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Excess minority carriers create boron-related recombination centers that degrade the efficiency of the non-particle-irradiated silicon solar cells. However, the carrier-induced reactions among the radiation-induced defects are poorly understood for devices exposed to particle radiation. This study investigates the structure, electronic properties, formation and annihilation mechanisms, and diffusion dynamics of the carrier-induced defects in particle-irradiated boron-doped silicon using density-functional modeling and junction spectroscopy. By revisiting the ground-state structures of the boron-di-interstitial clusters (B I 2), we find that the calculated acceptor and donor levels of such defects agree well quantitatively with the carrier-induced deep-level transient spectroscopy (DLTS) hole emission signatures at 0.43 and 0.53 eV above the valence band edge (E v), respectively. We also find that the formation of B I 2 is thermally activated by an energy of 0.50 eV, which we explain theoretically by the reduction of the migration barrier of mono-interstitials to 0.53 eV in the presence of excess minority carriers. Moreover, we discover that the B I 2 are potentially mobile with a migration barrier of 1.18 eV, contrary to the present understanding. [ABSTRACT FROM AUTHOR]

Scanning near-field optical microscopy is one of the most effective techniques for spectroscopy of nanoscale systems. However, inferring optical constants from the measured near-field signal can be challenging because of a complicated and highly nonlinear interaction between the scanned probe and the sample. Conventional fitting methods applied to this problem often suffer from the lack of convergence or require human intervention. Here, we develop an alternative approach where the optical parameter extraction is automated by a deep learning network. The network provides an initial estimate that is subsequently refined by a traditional fitting algorithm. We show that this method demonstrates superior accuracy, stability against noise, and computational speed when applied to simulated near-field spectra. [ABSTRACT FROM AUTHOR]

This study examines the electronic and luminescent properties of β-(AlxGa1−x)2O3 (0 ≤ x ≤ 0.42) thin films grown on (0001) sapphire using laser-MBE, with a focus on the evolution of defect energy levels and their impact on surface Fermi level pinning and luminescence. X-ray photoelectron spectroscopy (XPS) and cathodoluminescence (CL) have been employed to analyze surface band bending and defect evolution as a function of aluminum content. The results have revealed a pinned Fermi level at 3.6 eV above the valence band maximum despite the increase in the bandgap. The consequent upward band bending has been confirmed by a peak shift in the core level XPS. The defects that lead to the Fermi level pinning effect are attributed to E2*, which is related to a Ga vacancy or Ga vacancy-O vacancy complex. In addition, CL spectroscopy and depth-resolved CL have demonstrated consistent blue and ultraviolet emissions across the Al content range and a similar suppression of electron concentration on blue and ultraviolet emissions in β-(AlxGa1−x)2O3 and β-Ga2O3. Based on the observed evolution of defects with Al content, the blue band emission is attributed to electron transition in the donor–accepter pair. [ABSTRACT FROM AUTHOR]

This study examines the electronic and luminescent properties of β-(AlxGa1−x)2O3 (0 ≤ x ≤ 0.42) thin films grown on (0001) sapphire using laser-MBE, with a focus on the evolution of defect energy levels and their impact on surface Fermi level pinning and luminescence. X-ray photoelectron spectroscopy (XPS) and cathodoluminescence (CL) have been employed to analyze surface band bending and defect evolution as a function of aluminum content. The results have revealed a pinned Fermi level at 3.6 eV above the valence band maximum despite the increase in the bandgap. The consequent upward band bending has been confirmed by a peak shift in the core level XPS. The defects that lead to the Fermi level pinning effect are attributed to E2*, which is related to a Ga vacancy or Ga vacancy-O vacancy complex. In addition, CL spectroscopy and depth-resolved CL have demonstrated consistent blue and ultraviolet emissions across the Al content range and a similar suppression of electron concentration on blue and ultraviolet emissions in β-(AlxGa1−x)2O3 and β-Ga2O3. Based on the observed evolution of defects with Al content, the blue band emission is attributed to electron transition in the donor–accepter pair. [ABSTRACT FROM AUTHOR]

An E-band (60–90 GHz) multi-channel Doppler backscattering (DBS) system with X-mode polarization has been installed on the Experimental Advanced Superconducting Tokamak (EAST), which can measure the turbulence at five different radial locations simultaneously. This system can launch 31 fixed microwave frequencies in the range of 60–90 GHz with a 1 GHz interval into the plasma, and five probing signals are selected by employing a reference signal and multiple filters. During experiments, the frequency of the reference signal is tunable in the E-band, and the selected probing signals can be changed as needed without any other adjustments, which can be performed in one shot or between shots. Furthermore, the incident angle can be adjusted from −10° to 20°, and the wavenumber range is 4–25 cm−1 with a wavenumber resolution of Δk/k ≤ 0.35. Ray tracing simulations are employed to calculate the scattering locations and the perpendicular wavenumber. In this article, the hardware design, ray tracing, and initial results obtained from the EAST plasma will be presented. [ABSTRACT FROM AUTHOR]

In the present work, the distortion modes and ferroelectric properties of Sr3(Sn1−xZrx)2O7 (x = 0.0, 0.25, 0.5, 0.75, 1.0) ceramics with double-layered Ruddlesden–Popper structures were investigated. The amplitudes of three distortion modes for the ferroelectric phase deviated from the aristotype one were quantified using the symmetry-mode approach adopted in Rietveld refinement against x-ray diffraction patterns. The remanent polarization and the coercive field decreased with increasing the content of Zr4+ cations. The decline of polarization should attribute to the nonpolar secondary phase, while the suppression of a coercive field may connect with the decreased amplitude of the rotation mode. The Curie temperatures increased linearly with increasing x value in Sr3(Sn1−xZrx)2O7 ceramics, inducing from the decline of a tolerance factor. A typical first-order improper ferroelectric phase transition was determined using a differential scanning calorimetry measurement and dielectric characterization. From the present work, a straightforward way to quantify the amplitude of a distortion mode for the ferroelectric phase was given, and the ferroelectric properties could be effectively tuned by substituting the cations at the B site in the Sr-based hybrid improper ferroelectrics. [ABSTRACT FROM AUTHOR]

