An extension of integrable equations related to AKNS and WKI spectral problems and their reductions
A novel hierarchy of integrable nonlinear evolution equations related to the combined Ablowitz-Kaup-Newell-Segur (AKNS) and Wadati-Konno-Ichikawa (WKI) spectral problems is proposed, from which the Lax pair for a corresponding negative flow and its infinite many conservation laws are obtained. Furthermore, a reduction of this hierarchy is discussed, by which a generalized sinh-Gordon equation is derived on the basis of its negative flow.
Integrability classification and exact solutions to generalized variable-coefficient nonlinear evolution equation
Constructing (2+1)-dimensional N=1 supersymmetric integrable systems from the Hirota formalism in the superspace
Shannon information entropies for rectangular multiple quantum well systems with constant total lengths
We first study the Shannon information entropies of constant total length multiple quantum well systems and then explore the effects of the number of wells and confining potential depth on position and momentum information entropy density as well as the corresponding Shannon entropy. We find that for small full width at half maximum (FWHM) of the position entropy density, the FWHM of the momentum entropy density is large and vice versa. By increasing the confined potential depth, the FWHM of the position entropy density decreases while the FWHM of the momentum entropy density increases. By increasing the potential depth, the frequency of the position entropy density oscillation within the quantum barrier decreases while that of the position entropy density oscillation within the quantum well increases. By increasing the number of wells, the frequency of the position entropy density oscillation decreases inside the barriers while it increases inside the quantum well. As an example, we might localize the ground state as well as the position entropy densities of the 1st, 2nd, and 6th excited states for a four-well quantum system. Also, we verify the Bialynicki-Birula-Mycieslki (BBM) inequality.
Comparative investigation of freezing phenomena for quantum coherence and correlations
Dynamics of entanglement protection of two qubits using a driven laser field and detunings: Independent and common, Markovian and/or non-Markovian regimes
Controlling the entanglement of mechanical oscillators in composite optomechanical system
Geometrical optics-based ray field tracing method for complex source beam applications
Due to the fact that traditional ray field tracking approaches require a large number of geometrical optical (GO) ray tubes, they are very inefficient in many practical applications. An improved ray model scheme for a complex source beam (CSB) tracking technique is proposed in this paper. The source field can be expressed by a superposition of CSBs, then every CSB basis function has a Gaussian-type amplitude distribution and is suitable for replacing a GO ray tube in the ray tracing approach. The complex phase matching technique is adopted to find the reflected beam in the reflection point where local approximation is used to represent the curved surface in its neighborhood. A new solution to multiple reflections using the conventional right-handed reflected system is used to track the field easily. Numerical results show the accuracy of the proposed method.
Nucleus-acoustic solitary waves in self-gravitating degenerate quantum plasmas
Stochastic resonance and synchronization behaviors of excitatory-inhibitory small-world network subjected to electromagnetic induction
A new nonlinear oscillator with infinite number of coexisting hidden and self-excited attractors
In this paper, we introduce a new two-dimensional nonlinear oscillator with an infinite number of coexisting limit cycles. These limit cycles form a layer-by-layer structure which is very unusual. Forty percent of these limit cycles are self-excited attractors while sixty percent of them are hidden attractors. Changing this new system to its forced version, we introduce a new chaotic system with an infinite number of coexisting strange attractors. We implement this system through field programmable gate arrays.
A new four-dimensional chaotic system with first Lyapunov exponent of about 22, hyperbolic curve and circular paraboloid types of equilibria and its switching synchronization by an adaptive global integral sliding mode control
This paper presents a new four-dimensional (4D) autonomous chaotic system which has first Lyapunov exponent of about 22 and is comparatively larger than many existing three-dimensional (3D) and 4D chaotic systems. The proposed system exhibits hyperbolic curve and circular paraboloid types of equilibria. The system has all zero eigenvalues for a particular case of an equilibrium point. The system has various dynamical behaviors like hyperchaotic, chaotic, periodic, and quasi-periodic. The system also exhibits coexistence of attractors. Dynamical behavior of the new system is validated using circuit implementation. Further an interesting switching synchronization phenomenon is proposed for the new chaotic system. An adaptive global integral sliding mode control is designed for the switching synchronization of the proposed system. In the switching synchronization, the synchronization is shown for the switching chaotic, stable, periodic, and hybrid synchronization behaviors. Performance of the controller designed in the paper is compared with an existing controller.
