further optimization of the direct oxidation process may allow electric cooling applications in the future. [ABSTRACT FROM AUTHOR]

In this study, the imaging of metal ions and nanoparticles deposited on a structured silicon surface was investigated using a laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). For application, 8 × 8 Petri-dish pillars, each with a diameter of 250 μm and height of 300 μm, were constructed on a silicon wafer. The etched pillar surface took a droplet of approximately 4.3 nL aqueous solution from a capillary tip through the surface-liquid attraction. The dissolved materials were found at the intersecting edge of pillar bottom after evaporation, and their positions were matched with the peaks of elements in the mass spectrum for imaging. Results suggest that the trace contaminants in the cleaning solution are gathered at the intersecting edges of the patterned wafer, and the multi-elemental images of the contaminants can be successfully obtained using LA-ICP-MS. [ABSTRACT FROM AUTHOR]

Strained oxygen-deficient perovskite SrFeO $_{3 - \delta }$ (SFO) films have been epitaxially grown by pulsed laser deposition (PLD) on SrTiO3 (STO) (001) substrates. Oxygen deficiency of the films in comparison with the stoichiometric perovskite SrFeO3 is manifested in the increased lattice parameter, $c = 3.97$ Å, the decreased mass density, $\rho = 4.825$ gcm−3, and the presence of Fe3+ cations. The SFO perovskite structure is monoclinically distorted with an increase of the film thickness, resulting in the reduction of the total magnetic moment. A wasp-waisted hysteresis loop and a negative exchange bias are observed for the 69 nm thick film due to the possible magnetic sublayers arising from a proper monoclinically distorted surface layer and a substrate-locked core layer. [ABSTRACT FROM AUTHOR]

We report on temperature-dependent broadband ferromagnetic resonance studies of magnetite (Fe3O4) film of thickness 30 nm grown on magnesium gallate [MgGa2O4(001)] single crystal substrate by pulsed laser deposition. The isotropic point, i.e., the temperature at which magnetocrystalline anisotropy vanishes, is found to be approximately 120 K, which is 10 K lower than the bulk value. The Verwey transition is close to 110 K, again about 10 K lower than the bulk crystal value. Below the Verwey transition temperature, the uniaxial anisotropy of the monoclinic phase increases gradually and asymptotically approaches a constant value indicating a smooth structural transition rather than a sudden change. Resonance linewidth and effective damping increase abruptly below 110 K. The effective damping constant is determined to be ~0.01 and is independent of temperature from 300 K to 120 K. [ABSTRACT FROM AUTHOR]

We report the magnetic properties of yttrium iron garnet (YIG) thin films grown by pulsed laser deposition technique. The films were deposited on Si (100) substrates in the range of 15–50 nm thickness. Magnetic characterizations were investigated by ferromagnetic resonance spectra. Perpendicular magnetic easy axis was achieved up to 50 nm thickness. We observed that the perpendicular anisotropy values decreased by increasing the film thickness. The origin of the perpendicular magnetic anisotropy (PMA) was attributed to the texture and the lattice distortion in the YIG thin films. We anticipate that perpendicularly magnetized YIG thin films on Si substrates pave the way for a cheaper and compatible fabrication process. [ABSTRACT FROM AUTHOR]

In this article, we have developed an amorphous CuNiSnO (a-CNTO), which is a p-type amorphous oxide semiconductor (AOS). The a-CNTO thin films were deposited by the pulsed laser deposition method, having high amorphous quality with a rather smooth surface. The a-CNTO films grown at 100 °C exhibited the smoothest surface (root-mean-square roughness of 0.25 nm), highest visible transparency (~85%), and most favorable p-type conductivity (hole concentration of ~1015 cm−3), which are very suitable for electronic device fabrication. Thus, the obtained p-type a-CNTO thin-film transistors (TFTs) have an ON-to- OFF current ratio of ~ 1.2 × 105, the threshold voltage of −2.3 V, the field-effect mobility of 1.37 cm2/Vs, and subthreshold swing of 0.70 V/decade. As a new kind of p-type AOS, the achievement of the p-type a-CNTO TFTs and the low-temperature processes may open the door for practical applications in transparent and flexible electronics. [ABSTRACT FROM AUTHOR]