We demonstrate that large apparent converse flexoelectric properties can be obtained in piezoelectric composites using theoretical approaches. To do so, we first present a numerical homogenization method accounting for all electromechanical terms related to strain and the electric field gradient. We then evaluate the coefficients of the model by numerical simulations on periodic piezoelectric composites. After combining the homogenization approach with topology optimization to enhance the converse properties of the composite, we present numerical results that reveal that the apparent converse flexoelectric coefficients, as well as those associated with the higher order coupling terms involving the electric field gradient, are of the same order as the direct flexoelectric properties of the local constituents. These results suggest that both converse and higher order electromechanical coupling effects may contribute strongly to the flexoelectric response and properties of piezoelectric composites. Finally, we show that it is theoretically possible to obtain optimized designs of composites with apparent converse flexoelectric properties 1–2 orders of magnitude larger than ones obtained with naïve guess designs. [ABSTRACT FROM AUTHOR]

Ca3Ti2O7 with a Ruddlesden–Popper structure has received great scientific attention due to its high ferroelectric polarization. However, the optimization of hybrid improper ferroelectricity is still a challenging issue. In the present work, the remarkably improved ferroelectric polarization has been achieved in B-site co-substituted Ca3Ti1.8Al0.1Nb0.1O7 ceramic. The improved ferroelectric polarization in this ceramic stems from the higher ferroelectric activity of Nb5+ cations and a larger amplitude of oxygen octahedral distortion. Moreover, the more saturated electric hysteresis loops together with the higher ferroelectric polarization can be achieved under a higher electric field and at a lower frequency. The first-order phase transition nature is proved by the thermal hysteresis, while the Curie temperature is directly proportioned to the tolerance factor. The present work provides an effective way to improve the ferroelectric properties without declining the Curie temperature in Ca3Ti2O7-based hybrid improper ferroelectricities. [ABSTRACT FROM AUTHOR]

Spin Hall magnetoresistance (SMR) provides a unique opportunity for the signal readout of magnetic ordering, especially for magnetic insulators. However, the magnitude of SMR signals is quite small, generally lower than one in a thousand, which is a persistent challenge in the field of spintronics. Here, we investigate SMR at room temperature in α-Fe2O3/Pt and γ-Fe2O3/Pt bilayers as well as the α-Fe2O3/Pt/γ-Fe2O3 trilayer, where α-Fe2O3 and γ-Fe2O3 are antiferromagnetic and ferrimagnetic materials, respectively. In contrast to the positive SMR in the γ-Fe2O3/Pt bilayer, an unprecedentedly large negative SMR with the magnitude of ∼0.35% is observed in the α-Fe2O3/Pt bilayer due to the spin-flop. The α-Fe2O3/Pt/γ-Fe2O3 trilayer shows features of a combination of positive and negative SMR. A comparative study of SMR in the Fe2O3 family not only enriches spin physics, but also makes Fe2O3 a versatile candidate in spintronic devices. [ABSTRACT FROM AUTHOR]

An analytical solution describing the electrostatic interaction between particles with inhomogeneous surface charge distributions has been developed. For particles, each carrying a single charge, the solution equates to the presence of a point charge residing on the surface, which makes it particularly suitable for investigating the Coulomb fission of doubly charged clusters close to the Rayleigh instability limit. For a series of six separate molecular dication clusters, center-of-mass kinetic energy releases have been extracted from experimental measurements of their kinetic energy spectra following Coulomb fission. These data have been compared with Coulomb energy barriers calculated from the electrostatic interaction energies given by this new solution. For systems with high dielectric permittivity, results from the point charge model provide a viable alternative to kinetic energy releases calculated on the assumption of a uniform distribution of surface charge. The equivalent physical picture for the clusters would be that of a trapped proton. For interacting particles with low dielectric permittivity, a uniform distribution of charge provides better agreement with the experimental results. [ABSTRACT FROM AUTHOR]

The large dark current increase near the breakdown voltage of an InGaAs/InP avalanche photodiode is observed and analyzed from the aspect of bulk defects in the device materials. The trap level information is extracted from the temperature-dependent electrical characteristics of the device and the low temperature photoluminescence spectrum of the materials. Simulation results with the extracted trap level taken into consideration show that the trap is in the InP multiplication layer and the trap assisted tunneling current induced by the trap is the main cause of the large dark current increase with the bias from the punch-through voltage to 95% breakdown voltage. [ABSTRACT FROM AUTHOR]

A 105 GHz/500 kW/1 s electron cyclotron resonance heating (ECRH) system has been developed on J-TEXT tokamak since 2017. The core component of the ECRH system is a gyrotron manufactured by Gyrotron Complexes Ltd. (GYCOM Ltd.), which generates microwaves of a certain frequency and power. To guarantee safe and stable operation, it is necessary to design a specialized control system. The control system is expected to perform time sequence trigger, protection, signal monitoring, communication, and data acquisition. The hardware is built with real-time processors and data acquisition modules from National Instruments. The control program is realized by LabVIEW. Test results indicate that the control system can commit stable and safe operation of the gyrotron, which guarantees the integrated commissioning tests of the whole ECRH system and ECRH related physics experiments. Under the operation of this control system, the gyrotron can generate microwaves as expected, and the ECRH system is well protected when a fault takes place. [ABSTRACT FROM AUTHOR]

The edge-harmonic oscillations (EHOs) in standard quiescent H-mode (QH-mode) plasmas in DIII-D are consistent with edge-localized neoclassical tearing modes (NTMs) based on nonlinear two-fluid MHD simulations. Using kinetic equilibria constrained by edge profile measurements, the MHD simulations show that the n = 1 NTM and its harmonics can be destabilized at the pedestal top of QH-mode plasma by the edge bootstrap current. The simulations further show that the unstable NTMs can saturate either at small (<2% ψN) or large (>4% ψN) island width depending on the magnitude of the edge bootstrap current, where ψN is the normalized radius in poloidal flux. The onset of the EHO also results in a prompt decrease in the pedestal width and height, consistent with simulation results for the onset of the NTM at the top of the QH-mode pedestal. This suggests that the avoidance of edge-localized modes (ELMs) in QH-mode can be attributed to the enhanced local transport induced by the NTM that is sufficient to prevent the expansion of the pedestal to an unstable width, analogous to the mechanism explored for ELM suppression by resonant magnetic perturbations. Nonlinear MHD simulations scanning the E × B frequency and the ratio of parallel and perpendicular thermal diffusivity (χǁ/χ⊥) at the pedestal top show that edge-localized NTMs are destabilized for conditions of high E × B frequency, high pedestal temperature, and low pedestal density, qualitatively consistent with experimental conditions required for observing the EHO. [ABSTRACT FROM AUTHOR]