Time-varying formation for general linear multi-agent systems via distributed event-triggered control under switching topologies
Symmetry and asymmetry rogue waves in two-component coupled nonlinear Schrödinger equations
Quantum parameter estimation in a spin-boson dephasing quantum system by periodical projective measurements
Highly-sensitive NO, NO2, and NH3 measurements with an open-multipass cell based on mid-infrared wavelength modulation spectroscopy
Selection rules for electric multipole transition of triatomic molecule in scattering experiments
High-level theoretical study of the evolution of abundances and interconversion of glycine conformers
Density functional theory study of structural stability for gas hydrate
Using the first-principles method based on the density functional theory (DFT), the structures and electronic properties of different gas hydrates (CO2, CO, CH4, and H2) are investigated within the generalized gradient approximation. The structural stability of methane hydrate is studied in this paper. The results show that the carbon dioxide hydrate is more stable than the other three gas hydrates and its binding energy is -2.36 eV, and that the hydrogen hydrate is less stable and the binding energy is -0.36 eV. Water cages experience repulsion from inner gas molecules, which makes the hydrate structure more stable. Comparing the electronic properties of two kinds of water cages, the energy region of the hydrate with methane is low and the peak is close to the left, indicating that the existence of methane increases the stability of the hydrate structure. Comparing the methane molecule in water cages and a single methane molecule, the energy of electron distribution area of the former is low, showing that the filling of methane enhances the stability of hydrate structure.
Novel potential energy surface-based quantum dynamics of ion-molecule reaction O++D2 →OD++D
According to a novel electronic ground-state potential energy surface of H2O+(X4A"), we calculate the reaction probabilities and the integral cross section for the titled reaction O++D2 →OD++D by the Chebyshev wave packet propagation method. The reaction probabilities in a collision-energy range of 0.0 eV-1.0 eV show an oscillatory structure for the O++D2 reaction due to the existence of the potential well. Compared with the results of Martínez et al., the present integral cross section is large, which is in line with experimental data.
Dynamic stabilization of Na atom in an intense pulsed laser field
Corrections to atomic ground state energy due to interaction between atomic electric quadrupole and optical field
Quantitative evaluation of space charge effects of laser-cooled three-dimensional ion system on a secular motion period scale
In this paper, we introduce a method of quantitatively evaluating and controlling the space charge effect of a laser-cooled three-dimensional (3D) ion system in a linear Paul trap. The relationship among cooling efficiency, ion quantity, and trapping strength is analyzed quantitatively, and the dynamic space distribution and temporal evolution of the 3D ion system on a secular motion period time scale in the cooling process are obtained. The ion number influences the eigen-micromotion feature of the ion system. When trapping parameter q is~0.3, relatively ideal cooling efficiency and equilibrium temperature can be obtained. The decrease of axial electrostatic potential is helpful in reducing the micromotion heating effect and the degradation in the total energy. Within a single secular motion period under different cooling conditions, ions transform from the cloud state (each ion disperses throughout the envelope of the ion system) to the liquid state (each ion is concentrated at a specific location in the ion system) and then to the crystal state (each ion is subjected to a fixed motion track). These results are conducive to long-term storage and precise control, motion effect suppression, high-efficiency cooling, and increasing the precision of spectroscopy for a 3D ion system.
Design of scale model of plate-shaped absorber in a wide frequency range
All-fiber linearly polarized laser oscillator by fiber coiling loss control
Observation of self-Q-switching in bulk Yb: GdYSiO laser
Fundamental and dressed annular solitons in saturable nonlinearity with parity-time symmetric Bessel potential
Photonic crystal structures: Beam deflector and beam router
Head-on collision between two solitary waves in a one-dimensional bead chain
Oxidation during the production of FGH4095 superalloy powders by electrode induction-melt inert gas atomization
Super-clean and super-spherical FGH4095 superalloy powder is produced by the ceramic-free electrode induction-melt inert gas atomization (EIGA) technique. A continuous and steady-state liquid metal flow is achieved at high-frequency (350 kHz) alternating current and high electric power (100 kW). The superalloy is immersed in a high-frequency induction coil, and the liquid metal falling into a supersonic nozzle is atomized by an Ar gas of high kinetic gas energy. Numerical calculations are performed to optimize the structure parameters for the nozzle tip. The undesired oxidation reaction of alloying elements starts at 1000℃ with the reaction originating from the active sites on the powder surfaces, leading to the formation of oxides, MexOy. The role of active sites and kinetic factors associated with the diffusion of oxygen present in the atomization gas streams are also examined. The observed results reveal that the oxidation process occurring at the surface of the produced powders gradually moves toward the core, and that there exists a clear interface between the product layer and the reactant. The present study lays a theoretical foundation for controlling the oxidation of nickel-based superalloy powders from the powder process step.