Hybrid integration of unconventional optical materials is arguably a promising way to substantially extend a range of chip functionalities on traditional silicon-based platforms. Especially, functional oxides are very promising because they exhibit many attractive properties, including superconductivity, piezoelectricity, ferroelectricity, and optical effects. In this article, we demonstrate hybrid photonic platform with an Erbium-doped (Er-doped) Yttria-Stabilized Zirconia (YSZ) thin film used as an active luminescent cladding on top of low-loss Silicon Nitride (SiN) waveguides. This active layer has been grown by a pulsed laser deposition (PLD) technique. Optical characterizations via photoluminescence (PL) measurements were performed in both normal and in-plane light incidence to demonstrate strong near-infrared (near-IR) emission of Er ions in the Er:YSZ thin film. Moreover, we also observed an intense in-plane guided PL emission in visible and near-IR wavelengths from hybrid Er:YSZ-on-SiNx waveguides. These results pave the way towards rare-earth-doped YSZ structures on silicon-based platforms, thereby affording required function versatility for future photonic integrated circuits. [ABSTRACT FROM AUTHOR]

We report on the hybrid ZnO/AlN/Si heterostructure-based ultraviolet (UV) photodetectors with infrared- and visible-blind characteristics. The heterostructure was formed by depositing ZnO thin films on Si (111) substrate by introducing an AlN as an intermediate layer. The ZnO film has been grown epitaxially on the underlying substrate with the improved crystallinity and excellent optical properties. The vertical transport properties of the ZnO/AlN/Si heterojunction under dark and light illumination demonstrate the intrinsic infrared- and visible-blind characteristics with excellent ultraviolet responsivity. The heterostructure exhibits a high UV responsivity of 14.5 A/W with UV-to-Infrared rejection ratio of nearly 4 orders of magnitude. The vertical electrical transport properties across the heterostructure are dominated by the holes in the reverse bias condition, whereas the transport of electrons in the forward bias is hindered at the ZnO/AlN interface due to an existence of huge conduction band offset between ZnO and AlN layers. The AlN intermediate layer acts as an electron blocking layer which allows the hole to transport across the heterostructure in the reverse bias condition. [ABSTRACT FROM AUTHOR]

An approach for determining the optimal laser parameters (i.e., pulse energy, focused spot size, wavelength, and pulse duration) for correlating single-event transients induced via two-photon absorption (TPA) and heavy ions is presented. The approach focuses on identification and extraction of waveform characteristics, or “features,” and minimizing the error between features produced by TPA and ions. Modifying optical parameters can directly impact the waveform features of the TPA-induced transients. Consequently, optimal laser parameters that minimize the error between features extracted for laser- and ion-induced waveforms can be determined. In this paper, the laser pulse energy and spot size were varied, while maintaining a fixed pulse duration and wavelength, and the resulting transients were compared to ion-induced transients. When the optimized optical parameters are used, excellent agreement was achieved between laser- and ion-induced transient waveforms in a silicon-germanium heterojunction bipolar transistor (SiGe HBT). In addition, a one-to-one correlation between heavy-ion linear energy transfer (LET) and laser pulse energy was obtained for a particular spot size ($\omega _{0} = 1.89\,\,\mu \text{m}$ (HW $1/e^{2}$)). These results show that a correlation between LET and pulse energy is achievable when the remaining optical parameters are selected appropriately. Although the results presented are for SiGe HBTs, the generality of the approach should allow it to be extended to other semiconductor platforms. [ABSTRACT FROM AUTHOR]

A newly developed laser-assisted process is presented, by which a selective additive metallization of injection-molded alumina ceramic substrates without additional additives is enabled. Alumina substrates were manufactured by ceramic injection molding (CIM) with subsequent debinding and sintering. The substrate surfaces are activated by laser patterning for subsequent electroless plating of the activated areas with copper, nickel, and gold. Three-dimensionally shaped ceramic interconnect devices are enabled by CIM combined with 3-D laser patterning. The conducting paths fabricated in this way are characterized and compared to conducting paths made by a laser-direct-structure technology on thermoplastics developed by the company LPKF Laser & Electronics AG (LPKF-laser direct structuring process). The obtained metal layer thickness with about $10~\mu \text{m}$ is similar to metal layer thickness on thermoplastic substrates. Obtained metal surface roughness on ceramic substrates of below $10~\mu \text{m}$ is even lower than on thermoplastics. The high adhesion of approximately 30 N mm $^{-2}$ combined with the low thermal expansion coefficient of the alumina substrate promises good reliability even under thermal load. [ABSTRACT FROM AUTHOR]

We report temperature dependent electrical transport properties of high mobility reduced graphene oxide (RGO) thin films fabricated by pulse laser deposition. The temperature dependent (5K–350K) four terminal electrical transport property measurements confirm variable range hopping and thermally activated transport mechanism of the charge carriers at low (5K–210K) and high temperature (210K–350K) regions, respectively. The calculated localization length, the density of states near the Fermi level (EF), hopping energy, and Arrhenius energy gap provide useful information to explain the excellent electrical properties of the RGO films. Hall mobility measurement confirms p-type characteristics of the thin films. The charge carrier Hall mobility can be engineered by tuning the growth parameters, and the measured maximum mobility was 1596 cm2v−1s−1. The optimization of the improved electrical property is well supported by structural properties such as the defect density, average size of sp2 clusters and degree of reduction, which were investigated by Raman spectroscopy and X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