The fluid tank is an essential facility for experimental research on fluid mechanics. However, owing to the hydrostatic fluid pressure, a fine uniformity of the narrow channel is difficult to be maintained in a tall narrow–channel tank. To address this issue, we proposed a quasi-two-dimensional fluid experimental apparatus based on a "tank-in-tank" configuration and built with an outer tank and an inner tank. The outer tank was cuboid-shaped and used to load the fluid medium, while the inner tank, consisting of two parallel glass plates, was embedded into the outer tank and served as the experimental channel. The hydrostatic pressure acting on the channel was balanced so that a high level of uniformity was maintained over the whole channel. The available height and width of the channel were 2800 and 1500 mm, respectively, while its gap distance could be adaptive from 0 to 120 mm. Experimental research on motion characteristics of circular disks falling in the quasi-2D channel was implemented to investigate the effects of the falling environment and disk geometry. Four distinct falling types were observed, and the wake flow fields of the falling disks were visualized. The Reynolds numbers of falling disks ranged from 400 to 63 000 presently. Chaotic motion and regular motion were demarcated at Re ≈ 30 000. An analytical model was established to predict the final average falling velocity and Reynolds number. Finally, potential directions for future research and improvements to the apparatus were suggested. [ABSTRACT FROM AUTHOR]

The field null configuration of a poloidal magnetic field is one of the critical conditions for achieving Ohmic breakdown during the initial discharge of a new tokamak. The issue of the Ohmic breakdown on the NanChang Spherical Tokamak (NCST) is still not solved satisfactorily although plasma currents of about 2 kA were found. Hence, a removable three-dimensional magnetic probe (RTMP) system consisting of 25 magnetic probes was designed, calibrated, and constructed on the NCST to evaluate the field null inside a vacuum vessel. After repeated tests, the RTMP system exhibited outstanding performance in terms of accuracy and stability with errors of about 1%. Meanwhile, the RTMP system successfully measured the toroidal field (TF) coil ripples at the magnetic axis. During experiments, the stray field arising from the TF coil implied a strong link between the flexible connection of the TF coil and the Ohmic breakdown on the NCST. After the field null was effectively modified by using a new flexible connection of the TF coil and controlling the induced current in the poloidal field coil, the NCST tokamak reproducibly obtained 20 kA plasma current with the limiter configuration during the plasma current flat-top phase. [ABSTRACT FROM AUTHOR]

The sample temperature in an externally heated diamond anvil cell (EHDAC) is generally measured by a thermocouple fixed to the pavilions of diamond anvils, ignoring the temperature difference between the thermocouple and the sample. However, the measured temperature depends strongly on the placement of the thermocouple, thus seriously reducing the accuracy of the temperature measurement and hindering the use of EHDAC in experiments requiring precise temperature measurements, such as high-pressure melting and phase-diagram investigations. In this study, the full width at half maximum (FWHM) of the 0–0 fluorescence line of strontium borate doped with bivalent samarium ions (SrBO4:Sm2+, SBO) is found to be highly sensitive to temperature and responds extremely rapidly to small temperature fluctuations, which makes it an excellent temperature indicator. We propose herein a precise method to measure temperature that involves measuring the FWHM of the 0–0 fluorescence line of SBO. This method is used to correct the temperature discrepancy between the thermocouple and the sample in an EHDAC. These corrections significantly improve the accuracy of temperature measurements in EHDACs. The accuracy of this method is verified by measuring the melting point of tin at ambient pressure. We also use this method to produce a tentative elementary phase diagram of tin up to 109 GPa and 495 K. This method facilitates high-pressure, high-temperature experiments demanding accurate temperature measurements in various disciplines. The study also discusses, in general, the experimental approach to measuring temperature. [ABSTRACT FROM AUTHOR]

The radiation effects of metal-oxide-semiconductor (MOS) capacitors based on an Al2O3 gate dielectric were studied using 30 MeV Si heavy ions. To give insights into the types of defects induced by Si ion irradiation in the gate oxide, synergistic experiments involving γ-ray irradiation and Si ion irradiation were carried out. The results revealed that the defects in the as-grown Al2O3 layer were found to be hole trapping centers, whereas Si ion induced new defects were electron trapping centers. The experimental and simulation data of current density-voltage (J-V) curves confirmed that the transmission mechanism of leakage current in the Al2O3 layer was mainly dominated by the Frenkel-Poole mechanism. In detail, the variations of leakage current were mainly due to the attributions of the local built-in electric field-assisted current leakage and the conductive path-assisted current leakage and were found to be dependent on the irradiation condition and Al2O3 thickness. Lastly, the decrease of the gate oxide capacitance of MOS capacitors was attributed to the increase of the series resistance and leakage current in MOS capacitors. [ABSTRACT FROM AUTHOR]

Hybrid improper ferroelectricity, which is induced by the coupling of oxygen octahedral rotation and tilt in oxide materials, has great potential to create single-phase multiferroic materials with intrinsic electric field-controlled magnetism. Based on previous experiments with bi-layered Ruddlesden-Popper Sr-based materials, hybrid improper ferroelectricity in Sr3Hf2O7 was investigated by first-principle calculations in the present work. The results show that the ferroelectric A21am phase has the lowest energy among all possible phases, indicating that it is the ground state. The spontaneous polarization calculated by the Berry phase approach and Born effective charge model is approximately 4.6 μC/cm2, in agreement with those reported for other Sr-based compounds. Compared to Ca3Ti2O7, the smaller polarization of Sr3Hf2O7 is attributed to the negative contribution of the HfO2 layer to global polarization. The possible ferroelectric switching path was determined using the nudged elastic band method. The energy barriers of the two four-step paths across the non-polar Pbnm and Pnab phases are almost the same, and they are the lowest energies among all possible paths. Competition between these paths can help us understand complex phase transitions in analogous compounds. In summary, hybrid improper ferroelectricity was predicted in Sr3Hf2O7 for the first time, and the possible ferroelectric switching paths were determined. [ABSTRACT FROM AUTHOR]