Particle-in-cell simulation for the effect of magnetic cusp on discharge characteristics in a cylindrical Hall thruster
Phase shift effects of radio-frequency bias on ion energy distribution in continuous wave and pulse modulated inductively coupled plasmas
A retarding field energy analyzer (RFEA) is used to measure the time-averaged ion energy distributions (IEDs) on the substrate in both continuous wave (CW) and synchronous pulse modulated radio-frequency (RF) inductively coupled Ar plasmas (ICPs). The effects of the phase shift θ between the RF bias voltage and the RF source on the IED is investigated under various discharge conditions. It is found that as θ increases from 0 to π, the IED moves towards the low-energy side, and its energy width becomes narrower. In order to figure out the physical mechanism, the voltage waveforms on the substrate are also measured. The results show that as θ increases from 0 to π, the amplitude of the voltage waveform decreases and, meanwhile, the average sheath potential decreases as well. Specifically, the potential drop in the sheath on the substrate exhibits a maximum value at the same phase (i.e., θ=0) and a minimum value at the opposite phase (i.e., θ=π). Therefore, when ions traverse across the sheath region above the substrate, they obtain less energies at lower sheath potential drop, leading to lower ion energy. Besides, as θ increases from π to 2π, the IEDs and their energy widths change reversely.
Wettability of Si and Al-12Si alloy on Pd-implanted 6H-SiC
The influence of surface effects on Frederiks transition in nematic liquid crystal doped with ferroelectric nanoparticles
Two-dimensional electron gas characteristics of InP-based high electron mobility transistor terahertz detector
The effect of replacing pnictogen elements on the physical properties of SrMg2X2 (X=N, P, As, Sb, Bi) Zintl compounds
Passivation of carbon dimer defects in amorphous SiO2/4H-SiC (0001) interface: A first-principles study
Influence of spin-orbit coupling on spin-polarized electronic transport in magnetic semiconductor nanowires with nanosized sharp domain walls
Effect of depositing PCBM on perovskite-based metal-oxide-semiconductor field effect transistors
Room-temperature operating extended short wavelength infrared photodetector based on interband transition of InAsSb/GaSb quantum well
Here in this paper, we report a room-temperature operating infrared photodetector based on the interband transition of an InAsSb/GaSb quantum well. The interband transition energy of 5-nm thick InAs0.91Sb0.09 embedded in the GaSb barrier is calculated to be 0.53 eV (2.35 μm), which makes the absorption range of InAsSb cover an entire range from short-wavelength infrared to long-wavelength infrared spectrum. The fabricated photodetector exhibits a narrow response range from 2.0 μm to 2.3 μm with a peak around 2.1 μm at 300 K. The peak responsivity is 0.4 A/W under -500 -mV applied bias voltage, corresponding to a peak quantum efficiency of 23.8% in the case without any anti-reflection coating. At 300 K, the photodetector exhibits a dark current density of 6.05×10-3 A/cm2 under -400-mV applied bias voltage and 3.25×10-5 A/cm2 under zero, separately. The peak detectivity is 6.91×1010 cm·Hz1/2/W under zero bias voltage at 300 K.
Conductivity and band alignment of LaCrO3/SrTiO3 (111) heterostructure
In this work, we investigate the electrical transport property and electronic structure of oxide heterostructure LaCrO3/SrTiO3 (111). The interface grown under relatively low oxygen partial pressure is found to be metallic with a conducting critical thickness of 11 unit cells of LaCrO3. This criticality is also observed by x-ray photoelectron spectroscopy, in which the Ti3+ signal intensity at the spectrum edge of the Ti-2p3/2 core level increases rapidly when the critical thickness is reached. The variations of the valence band offset and full width at half maximum of the core-level spectrum with LaCrO3 thickness suggest that the built-in fields exist both in LaCrO3 and in SrTiO3. Two possible origins are proposed:the charge transfer from LaCrO3 and the formation of a quantum well in SrTiO3. Our results shed light on the understanding of the doping mechanism at the polar/non-polar oxide interface. Moreover, due to the interesting lattice and spin structure of LCO in the (111) direction, our work provides a basis for further exploring the novel topological quantum phenomena in this system.
Gap plasmon-enhanced photoluminescence of monolayer MoS2 in hybrid nanostructure Hot!