In this paper, multiferroic heterostructures have been prepared by growing MnZn ferrite films on ferroelectric single substrates using pulsed laser deposition technology. An enhanced magnetoelectric coupling has been achieved at the critical two-magnon scattering (TMS) angles, where the ferromagnetic resonance field shifts −653 and 211 Oe. The contribution of TMS effects is much larger than that of the conventional strain effect. This heterostructure provides an alternative route for novel integrated multiferroic materials and devices. [ABSTRACT FROM AUTHOR]

Mn ${_{1-x}}$ ZnxFe2O4 ($0.1\le x\le 0.8$) thin films with nanocrystalline grains were deposited on amorphous quartz substrate using pulsed laser ablation technique, at a substrate temperature of 650 °C. For $x\le 0.3$ , the room temperature spontaneous magnetization ($4\pi M_{S}$) of thin films was observed to be lower than the bulk composition. For $x=0.7$ , the room temperature $4\pi M_{S}$ value (~6.1 kG) is 7.5 times the bulk value for same x. This value is only 1.4 times of the bulk at 10 K, signifying a large enhancement in the exchange constant for thin films. The exchange stiffness constant (D) values were evaluated by fitting the $4\pi M_{S}$ data to the Bloch equation. The D values of thin films were always higher than that of the bulk. This result can be explained on the basis of occupancy of nonmagnetic Zn2+ on both the tetrahedral (A) and octahedral (B) sites. This is unlike in the bulk, where all the Zn2+ ions occupy only A site. [ABSTRACT FROM AUTHOR]

35 Bi(Mg1/2Ti1/2)O3-65 PbTiO3 (35 BiMT-65 PT) thin films with varying levels of A-site deficiency were investigated as a potential candidate for high-temperature nonvolatile ferroelectric memories. PbTiO3 seed layers utilized to nucleate the perovskite phase in A-site deficient films induced a thickness dependence to the ferroelectric hysteresis and dielectric permittivity. Adjusting for this, the dielectric response of the 35 BiMT-65 PT films is $\approx 960$. The maximum dielectric permittivity was 430 °C at 1 MHz for A-site deficient films. The transition temperature is independent of film thickness to 85 nm. Tan($\delta$) remains less than 15% at 1 MHz regardless of film thickness and temperature up to 585 °C. High-temperature polarization–electric field hysteresis measurements show charge injection with increasing temperature, while positive-up-negative-down measurements show little temperature dependence of $P_{r}$ up to temperatures of 200 °C. Poole–Frenkel emission dominated the high field leakage behavior. The refractive index measured by ellipsometry is 2.58 at 633 nm. All samples show significant retention loss. As the stoichiometry improves, retention improves such that >40% of the initial $\Delta P$ is retained over $\approx 280$ min. [ABSTRACT FROM AUTHOR]

35 Bi(Mg1/2Ti1/2)O3 - 65 PbTiO3 (35 BiMT-65 PT) is a potential candidate material for a high-temperature nonvolatile ferroelectric memory. For pulsed-laser deposited 35 BiMT-65 PT films with the perovskite structure, it was found that as the chamber pressure during deposition decreased, the Mg and Pb contents in as-deposited films drop, while the concentration of Bi increases. Concurrently with the change in composition, the remanent polarization $P_{r}$ increases 64% to $\approx 21~\mu \text{C}$ /cm2 and the polarization–electric field loops rotated counterclockwise as the deposition pressure increases. Decreasing the seed layer thickness from 36 to 16 nm led to a decrease in $P_{r}$ to $\approx 14~\mu \text{C}$ /cm2. Adjusting the target composition allowed the deposition of films which had near-stoichiometric Bi and Mg concentrations, but in all cases, the grown films were lead deficient. These films had remanent polarizations of 18– $20~\mu \text{C}$ /cm2. If the lead content of the target was increased too far, the remanent polarization decreased, possibly due to the need to evolve more PbO from defective growth layers. Finally, the deposition rate showed no substantial effect on the film composition, but did have a significant impact on the ferroelectric properties. As the deposition rate decreased, the $P_{r}$ increased to $\approx 22~\mu \text{C}$ /cm2 due to enhanced crystalline quality. At laser frequencies of 5 Hz, a Mg-rich pyrochlore phase begins to form and films showed a maximum $P_{r} \approx 22~\mu \text{C}$ /cm2. The processing-composition behavior is explained via preferential adsorption of Bi on the A-site, which results in lead vacancies. [ABSTRACT FROM AUTHOR]