Hybrid improper ferroelectricity is induced by the coupling of oxygen octahedral rotation and tilt, and it may provide a promising way to develop new room-temperature single-phase multiferroic materials with a strong magnetoelectric effect. Though ferroelectric polarizations are confirmed by the electric hysteresis loops at room temperature, the ferroelectric-paraelectric phase transition has not been well understood. In the present work, the crystal structures, dielectric properties, and phase transition behaviors of Ruddlesden-Popper Sr3–xCaxSn2O7 ceramics are thoroughly determined. Ferroelectricity is confirmed through the polarization-electric field hysteresis loops at room temperature, and the Curie temperature is identified by the variable-temperature differential scanning calorimetric analysis and dielectric characterization. The polarizations and Curie temperatures of the present ceramics increase with increasing the calcium content. An improper ferroelectric transition is experimentally evidenced by a small dielectric constant and a step variation of dielectric constant around the Curie temperature, and the thermal hysteresis of dielectric constant confirms the first order transition nature. Moreover, the fitting result of Landau phase transition theory also suggests the first-order improper ferroelectric transition nature. The variable-temperature Raman result implies a tetragonal paraelectric phase above TC. The present work confidently confirms the first-order hybrid improper ferroelectric transitions in the present ceramics, and ferroelectric properties can be readily tuned by substituting the cations at the A-site. [ABSTRACT FROM AUTHOR]

In this work, we examine the swelling of nanostructured block copolymer electrolytes immersed in liquid water. A series of sulfonated polystyrene-b-polyethylene-b-polystyrene (S-SES) membranes having the same nominal chemical composition but two different morphologies are prepared by systematic changes in processing. We start with a membrane comprising a mixture of homopolymer polystyrene (hPS) and a polystyrene-b-polyethylene-b-polystyrene (SES) copolymer. hPS is subsequently selectively removed from the membrane and the polystyrene domains are sulfonated to give S-SES membranes. The morphology of the membranes is controlled by controlling ϕv, the volume fraction of hPS in the blended membrane. The morphology of the membranes was studied by small angle X-ray scattering (SAXS), cryogenic scanning transmission electron microscopy (cryo-STEM), and cryogenic electron tomography. The overall domain swelling measured by SAXS decreases slightly at ϕv = 0.29; a crossover from lamellar to bicontinuous morphology is obtained at the same value of ϕv. The bicontinuous morphologies absorb more water than the lamellar morphologies. By contrast, the nanodomain swelling of the bicontinuous membrane (120%) is slightly less than that of the lamellar membrane (150%). Quantitative analysis of the STEM images and electron tomography was used to determine the swelling on the hydrophilic and hydrophobic domains due to exposure to water. The hydrophilic sulfonated polystyrene-rich domain spacing increases while the hydrophobic polyethylene domain spacing decreases when the membranes are hydrated. The extent of increase and decrease is not a strong function of ϕv. [ABSTRACT FROM AUTHOR]

Millimeter wave systems based on powerful gyrotron can deliver megawatt microwave power, which is an important auxiliary heating method for magnetic confinement fusion devices. Reflective gratings are normally used as quasi-optical polarizers for polarization control of the wave in such systems. Based on the coordinate transformation method, we developed a numerical code to study the broadband polarization strategy. By considering the synthesis of two polarizers, we designed a pair of polarizers in the W band. Calculation results indicated that almost arbitrary polarization can be achieved in a wide frequency range. To verify the design, we set up a low-power test platform and experiments were carried out. The performance of the polarizers was tested from 80 to 105 GHz with a step of 5 GHz. The test results agreed well with the numerical results, indicating that the design is reasonable. With the development of multi-frequency gyrotrons, the study in this paper can be used as a reference for the design of broadband polarizers of multi-frequency millimeter wave systems. [ABSTRACT FROM AUTHOR]

The linear and the non-linear behaviors of the ion temperature gradient (ITG) mode in a plasma with regularized κ-distributed electrons are investigated using the fluid model. The dispersion relation of the ITG mode obtained on the basis of the local approximation shows that the growth rate of the ITG mode decreases with the increase in the spectral index κ and the exponential cut-off parameter α. It indicates that the presence of the superthermal electron leads to destabilization of the ITG mode, especially in the low κ (κ < 1.5) region. In addition, the existence and the nature of the soliton structure driven by the ITG are studied using the pseudopotential technology. The soliton amplitude increases with the increase in the exponential cut-off parameter α and the spectral index κ, whereas the width of the soliton varies inversely. The present results will help to understand the low-frequency electrostatic wave and nonlinear structure in space and experimental plasmas with non-thermal electrons. [ABSTRACT FROM AUTHOR]

Hybrid improper ferroelectricity (HIF) has been proposed as a candidate approach to create room- temperature multiferroic materials with an intrinsic electric-field controlled magnetism effect, and HIFs in bi-layered Ruddlesden-Popper Ca3-xSrxTi2O7 ceramics have been confirmed in the present work. The ferroelectric hysteresis loops are observed in these ceramics at room temperature, and the polar orthorhombic structures with oxygen octahedral rotation and tilt modes have been confirmed by room-temperature X-ray powder diffraction. The amplitudes of oxygen octahedral rotation and tilt modes decrease with the increasing x value, which in turn leads to the decrease of remnant polarization in these ceramics. A first-order phase transition has been evidenced by the differential scanning calorimetry measurement, and the temperature of phase transition decreases linearly with the increasing content of strontium cations. It is found that the amplitude of oxygen octahedral distortion is the dominating factor that affects ferroelectric polarization in partial-ordered bi-layered Ca3Ti2O7-based ceramics. [ABSTRACT FROM AUTHOR]

In the past, terahertz spectroscopy has mainly been performed based on terahertz time-domain spectroscopy systems in a transmission or a window/prism-supported reflection configuration. These conventional approaches have limitations in regard to characterizing opaque solids, conductive thin films, multiple-layer structures, and anisotropic materials. Ellipsometry is a self-reference characterization technique with a wide adaptability that can be applied for nearly all sample types. However, terahertz ellipsometry has not yet been widely applied, mainly due to the critical requirement it places on the optical setting and the large discrepancy with regard to traditional terahertz spectroscopy and conventional optical ellipsometry. In this Tutorial, we introduce terahertz time-domain spectroscopic ellipsometry from the basic concept, theory, optical configuration, error calibration to characterization methods. Experimental results on silicon wafers of different resistivities are presented as examples. This Tutorial provides key technical guidance and skills for accurate terahertz time-domain spectroscopic ellipsometry. [ABSTRACT FROM AUTHOR]

The NanChang Spherical Tokamak (NCST), a new compact (plasma major radius R = 0.40 m, minor radius a = 0.24 m, and aspect ratio A = 1.67) spherical tokamak, is suitable for teaching and scientific research activities at the university. The principal goal of the device is to initiate plasma currents by utilizing merging compression. At present, the NCST has a total of five complete coil systems, including the coils and their dedicated power supplies, to generate and control the plasma as per the experimental objectives. This paper presents the NCST device and its coils, the design of the power supplies, and the simulation results of plasma configurations as well as the comparison of experimental and simulation results of the above-mentioned power supply system. [ABSTRACT FROM AUTHOR]