Monolayer transition-metal dichalcogenides (TMDs) have attracted a lot of attention for their applications in optics and optoelectronics. Molybdenum disulfide (MoS2), as one of those important materials, has been widely investigated due to its direct band gap and photoluminescence (PL) in visible range. Owing to the fact that the monolayer MoS2 suffers low light absorption and emission, surface plasmon polaritons (SPPs) are used to enhance both the excitation and emission efficiencies. Here, we demonstrate that the PL of MoS2 sandwiched between 200-nm-diameter gold nanoparticle (AuNP) and 150-nm-thick gold film is improved by more than 4 times compared with bare MoS2 sample. This study shows that gap plasmons can possess more optical and optoelectronic applications incorporating with many other emerging two-dimensional materials.
Double band-inversions of bilayer phosphorene under strain and their effects on optical absorption
Strain is a powerful tool to engineer the band structure of bilayer phosphorene. The band gap can be decreased by vertical tensile strain or in-plane compressive strain. At a critical strain, the gap is closed and the bilayer phosphorene is turn to be a semi-Dirac semimetal material. If the strain is stronger than the criterion, a band-inversion occurs and it re-happens when the strain is larger than another certain value. For the zigzag bilayer phosphorene ribbon, there are two edge band dispersions and each dispersion curve represents two degenerate edge bands. When the first band-inversion happens, one of the edge band dispersion disappears between the band-cross points while the other survives, and the latter will be eliminated between another pair of band-cross points of the second band-inversion. The optical absorption of bilayer phosphorene is highly polarized along armchair direction. When the strain is turn on, the optical absorption edge changes. The absorption rate for armchair polarized light is decreased by gap shrinking, while that for zigzag polarized light increases. The band-touch and band-inversion respectively result in the sublinear and linear of absorption curve versus light frequency in low frequency limit.
Bias polarity-dependent unipolar switching behavior in NiO/SrTiO3 stacked layer
Low specific on-resistance GaN-based vertical heterostructure field effect transistors with nonuniform doping superjunctions
Influence of fin architectures on linearity characteristics of AlGaN/GaNFinFETs
Topological phase diagrams and Majorana zero modes of the Kitaev ladder and tube
In this paper, we study two quasi-one-dimensional (1D) Kitaev models with ladder-like and tube-like spatial structures, respectively. Our results provide the phase diagrams and explicit expressions of the Majorana zero modes. The topological phase diagrams are obtained by decomposing the topological invariants and the topological conditions for topologically nontrivial phases are given precisely. For systems which belongs to topological class BDI, we obtain the regions in the phase diagrams where the topological numbers show even-odd effect. For the Kitaev tube model a phase factor induced by the magnetic flux in the axial direction of the tube is introduced to alter the classification of the tube Hamiltonian from class BDI to D. The Kitaev tube of class D is characterized by the Z2 index when the number of chains is odd while 0, 1, 2 when the number of chains is even. The phase diagrams show periodic behaviors with respect to the magnetic flux. The bulk-boundary correspondence is demonstrated by the observations that the topological conditions for the bulk topological invariant to take nontrivial values are precisely those for the existence of the Majorana zero modes.
The structure and elasticity of phase B silicates under high pressure by first principles simulation
Distinction between critical current effects and intrinsic anomalies in the point-contact Andreev reflection spectra of unconventional superconductors Hot!
In this work, we discuss the origin of several anomalies present in the point-contact Andreev reflection spectra of (Li1-xFex)OHFeSe, LiTi2O4, and La2-xCexCuO4. While these features are similar to those stemming from intrinsic superconducting properties, such as Andreev reflection, electron-boson coupling, multigap superconductivity, d-wave and p-wave pairing symmetry, they cannot be accounted for by the modified Blonder-Tinkham-Klapwijk (BTK) model, but require to consider critical current effects arising from the junction geometry. Our results point to the importance of tracking the evolution of the dips and peaks in the differential conductance as a function of the bias voltage, in order to correctly deduce the properties of the superconducting state.
Composition design for (PrNd-La–Ce)2Fe14B melt-spun magnets by machine learning technique
Data-driven technique is a powerful and efficient tool for guiding materials design, which could supply as an alternative to trial-and-error experiments. In order to accelerate composition design for low-cost rare-earth permanent magnets, an approach using composition to estimate coercivity (Hcj) and maximum magnetic energy product ((BH)max) via machine learning has been applied to (PrNd-La-Ce)2Fe14B melt-spun magnets. A set of machine learning algorithms are employed to build property prediction models, in which the algorithm of Gradient Boosted Regression Trees is the best for predicting both Hcj and (BH)max, with high accuracies of R2=0.88 and 0.89, respectively. Using the best models, predicted datasets of Hcj or (BH)max in high-dimensional composition space can be constructed. Exploring these virtual datasets could provide efficient guidance for materials design, and facilitate the composition optimization of 2:14:1 structure melt-spun magnets. Combined with magnets' cost performance, the candidate cost-effective magnets with targeted properties can also be accurately and rapidly identified. Such data analytics, which involves property prediction and composition design, is of great time-saving and economical significance for the development and application of LaCe-containing melt-spun magnets.