Using a laser-equivalent linear energy transfer (LET) approach, strong correlation is found for collected charge following heavy-ion and pulsed-laser excitation in a bulk diode device. By significantly modifying the size of the charge distribution generated by one- and two-photon absorption compared to the depth of the sensitive region, charge deposition in a large variety of device technologies is mimicked. Nearly one-to-one correlation is found with heavy-ion charge collection, independent of the laser focusing geometry or magnitude of LET. Finally, this approach is applied to the previous studies where empirical laser-ion correlations on highly scaled technologies were proposed. These correlations are reproduced through direct calculation of the laser-equivalent LET, and outstanding observations are explained despite the sensitive areas of these devices being up to 1000 times smaller than the laser-deposited charge profile. In total, these studies suggest that this quantitative methodology for laser-ion correlation is broadly applicable for a range of complex device technologies. [ABSTRACT FROM AUTHOR]

This paper is dedicated to the investigation of single-event effects (SEEs) in different types of silicon Schottky diodes using heavy ions and laser pulses. The objectives are both to progress in heavy ions and laser correlations using simple devices and to further understand the impact of optical and electrical parameters on photogeneration in Schottky diodes to contribute to the use of pulsed lasers for single-event sensitivity studies. Heavy ion test results on planar and trenched commercial Schottky diodes are presented. Based on these results, pulsed laser tests and transient measurements were performed on the sensitive devices. Destructive single events were evidenced with both techniques. Significant parameters of the laser tests, such as backside aperture of the device, electrical and optical configuration are discussed. These investigations show the potential of laser testing for Schottky diode SEE sensitivity study. [ABSTRACT FROM AUTHOR]

We have already prepared a thin permanent magnet with the thickness of sub-millimeter by obtaining magnet powders using a pulsed laser deposition (PLD) method. In the article, the PLD followed by a flash annealing enabled us to deposit isotropic Pr–Fe–B magnet powders with coercivity $(H_{\mathrm {cj}})> 1000$ kA/m on a stainless thin shaft applicable to a miniaturized motor. Observation on the surface of Pr–Fe–B magnets and evaluation on the mechanical behavior were carried out. Since the surface of a Pr–Fe–B magnet was coated by a Pr oxide through an annealing process, their magnetic properties did not degrade after one year. We also confirmed that the Pr–Fe–B magnet has the possibility to be applied to a micro-magnetization process. It was clarified that the powder technology using the PLD is useful to propose a thin magnet applicable to a next-generation small motor. [ABSTRACT FROM AUTHOR]

REBabCu3Oy (REBCO, RE = rare earth) coated conductors are required for high current carrying capability. Selforganization of Ba-M-O (BMO, M = Zr, Sn, Hf …) is available to improve critical current density (Jc ) in magnetic field, and suppression of a-axis grain growth contributes to enhance Jc. The former and latter are affected by the surface diffusion of adatoms and supersaturation in the REBCO film growth, respectively. We focused on surface morphologies of SmBa2Cu3Oy (SmBCO) films deposited by the pulsed laser deposition method in this paper, and estimated surface diffusion constant and supersaturation from the surface morphologies. As a result, an activation energy of the surface diffusion was approximately 2.2 eV and the value is somewhat smaller than 2.5 eV for YBCO films. Additionally, we found that a-axis grains appeared when supersaturation (Δμ) became higher than a thresholdΔμ. Interestingly, a seed layer consisting of c-axis oriented SmBCO suppressed a-axis grain growth. These findings are useful to improve Jc in REBCO coated conductors. [ABSTRACT FROM AUTHOR]

The critical current Ic(B) of YBa2Cu3O7-δ (YBCO) coated conductors can be increased by growing thicker superconductor layers as well as improving the critical current density Jc(B) by the incorporation of artificial pinning centers. We studied the properties of pulsed laser deposited BaHfO3 (BHO)-doped YBCO films with thicknesses of up to 5 μm on buffered rolling-assisted biaxially textured Ni-5 at%Wtape and alternating beam assisted deposition textured Yttrium-stabilized ZrO2 layers on stainless steel. X-Ray diffraction confirms the epitaxial growth of the superconductor on the buffered metallic template. BHO additions reduce the film porosity and lower the probability to grow misoriented grains, hence preventing the Jc decrease observed in undoped YBCO films with thicknesses >2 μm. Thereby, a continuous increase in Ic at 77 K is achieved. A mixed structure of secondary phase nanorods and platelets with different orientations increases Jc(B) in the full angular range and simultaneously lowers the Jc anisotropy compared to pristine YBCO. [ABSTRACT FROM AUTHOR]