Nanoparticles with different core@shell structures (NaGdF4:Yb/Tm@NaLnF4 with Ln=lanthanide) were successfully synthesized for luminescence upconversion from 980 nm to 800 nm. The upconversion luminescence of the core@shell nanoparticles (NaGdF4:Yb/Tm@NaGdF4) has a much stronger infrared emission centered at 800 nm than that of the core-only nanoparticles (NaGdF4:Yb/Tm). This is not only due to the removal of surface defects of the core nanoparticles by the shell, which results in the decrease of the luminescence quenching, but also due to the breaking of the crystal field symmetry around the Tm3+ ion. By replacing the NaGdF4 shell with an NaYF4, the emission could further be enhanced. We suggest that the breaking of the crystal field symmetry plays also in this case a key role for further enhancement of upconversion emission. The importance of this asymmetry was further revealed by investigating the energy transfer between Er3+ ion in the shell and the Tm3+ ion of the core nanoparticle. [ABSTRACT FROM AUTHOR]

Using comprehensive density functional theory calculations, the structural, electronic, and optical properties of novel fluorosilicene/chlorosilicene (F-silicene/Cl-silicene) heterobilayer are investigated. Our results unveil that the presence of hetero-halogen bonding (Si-F∙∙∙Cl-Si) has a remarkable influence on the F-silicene/Cl-silicene bilayer. The F-silicene/Cl-silicene heterostructure in the most stable pattern has a moderate band gap of 0.309 eV, lower than that of isolated halogenated silicene. Encouragingly, F-silicene/Cl-silicene heterobilayers all have a direct band gap nature, irrespective of the stacking pattern, thickness and external electric fields (E-fields), which is an advantage over MoS2 layers. In addition, applying appropriate E-field leads to a significant enhancement of binding strength of the F-silicene/Cl-silicene heterobilayer. Especially, the band gap of the F-silicene/Cl-silicene heterobilayer can be effectively modulated by E-fields, even a semiconductor-metal transition occurs. Moreover, the interfacial hetero-halogen interaction changes the optical properties of isolated halogenated silicene; the adsorption edge of imaginary part of the dielectric function displays a corresponding redshift in comparison with that of isolated halogenated silicene, which makes the F-silicene/Cl-silicene heterostructure active over the visible range. The complete electron-hole separation also enhances the photocatalytic efficiency of the F-silicene/Cl-silicene heterobilayer. Overall, the moderate band gap, effective band gap modification by external E-field, robust direct band gap nature, suitable band edge positions, and type-II band alignment enable the F-silicene/Cl-silicene heterobilayer to have great potential applications in the field of optical and nanoelectronic devices. [ABSTRACT FROM AUTHOR]

The NanChang Spherical Tokamak (NCST) is a new compact tokamak (with an aspect ratio of R/a = 1.67) for exploring the merging compression by which the plasma start-up is highly efficient. In this paper, a magnetic diagnostic system is designed, calibrated, and constructed on the NCST to meet the requirements of measurements. Based on detailed testing and analysis, the reliability of the sensors is guaranteed by optimizing the support structure and installation process. In addition, high-precision positioning equipment is utilized to ensure the installation accuracy of the sensors. During the start-up phase of the NCST, plasma currents on the order of a few kiloamperes were measured despite that the commensurate signal of eddy current is also found in the conducting structure. The magnetic diagnostic system is now completely operational and meets the requirements of the physical analysis on the NCST. [ABSTRACT FROM AUTHOR]

We report the bias-dependent tunneling anisotropic magnetoresistance (TAMR) in antiferromagnetic α′-Fe(Rh0.98Pd0.02)/MgO/γ-Fe(Rh0.98Pd0.02) junctions. The TAMR effect is driven by the antiferromagnetic-ferromagnetic phase transition of α′-Fe(Rh0.98Pd0.02) and concomitantly large variation of the density of states (DOS) near the Fermi level. It exhibits polarity reversion behavior with increasing bias voltage, i.e., negative and positive polarities for low and high bias voltages, respectively. Such bias-dependent TAMR is comprehended by first-principle calculations, where a crossing point and subsequent magnitude-reversion emerge between the DOS of antiferromagnetic and ferromagnetic phases of α′-Fe(Rh0.98Pd0.02). Harnessing the tunneling behavior by a feasible bias voltage in an antiferromagnet-based junction is a frontier of great promise in antiferromagnet spintronics. [ABSTRACT FROM AUTHOR]

Heteroepitaxy of corundum-structured α-Ga2O3 and intriguing ferroelectric κ-Ga2O3 is proven as an alternative strategy to solve current challenges in heat dissipation and large-scale productivity for Ga2O3-based power electronic devices, whereas the fundamental growth dynamics and phase control of metastable Ga2O3 are still far unexplored. In this Letter, we demonstrate the strategy of strain engineering for the in situ phase manipulation of metastable Ga2O3 by embedding α-In2O3 submicrometer dots. Phase transition is modulated by the surface coverage of α-In2O3 due to the competitive growth of κ-Ga2O3 upon α-In2O3 and the homoepitaxy of α-Ga2O3 on the exposed α-Ga2O3 seed region. Upon discrete α-In2O3 submicrometer dots with a low surface coverage, the growth undergoes a nano-scale epitaxial lateral overgrowth mode, in which the selective homoepitaxy of α-Ga2O3 is dominant, and embedded α-In2O3 serves as nano-masks to prevent the threading dislocation propagation into the lateral overgrown Ga2O3 layer. In comparison, κ-Ga2O3 is energetically favorable on the interconnected α-In2O3 submicrometer dots, which are driven by the in-plane tensile strain as probed by the geometric phase analysis of transmission electron microscopy. Phase manipulation by embedded sub micrometer dots allows us to deliver high-quality Ga2O3 with well-defined phases and to conceive advanced devices with ultra-low loss, high frequency, and memorizing functionality. [ABSTRACT FROM AUTHOR]

Solid state beam steering devices are key elements in low cost, robust, and three-dimensional imaging systems. Here, we present a silicon photonic beam steering device based upon an 8 × 8 grating coupler focal plane array approach fed by a thermo-optic Mach–Zehnder switching tree. In this device, transmission of light from the grating couplers is made through the backside of the chip using topside mirrors allowing for both high-efficiency out-coupling and direct flip-chip integration of drive electronics, providing a path to scale to denser focal plane arrays with large numbers of points in the future. A −13.8 dB fiber-to-fiber transmission was achieved in our preliminary test around 1523 nm for the beam steering chip. [ABSTRACT FROM AUTHOR]

In this work, we demonstrated the self-powered solar-blind photodetector based on a polyaniline/α-Ga2O3 hybrid heterojunction. The resultant device exhibited distinct self-power characteristics with a peak photoresponsivity (R) of 8.2 mA/W, a UVC (UV light of wavelength range at 200–280 nm)/UVA (UV light of wavelength range at 320–400 nm) rejection ratio (R220 nm/R400 nm) of 2.97 × 104, and a response decay time (τdec) of 176 μs at zero bias. With an elevated bias to 5 V, the dark current remained in an ultralow level of 0.21 pA, while the rejection ratio and τdec were improved to be 7.13 × 104 and 153 μs, respectively, together with the corresponding external quantum efficiency of 38.4% and a detectivity of 6.63 × 1013 Jones. Thanks to the dual functions of bandpass transmission in the deep-ultraviolet spectral region and the hole spreading transport of the polyaniline layer, the responsivity to the visible light is suppressed with the negligible internal photoemission effect, thus leading to the improved rejection ratio. Furthermore, weak interface interactions in such polyaniline/α-Ga2O3 organic–inorganic hybrid systems avoid the introduction of interfacial trapping centers by lattice mismatch and the stabilization of negatively charged anions (O2−) by (−NH2)-+species in polyaniline deactivate oxygen vacancies at the α-Ga2O3 surface, both of which lead to the negligible persistent photoconductivity effect. As a result, in the aid of the interfacial built-in field, the constructed hybrid heterojunction exhibited a self-powered detecting characteristic and a fast response speed. These findings verify the feasibility of delivering high performance photodetectors by implementing the inorganic/organic hybrid bipolar device design to overcome the difficulty in p-type Ga2O3. [ABSTRACT FROM AUTHOR]

Magnetotransport properties of La1-xCaxMnO3 (x=0.33, 0.5) thin films on different substrates are systematically studied. Due to the different lattice-substrate mismatch between films and substrates, compressive, and tensile epitaxial strain can be induced, respectively. The structure distortion induced by the strain with different sign influences the transport property and magnetoresistance. The tensile strain induces an increase of resistivity and magnetoresistance, while the resistivity peak temperature decreases. Compressive strain leads to a contrary behavior. The microstructure of films is also dominated by the lattice-substrate mismatch strongly. The inhomogeneities and different mixed domain structure induce the broadening of magnetic transition in films on SrTiO3 and NdGaO3, and a sharp increase in magnetoresistance in La0.67Ca0.33MnO3 films with increasing field. In addition, the low temperature metal–insulator transition in the resistivity of La0.5Ca0.5MnO3 film on LaAlO3 also indicates the sample inhomogeneities. The suppression of the charge-ordering state in La0.5Ca0.5MnO3 films is mainly dominated by the magnetic field, whereas the effect of the lattice-substrate mismatch is weak. It is due to the origin of the charge-ordering state. When the charge-ordering state is completely suppressed, the effect of lattice-substrate mismatch on charge transport and magnetoresistance shows up obviously. [ABSTRACT FROM AUTHOR]

The melting curves and structural properties of tantalum (Ta) are investigated by molecular dynamics simulations combining with potential model developed by Ravelo et al. [Phys. Rev. B 88, 134101 (2013)]. Before calculations, five potentials are systematically compared with their abilities of producing reasonable compressional and equilibrium mechanical properties of Ta. We have improved the modified-Z method introduced by Wang et al. [J. Appl. Phys. 114, 163514 (2013)] by increasing the sizes in Lx and Ly of the rectangular parallelepiped box (Lx=Ly « Lz). The influences of size and aspect ratio of the simulation box to melting curves are also fully tested. The structural differences between solid and liquid are detected by number density and local-order parameters Q6. Moreover, the atoms' diffusion with simulation time, defects, and vacancies formations in the sample are all studied by comparing situations in solid, solid-liquid coexistence, and liquid state. [ABSTRACT FROM AUTHOR]

The construction of Ga2O3-based p-n heterojunction offers an alternative strategy to realize bipolar power devices; however, lattice mismatch usually leads to undesirable device performance and makes interface engineering more challenging. In this work, we demonstrated the construction of lattice-matched p-n heterojunctions by the in situ hetero-epitaxy of p-type α-Ir2O3 on n-type Si-doped α-Ga2O3 using the mist-chemical vapor deposition technique. The α-Ga2O3/α-Ir2O3 p-n heterojunction shows single-crystalline corundum structures and well-defined rectifying characteristics. The transport mechanism has been identified to be space-charge-limited current conduction, which is induced by interfacial traps in an ultrathin disordered layer at the α-Ga2O3/α-Ir2O3 interface. Through thermal treatment in oxygen ambient, interfacial trapping states are suppressed, and more shallow acceptors of Ir vacancies are activated, both of which lead to the profound reduction of reverse leakage current, thus the improved current rectification ratio. The p-type α-Ir2O3 with advantages of lattice matching to α-Ga2O3 provides a promising strategy to realize high-performance bipolar power devices. [ABSTRACT FROM AUTHOR]

It was first suggested that terahertz imaging has the potential to detect skin cancer twenty years ago. Since then, THz instrumentation has improved significantly: real time broadband THz imaging is now possible and robust protocols for measuring living subjects have been developed. Here, we discuss the progress that has been made as well as highlight the remaining challenges for applying THz imaging to skin cancer detection. [ABSTRACT FROM AUTHOR]

In this Letter, high-performance β-Ga2O3 vertical heterojunction barrier Schottky (HJBS) diodes have been demonstrated together with the investigation of reverse leakage mechanisms. In HJBS configurations, NiO/β-Ga2O3 p-n heterojunctions and p-NiO field limiting rings (FLRs) are implemented by using a reactive sputtering technique at room temperature without intentional etching damages. Determined from the temperature-dependent current-voltage characteristics, the reverse leakage mechanism of the HJBS diode is identified to be Poole-Frenkel emission through localized trap sates with an energy level of EC-0.72 eV. With an uniform FLR width/spacing of 2 μm in HJBS, a maximum breakdown voltage (BV) of 1.89 kV and a specific on-resistance (Ron,sp) of 7.7 mΩ·cm2 are achieved, yielding a high Baliga's figure-of-merit (FOM, BV2/Ron,sp) of 0.46 GW/cm2. The electric field simulation and statistical experimental facts indicate that the electric field crowding effect at device edges is greatly suppressed by the shrinkage of p-NiO FLR spacing, and the capability of sustaining high BV is enhanced by the NiO/β-Ga2O3 bipolar structure, both of which contribute to the improved device performance. This work makes a significant step to achieve high performance β-Ga2O3 power devices by implementing alternative bipolar structures to overcome the difficulty in p-type β-Ga2O3. [ABSTRACT FROM AUTHOR]