Fujikura Ltd., Chiba, Japan, has developed stable and high-throughput production techniques for REBCO coated conductors (CC) by using large-area ion-beam-assisted-deposition (IBAD), and hot-wall type pulsed-laser-deposition (PLD). Recently, we have been attempting to dope BaMO3 (BMO, M: Zr or Hf) to REBCO layer in order to enhance in-field critical current density (Jc ). In the course of optimizing deposition conditions of PLD for BaHfO3 doped EuBCO films on IBAD templates, "high Jc condition" and "high growth rate condition" were found. For samples prepared under these conditions, the magnetic field angle dependence of Ic and REBCO thickness dependence were investigated. Finally, we succeeded in fabricating a 300-m-long CC with uniform Ic distribution at the high-growth-rate condition. The longitudinal Ic homogeneity (defined as standard deviation divided by average) at 77 K evaluated by magnetization method was 2.6%, which is comparable to nondoped conductors. Transport in-field Ic for the both end points were 1756 and 1786 A/cm at 30 K, 2 T, respectively. [ABSTRACT FROM AUTHOR]

We have investigated the in-field critical current properties in BaZrO3-added (Y, Gd) Ba2Cu3O7-δ (YGdBCO)-coated conductor fabricated by using a multi-coating trifluoroacetates metal-organic deposition (MOD) method. We compared these properties with EuBCO-coated conductor fabricated by the pulsed laser deposition (PLD) method. The sample using the 30-nm oncecoat-layer-thickness donce shows superior in-field Jc down to 4.2 K than that of the previous standard coating using 170-nm-thick layer for each coating. From the analysis of E-J characteristics, an analytical expression for Jc as a function T and B has been derived. It was confirmed that the high Jc region in sample with donce = 30 nm is widely spread in high-temperature and high-magneticfield region. By comparison with the Jc properties of the BaHfO3 - added PLD CCs, the minimum Jc, which is estimated from magnetic field angle dependence, shows even higher value up to 5 T of magnetic field at 65 K and up to 3 T at 77 K. From these results, the new MOD-YGdBCO process using the thin once-coat-layerthickness is very promising for the practically important mid field region such as 3 to 5 T. [ABSTRACT FROM AUTHOR]

In this paper, boron-doped indium--zinc--oxide (InZnO) thin-film transistors (BIZO TFTs) were fabricated by solution process. The electrical performance and stability under the negative bias illumination stress (NBIS) have been greatly improved by B doping. The BIZO TFT with 5 mol.% B doping ratio shows a superior electrical performance with a field-effect mobility of 10.15 cm²/V · s, a threshold voltage of 3.29 V, a subthreshold swing of 0.35 V/decade, and an ON/OFF ratio of 108. Furthermore, the 5mol.% BIZO TFT shows only a-1.59V shift of the threshold voltage, compared with a large negative shift of -4.24 V for pure IZO TFTs. The enhancement of electrical performance and stability under NBIS is due to the reduction of oxygen vacancies, which are suppressed by B doping. The density of states is calculated to further validate the improved electrical performance and NBIS stability of BIZO TFTs. [ABSTRACT FROM AUTHOR]

Ex situ low-temperature (LT)-AlN templates are employed to realize GaN-based light-emitting diodes (LEDs) on Si substrates by the combination of pulsed laser deposition and metal organic chemical vapor deposition. The influence of ex situ LT-AlN template thickness on the properties and performance of as-grown LEDs has been carefully studied. The LED wafer grown on 70-nm-thick ex situ LT-AlN template exhibits a crack-free surface, good crystalline quality, and excellent multiple quantum wells (MQWs) structural property. The 500 × 500 μm2 LED chips fabricated with lateral structure show the highest light output power of 70.2 mW at an injection current of 300 mA. Through optimizing the thickness of ex situ LT-AlN template, the light output power is greatly improved by 39%. Theoretical analysis has been taken to study the enhancement mechanism of luminous intensity in this LED. It reveals that the residual stress in as-grown wafers is significant to enhance the luminescence of LEDs. The largest residual tensile stress in the LED presents great potential to enhance the carrier injection and transportation, increase the carrier concentrations, and improve the radiative recombination intensity in MQWs, which is crucial to improve the luminous intensity of LEDs. [ABSTRACT FROM PUBLISHER]