A new pseudolocal tomography algorithm is developed for soft X-ray(SXR) imaging measurements of the turbulent electron temperature fluctuations (δ Te) in tokamaks and stellarators. The algorithm overcomes the constraints of limited viewing ports on the vessel wall (viewing angle) and limited number of lines of sight (LOS). This is accomplished by increasing the number of LOS locally in a region of interest. Numerical modeling demonstrates that the wavenumber spectrum of the turbulence can be reliably reconstructed, with an acceptable number of viewing angles and LOS and suitable low SNR detectors. We conclude that a SXR imaging diagnostic for measurements of turbulent δ Te using a pseudolocal reconstruction algorithm is feasible. [ABSTRACT FROM AUTHOR]

Mn-Fe-P-Ge alloys are promising, low cost, high performance candidates for magnetic cooling applications based on the magnetocaloric effect. These alloys undergo a magnetic phase transition which induces a large entropy change (DS). Experimental and modeling studies were conducted to study this transition for varying Ge content. Landau theory and the Bean-Rodbell model were applied to Mn1.1Fe0.9P1-xGex (x=0.26, 0.3, and 0.32) melt spun ribbons to model the phase transition and the associated entropy change. The critical behavior of these alloys was studied. The critical composition range at which the cross over from first order to second order magnetic transition occurs was determined. The calculated thermodynamic values and critical temperatures were in good agreement with our experimental results. A high maximum entropy change (ΔS) of ~44.9 J kg-1 K-1 was observed in Mn1.1Fe0.9P0.74Ge0.26 in a 5 T applied magnetic field. The results suggest that Mn-Fe-P-Ge alloys are very attractive materials for near room temperature magnetic cooling. [ABSTRACT FROM AUTHOR]

Effect of the metal/oxide interface on spin-dependent transport properties in perpendicular [Co/Pt]3 multilayers was investigated. The saturation Hall resistivity (ρxy) is significantly increased by 45% with 1.4 nm thick CoO layer inserted at the top Co/MgO interface; whereas it is increased only 25% with 1 nm thick CoO layer at the bottom MgO/Co interface. The interfacial structures characterized by X-ray photoelectron spectroscopy show that the MgO/Co interface and Co/MgO interface including chemical states play a dominant role on spin-dependent transport, leading to different anomalous Hall behavior. [ABSTRACT FROM AUTHOR]

The magnetic and transport properties of La0.7Sr0.3Mn1-xCoxO3 (0 ≤ x ≤ 1) samples were systematically studied. A magnetic phase diagram was constructed according to the observed results. At the two ends (x ≤ 0.3 and x > 0.9), the samples exhibit the conventional ferromagnetism with the metallic conducting behavior, which can be interpreted in terms of the double exchange coupling between Mn (Co) ions. As for the intermediate Co-doping region (0.3 < x < 0.9), the samples enter a mixed magnetic phase state, which displays the characteristics of the glassy states. According to the frequency-dependent results from the ac susceptibility, a representative frequency sensitivity factor K was calculated to be ~0.1 for the typical La0.7Sr0.3Mn0.6Co0.4O3 sample, corresponding to the coexistence of superparamagnetic-like free spins and the reentrant spin glass. The results of the Curie-Weiss fitting of the dc magnetization suggest that the Co3+ ions are in the intermediate spin state with the increase of Co-doping level (x ≥ 0.3), while the Co4+ ions show the spin state transition from the high spin state to the intermediate spin state at x = 0.6. The temperature dependence of resistivity shows a metal-insulator transition character for the intermediate Codoping samples, which can be well fitted by the three dimensional variable-range-hopping model in the whole temperature range. These facts suggest that the double exchange interaction in the perov- skite La0.7Sr0.3MnO3 is destroyed by the B site doping, due to the strong competition between the double exchange and superexchange interactions in Co/Mn ions as well as the frustration of spins in the system. [ABSTRACT FROM AUTHOR]

The magnetic and transport properties of La0.7Sr0.3Mn1-xCoxO3 (0 ≤ x ≤ 1) samples were systematically studied. A magnetic phase diagram was constructed according to the observed results. At the two ends (x ≤ 0.3 and x > 0.9), the samples exhibit the conventional ferromagnetism with the metallic conducting behavior, which can be interpreted in terms of the double exchange coupling between Mn (Co) ions. As for the intermediate Co-doping region (0.3 < x < 0.9), the samples enter a mixed magnetic phase state, which displays the characteristics of the glassy states. According to the frequency-dependent results from the ac susceptibility, a representative frequency sensitivity factor K was calculated to be ~0.1 for the typical La0.7Sr0.3Mn0.6Co0.4O3 sample, corresponding to the coexistence of superparamagnetic-like free spins and the reentrant spin glass. The results of the Curie-Weiss fitting of the dc magnetization suggest that the Co3+ ions are in the intermediate spin state with the increase of Co-doping level (x ≥ 0.3), while the Co4+ ions show the spin state transition from the high spin state to the intermediate spin state at x = 0.6. The temperature dependence of resistivity shows a metal-insulator transition character for the intermediate Codoping samples, which can be well fitted by the three dimensional variable-range-hopping model in the whole temperature range. These facts suggest that the double exchange interaction in the perov- skite La0.7Sr0.3MnO3 is destroyed by the B site doping, due to the strong competition between the double exchange and superexchange interactions in Co/Mn ions as well as the frustration of spins in the system. [ABSTRACT FROM AUTHOR]

There is a large number of missions that have been or will be launched soon that utilize the electric propulsion (EP), which is considered a key technology for applications in present and future space missions. Accomplishing an accurate measure of the thrust is a key aspect of the laboratory verification of EP systems. In the case of ground conditions and direct measurements, it is complicated to verify the thrusters, especially for some high power (>5 kW) thrusters. For this reason, we have developed an indirect method for measuring thrust. We have carried out an experiment with a Hall effect thruster (operated in the 250 W power range) and compared results against direct thrust measurements. The difficulties in the indirect measurement are analyzed, which provides a basis for the development of indirect thrust measurement. [ABSTRACT FROM AUTHOR]