Studies have been carried out on the enhancement of responsivity and detectivity of the ZnO thin-films-based ultraviolet photodetectors by introducing an AlN buffer layer on silicon substrate. The ZnO film grown with AlN buffer layer established an epitaxial relation with the substrate and was found to show improved crystallinity with excellent optical properties. A strong and narrow photoluminescence emission was observed on the ZnO film grown with buffer layer, while a defect related broad emission was dominated on the film without buffer layer. The photodetectors showed a higher responsivity ( R\lambda ) of 1.03 \times 10^4 A/W with a specific detectivity ( D^\ast ) of 5.21 \times 10^12~ \text cm\cdot \text Hz^1/2\cdot \text W^\text -1 at an applied bias of 3 V due to their excellent crystal quality. [ABSTRACT FROM PUBLISHER]

To alleviate the mismatch between electron/hole velocities and improve the quantum efficiencies, the cobalt-doped ZnO (CZO) dilute magnetic films grown by pulsed-laser deposition at a low temperature of 100 °C were served as the external electron retarding n-electrodes for vertical InGaN light-emitting diodes (LEDs). The retardation of the electron mobility is owing to the scatter of electrons via the spin-orbit interaction of Co2+ ions and their corresponding ferromagnetic properties. A 150-nm-thick CZO film was chosen as the n-electrode for the vertical green LED (530 nm). In comparison to conventional lateral LED, the vertical LEDs without and with the CZO n-electrode had 21.3% and 39.6% improvements in the output power (at 350 mA), respectively. The vertical LED with the CZO n-electrode showed an increment in the light output power (at 350 mA) by 15.1% as compared with the vertical LED without the CZO n-electrode. Obviously, after inserting the CZO n-electrode, the excessively large mobility difference between the electron and hole carriers in the conventional vertical LED is reduced significantly, which can decrease the nonradiative recombination rate and improve the emission characteristic. The results also reveal the CZO film served as an external electron retarding electrode is highly potential for vertical LED applications. [ABSTRACT FROM PUBLISHER]

A tunable wavelength laser system and high-resolution transient capture system are introduced to characterize transients in high-mobility MOSFETs. The experimental configuration enables resolution of fast transient signals and new understanding of charge collection mechanisms. The channel layer is critical in the charge collection process for the InGaAs FinFETs examined here. The transient current mainly comes from the channel current, due to shunt effects and parasitic bipolar effects, instead of the junction collection. The charge amplification factor is found to be as high as 14, which makes this technology relatively sensitive to transient radiation. The peak current is inversely proportional to the device gate length. Simulations show that the parasitic bipolar effect is due to source-to-channel barrier lowering caused by hole accumulation in the source and channel. Charge deposited in the channel causes prompt current, while charge deposited below the channel causes delayed and slow current. [ABSTRACT FROM PUBLISHER]

Properties of NbN and TaxN thin films grown at ambient temperatures on SiO2/Si substrates by reactive-pulsed laser deposition and reactive magnetron sputtering (MS) as a function of N2 gas flow were investigated. Both techniques produced films with smooth surfaces, where the surface roughness did not depend on the N2 gas flow during growth. High crystalline quality, (111) oriented NbN films with Tc up to 11 K were produced by both techniques for N contents near 50%. The low temperature transport properties of the TaxN films depended upon both the N2 partial pressure used during growth and the film thickness. The root mean square surface roughness of TaxN films grown by MS increased as the film thickness decreased down to 10 nm. [ABSTRACT FROM PUBLISHER]

This correspondence comments on the correlation between measured and simulated charge collection in two diode structures presented in [1]. In [1], results from pulsed-laser-induced charge deposition via two-photon absorption revealed reasonable correlation between experimental data and simulations in some aspects but showed lack of correlation in terms of the measured and predicted magnitudes of the collected charge. The source of this poor agreement has recently been determined, and is attributed to an incorrect pulse energy calibration used for those experiments. With the proper energy calibration applied, the agreement between simulation and experiment is nearly quantitative for all observables in both devices. These results significantly strengthen the validity of the nonlinear optical beam propagation method numerical approach for accurately predicting pulsed-laser-induced charge deposition. [ABSTRACT FROM PUBLISHER]

Pr–Fe–B thick-film magnets were deposited on glass substrates without a buffer layer using a pulsed laser deposition method to apply the films to micro-electro-mechanical systems. Large particles with the average diameter of approximately 50~\mu \textm were emitted from a target and enabled us to obtain the relatively high deposition rate of 30~\mu \textm /h. An approximately 100~\mu \textm -thick Pr–Fe–B film with the (BH)\text {max} value of 70 kJ/ \textm^3 could be obtained. After polishing a Pr–Fe–B thick film deposited on a glass substrate with groove, the magnetic properties of the film did not deteriorate. [ABSTRACT FROM PUBLISHER]