The polycrystalline BaTiO3 (BTO) thin films were grown on F-doped SnO2 substrates by pulsed laser deposition. The devices show a rectification at a small voltage, while bipolar resistive switching (RS) and negative differential resistance (NDR) appear at a large voltage. Furthermore, RS remains and NDR disappears when no positive bias is applied, while both RS and NDR behaviors improve when increasing the positive bias. The electrons trapped/detrapped by interface states at Au/BTO interface are proposed to understand the above behaviors. [ABSTRACT FROM AUTHOR]

A series of ZnxFe3-xO4 (ZFO, x=0.4) thin films were epitaxially deposited on single-crystal (001)-SrTiO3 (STO) substrates by radio frequency magnetron sputtering. The anomalous thickness-dependent strain states of ZFO films were found, i.e., a tensile in-plane strain exists in the thinner ZFO film and which monotonously turns into compressive in the thicker films. Considering the lattice constant of bulk ZFO is bigger than that of STO, this strain state cannot be explained in the conventional framework of lattice-mismatch-induced strain in the hetero-epitaxial system. This unusual phenomenon is proposed to be closely related to the Volmer-Weber film growth mode in the thinner films and incorporation of the interstitial atoms into the island's boundaries during subsequent epitaxial growth of the thicker films. The ZFO/STO epitaxial film is found in the nature of magnetic semiconductor by transport measurements. The in-plane magnetization of the ZFO/STO films is found to increase as the in-plane compressive strain develops, which is further proved in the (001)-ZFO/PMN-PT film where the film strain state can be in situ controlled with applied electric field. This compressive-strain-enhanced magnetization can be attributed to the strain-mediated electric-field-induced in-plane magnetic anisotropy field enhancement. The above results indicate that strain engineering on magnetic oxide semiconductor ZFO films is promising for novel oxide-electronic devices. [ABSTRACT FROM AUTHOR]

The infrared dielectric property of monoclinic BaTeMo2O9 single crystals is studied by polarized IR reflectance spectra from 20 to 1800 cm-1. Based on the modified Lorentz model, the frequencies, strengths, and dampings of TO modes as well as the orientations of the dipole momenta are determined, agreeing well with Raman spectra and results from First-principles calculation. The observed modes are visually assigned to the specific atoms' motions in the primitive cell based on the theory calculations. A large shift of the internal modes of the anion groups relative to free anion co-ordination polyhedra is observed, which can be used to indicate the distortions of co-ordination polyhedra related to the nonlinear optical properties. Further, the experimental results of the strengths of the oscillators support the elimination and splitting of degenerate modes in free regular polyhedrons. These results offer a way to evaluate the nonlinear optical properties by use of traditional IR reflectivity spectra. [ABSTRACT FROM AUTHOR]

We have performed the study on the dependence of laser beam induced current (LBIC) spectra on the temperature for the vacancy-doped molecular beam epitaxy grown Hg1-xCdxTe (x = 0.31) photodiodes by both experiment and numerical simulations. It is found that the measured LBIC signal has different distributions for different temperature extents. The LBIC profile tends to be more asymmetric with increasing temperature below 170 K. But the LBIC profile becomes more symmetric with increasing temperature above 170 K. Based on a localized leakage model, it is indicated that the localized junction leakage can lead to asymmetric LBIC signal, in good agreement with the experimental data. The reason is that the trap-assisted tunneling current is the dominant leakage current at the cryogenic temperature below 170 K while the diffusion current component becomes dominant above the temperature of 170 K. The results are helpful for us to better clarify the mechanism of the dependence of LBIC spectra on temperature for the applications of HgCdTe infrared photodiodes. [ABSTRACT FROM AUTHOR]

In this Letter, we report on the evolution of electronic properties governed by epitaxial misfit strain in cubic In2O3 epilayers grown on sapphire. At elevated growth temperature, the competition between the film/substrate lattice mismatch and the thermal expansion mismatch alters the macroscopic biaxial strain from compressive to tensile. Simultaneously, the electron concentration is tuned from degeneration to non-degeneration density below the Mott criterion. The observed surface electron accumulation and metal-insulator transition result from the oxygen deficiency formed at low growth temperature, while high-temperature epitaxy is favorable to achieve remarkably enhanced mobility. The effective strain-property coupling suggests that the improved oxygen stoichiometry and the Fermi level movement controlled by the biaxial strains are responsible for the Mott transition. The strain-mediated reduction of the electron effective mass contributes to the enhanced intrinsic mobility in tensile-strained In2O3 epilayers. These results highlight that strain engineering is an effective stimulus to manipulate the transport properties of oxide semiconductors with improved performance and unexpected functionalities. [ABSTRACT FROM AUTHOR]

By analyzing a set of organic π radicals, we demonstrate that zero-point vibrational corrections give significant contributions to carbon hyperfine coupling constants, in one case even inducing a sign reversal for the coupling constant. We discuss the implications of these findings for the computational analysis of electron paramagnetic spectra based on hyperfine coupling constants evaluated at the equilibrium geometry of radicals. In particular, we note that a dynamical description that involves the nuclear motion is in many cases necessary in order to achieve a semi-quantitatively predictive theory for carbon hyperfine coupling constants. In addition, we discuss the implications of the strong dependence of the carbon hyperfine coupling constants on the zero-point vibrational corrections for the selection of exchange-correlation functionals in density functional theory studies of these constants. [ABSTRACT FROM AUTHOR]

A novel hybrid electrode structure using Ag nanowires (NWs) to create surface plasmons to enhance light trapping is designed and applied on the front surface of hydrogenated amorphous silicon (a-Si:H) solar cells on steel substrates, targeting broad-band absorption enhancements. Ag NWs were synthesized using a soft and self-seeding process. The produced Ag NWs were deposited on indium tin oxide (ITO) glass substrates or the ITO layers of the as-prepared flexible a-Si:H solar cells to form Ag NW-ITO hybrid electrodes. The Ag NW-ITO hybrid electrodes were optimized to achieve maximum optical enhancement using surface plasmons and obtain good electrical contacts in cells. Finite-element electromagnetic simulations confirmed that the presence of the Ag NWs resulted in increased electromagnetic fields within the a-Si:H layer. Compared to the cell with conventional ITO electrode, the measured quantum efficiency of the best performing a-Si:H cell shows an obvious enhancement in the wavelength range from 330 nm to 600 nm. The cell based on the optimized Ag NW-ITO demonstrates an increase about 4% in short-circuit current density and over 6% in power conversion efficiency under AM 1.5 illumination. [ABSTRACT FROM AUTHOR]