Laser additive manufacturing has gained widespread adoption in recent years. However, process diagnosis and process control lag behind the progresses of other key technologies, which make the product quality control a challenging problem. This work proposes an operating parameter conditioned support vector regression (SVR) method that uses processing parameter conditioned kernel function to achieve a processing parameter independent in-situ composition prediction. Two different features of laser-induced plasma, spectral line-intensity-ratio, and both spectral line-intensity-ratio and spectral integrated intensity were used to train the SVR. Composition measurements using a calibration curve method, partial least square regression, and artificial neural networks are also performed for comparison. The results show that the SVR with both spectral line-intensity-ratio and spectral integrated intensity as inputs has the best performance due to linearly separable point clusters in the high-dimensional space. Laser power independent composition prediction is achieved and real-time composition predictions are validated. It is proved that the operating parameter conditioned SVR provides a more accurate, a more universal, and an operating parameter independent prediction. Moreover, operating parameter conditioned SVR provides a potential data-driven-based approach for real-time composition monitoring of the laser additive manufacturing process. [ABSTRACT FROM PUBLISHER]

The impact of semiconductor process scaling on the overall transient response of SiGe BiCMOS platforms is investigated. Pulsed-laser two-photon absorption (TPA) and heavy-ion broad-beam testing of SiGe HBT device and digital test structures across several generations of SiGe technologies are utilized to investigate the potential impacts of semiconductor process scaling (e.g., lateral/vertical scaling, changes in doping, Ge content, etc.) on the overall transient shape, magnitude, and duration. Technology scaling is shown to increase the single-event effect (SEE) sensitivity of SiGe HBTs (i.e., elevated collected charge, where 1st Gen. QC <3 rd Gen. QC <4 th Gen. QC ). Modern third-generation and fourth-generation devices under a forward-active bias (i.e., forward-biased EB junction, reverse-biased CB junction) exhibit a large diffusive transient component between the emitter and collector terminals, driving an elevation in collected charge. 3-D TCAD modeling is utilized to understand the fundamental transient mechanisms and assess the primary scaling factors affecting SEE sensitivity. Ion-strike simulations show that bulk traps can substantially enhance the charge collection mechanisms within these devices. These results suggest that SiGe technology scaling may have a strong impact on the radiation-induced transient response of SiGe HBTs, with future SiGe technology generations potentially exhibiting increased sensitivities to single-event effects. [ABSTRACT FROM PUBLISHER]

Amorphous InAlZnO (a-IAZO) films were grown by pulsed laser deposition at room temperature and annealed at various temperatures. The amorphous state of a-IAZO films is thermally stable at high temperatures up to 700 °C. The films exhibit a high visible transmittance above 95% and an appropriate resistivity on the order of 10^6~\Omega \cdot \text cm . As the annealing temperature increases, the optical bandgap and resistivity decrease in general. The microcracks form in films at an annealing temperature above 500 °C. The a-IAZO films annealed at 400 °C are suitable for channel layers of thin-film transistors (TFTs) and the devices demonstrate good performances with an on/off ratio of 10^8 and field-effect mobility of 2.2 \text cm^2\cdot \text V^-1\cdot \text s^-1 . The observations will provide useful physical insight into film properties and also offer basic design guideline for a-IAZO TFTs. [ABSTRACT FROM AUTHOR]

The strain dependence of critical current $(I_c)$ on BHO-doped GdBCO-coated conductors (CCs) was evaluated at 77 K in the self-field. The peak strain of $I_c$ for the BHO-doped GdBCO CCs shifted toward the compressive strain when compared to the pure-GdBCO CC, and the strain sensitivity of $I_c$ in the BHO-doped GdBCO CCs decreased with increasing BHO doping level. To clarify the difference between the strain sensitivity of $I_c$ and the peak strain of $I_c$ among the CCs, we measured the in-plane lattice parameters of GdBCO layers under tensile loading and estimated the internal lattice strain and the residual strain. As a result, the applied strain dependencies with the internal lattice strain and residual strain were almost the same, in spite of the different BHO doping level. This suggests that the change of the peak strain and the strain sensitivity were not related to the internal lattice strain. [ABSTRACT FROM PUBLISHER]

A 2-D time-dependent magnetohydrodynamic model of an ablation-dominated capillary is developed. The capillary discharge test is carried out to verify the validity of the numerical model. Special attention is paid to the radial distribution of the capillary discharge plasma characteristics. In addition, the factors that influence the radial distribution are investigated. Then, the competition of the ablation and deposition process with time in the capillary discharge is discussed. The results show that radial distributions of plasma characteristics are significant and influenced by the ablation rate. Three stages of the capillary discharge are observed, and the shorter rise time of the charging current would lead to a more uniform radial distribution of plasma temperature. [ABSTRACT FROM PUBLISHER]

The significant thermal stability improvement induced by laser annealing (LA) is demonstrated for 50-Å Ni(Pt) film silicidation. For the first time, it is revealed that LA may induce less stress in ultrathin Ni(Pt)Si film during silicidation, which can directly improve the thermal stability of the film. The local area annealing model is proposed to discuss the origin of stress relief. Besides, it is discovered that LA can result in a higher Pt concentration at the Ni(Pt)Si film surface, which will also enhance the resistance of Ni(Pt)Si film agglomeration. [ABSTRACT FROM AUTHOR]

Zinc ferrite films were deposited on fused quartz substrate at different substrate temperatures using a pulsed laser deposition technique. The deposited samples were ex situ annealed at different temperatures up to 650 °C in air for 2 h. It was found that the spontaneous magnetization of the films depends both on the grain size and on the substrate temperatures. The largest values of spontaneous magnetization for our sample were 3000 G at 300 K and 6600 G at 10 K, for the film deposited at substrate temperature of 450 °C. The ferromagnetic resonance linewidths of the films were found to depend both on substrate and annealing temperatures. A relatively low linewidth of 195 Oe was observed in parallel configuration for the film deposited at 250 °C and annealed at 350 °C. [ABSTRACT FROM AUTHOR]

Y3Fe5O12 thin films with thickness 10 10~nm \le t \le 1440 nm were grown on Gd3Ga5O12 (111) substrates by pulsed laser deposition. The X-ray diffraction experiments confirmed the films are pure yttrium iron garnet (YIG) phase with preferred (111) orientation. The magnetic and microwave properties were studied as a function of film thickness by the dc magnetization and ferromagnetic resonance (FMR) measurements. The FMR linewidth ( \Delta H ) was found to decrease with the increase in film thickness 10~{\rm nm} \le t \le 45 nm), attaining a minimum value of \Delta H_{\bot }=5 Oe and \Delta H\mathrm {\vert \vert }=6 Oe, for perpendicular and parallel resonance, and then rising with further increase in thickness. Acid etching experiments were performed to understand the mechanism contributing to \Delta H . The increase in $\Delta H$ with thickness ( $t > 45$ nm) may be explained in terms of extrinsic mechanisms, such as inhomogeneities present at the surface of the films. However, the decrease in $\Delta H$ with thickness ( $t < 45$ nm) is believed to be due to the surface anisotropy effect. The films showed low coercivity values in the range of $\sim 1.5$ –7 Oe, which is an indicator of good quality YIG films. [ABSTRACT FROM AUTHOR]

Air-core Tesla transformer combined with semiconductor devices can generate repetitive high-voltage pulses effectively. Air-core Tesla transformer of spiral type is suitable for repetitive operation since its primary voltage is relatively low. Based on the double resonance circuit of air-core Tesla transformer, the expressions of secondary voltage, primary current, and the maximum rise-rate of primary current are deduced. The effects of tuning characteristic on the output voltage and energy efficiency are simulated, and further verified by experiments. An air-core Tesla transformer prototype of spiral type is developed. To achieve repetitive operation, a resonant charging and discharging circuit based on air-core Tesla transformer is designed. The repetitive system based on this prototype can generate microsecond pulses with an average peak voltage of -140 kV at 300 Hz repetition rate. In repetitive mode, the tuning ratio is recommended to range in 1.0-2.0 to achieve high energy efficiency. The output voltage could be higher by increasing the charging voltage or tuning ratio. [ABSTRACT FROM PUBLISHER]

In this contribution, we report on the compositional dependence of the mechanical and piezoelectric properties of Pb(ZrxTi1-x)O3 (PZT) thin films fabricated by pulsed laser deposition (PLD). These films grow epitaxially on silicon with a (110) preferred orientation and have excellent piezoelectric properties, which make them outstanding candidates for application in microelectromechanical system devices. Vibrometric measurements on capacitors showed that the effective longitudinal piezoelectric coefficient (d33,f) of 100-nm thick PZT films has a maximum value of 72 pm/V for a composition of x = 0.52. The Young's modulus was determined by measuring the difference in the flexural resonance frequencies of cantilevers before and after the deposition of the PZT thin films. The compositional dependence of the Young's modulus shows an increase in value for the Zr-rich compositions, which is in agreement with the trend observed in their bulk ceramic counterparts. From the obtained dielectric constant and d33,f, we show that the calculated coupling coefficients of the PLD-PZT thin films have higher values for most of the compositions than their ceramic counterparts. [ABSTRACT FROM AUTHOR]