Investigation of magnetization reversal process in pinned CoFeB thin film by in-situ Lorentz TEM
Exchange bias effect has been widely employed for various magnetic devices. The experimentally reported magnitude of exchange bias field is often smaller than that predicted theoretically, which is considered to be due to the partly pinned spins of ferromagnetic layer by antiferromagnetic layer. However, mapping the distribution of pinned spins is challenging. In this work, we directly image the reverse domain nucleation and domain wall movement process in the exchange biased CoFeB/IrMn bilayers by Lorentz transmission electron microscopy. From the in-situ experiments, we obtain the distribution mapping of the pinning strength, showing that only 1/6 of the ferromagnetic layer at the interface is strongly pinned by the antiferromagnetic layer. Our results prove the existence of an inhomogeneous pinning effect in exchange bias systems.
First-order reversal curve investigated magnetization switching in Pd/Co/Pd wedge film
The magnetization switching plays an essential role in spintronic devices. In this study, a Pd(3 nm)/Co(0.14-1.68 nm)/Pd(5 nm) wedge film is deposited on an MgO (111) substrate by molecular beam epitaxy. We investigate the polar magneto-optical Kerr effect (MOKE) and carry out the first-order reversal curve (FORC) measurements. For the wedge system, it is observed that the Co thickness could drive the spin reorientation transition (SRT) from out-of-plane to in-plane. Meanwhile, we find the different types of magnetization switchings in the continuous SRT process, which can originate from the formation of different magnetic compositions. Our work provides the possibility of tuning the interfacial effect, and paves the way to analyzing magnetization switching.
Linear and nonlinear optical analysis on semiorganic L-proline cadmium chloride single crystal
In the current investigation, L-proline cadmium chloride monohydrate (LPCC) single crystal is grown by a slow solvent evaporation technique to identify its credibility for nonlinear optical device applications. The constituent elements of LPCC crystal are determined by the energy dispersive spectroscopic (EDS) technique. The single crystal x-ray diffraction technique is used to determine the structural dimensions of LPCC crystal. The UV-visible studies are carried out within a wavelength range of 200 nm-1100 nm to determine the optical transmittance of LPCC crystal. The linear optical parameters of LPCC crystal are evaluated using the transmittance data to discuss its importance for distinct optical devices. The Nd:YAG laser assisted Kurtz-Perry test is carried out to determine the enhancement in second harmonic generation efficiency of LPCC crystal with reference to KDP crystal. The Z-scan technique is employed to assess the third order nonlinear optical (TONLO) properties of LPCC crystal at 632.8 nm. The Z-scan data are utilized to evaluate the TONLO refraction, absorption and susceptibility of LPCC crystal. The color oriented luminescence behavior of LPCC crystal is investigated within a spectral range of 350 nm-700 nm. The dependence of dielectric constant and dielectric loss on temperature and frequency is evaluated through the dielectric measurement studies.
Structural, electronic, vibrational, and thermodynamic properties of Zr1-xHfxCo: A first-principles-based study
Characteristic improvements of thin film AlGaInP red light emitting diodes on a metallic substrate
We report a type of thin film AlGaInP red light emitting diode (RLED) on a metallic substrate by electroplating copper (Cu) to eliminate the absorption of GaAs grown substrate. The fabrication of the thin film RLED is presented in detail. Almost no degradations of epilayers properties are observed after this substrate transferred process. Photoluminescence and electroluminescence are measured to investigate the luminous characteristics. The thin film RLED shows a significant enhancement of light output power (LOP) by improving the injection efficiency and light extraction efficiency compared with the reference RLED on the GaAs parent substrate. The LOPs are specifically enhanced by 73.5% and 142% at typical injections of 2 A/cm2 and 35 A/cm2 respectively from electroluminescence. Moreover, reduced forward voltages, stable peak wavelengths and full widths at half maximum are obtained with the injected current increasing. These characteristic improvements are due to the Cu substrate with great current spreading and the back reflection by bottom electrodes. The substrate transferred technology based on electroplating provides an optional way to prepare high-performance optoelectronic devices, especially for thin film types.
Hot spots enriched plasmonic nanostructure-induced random lasing of quantum dots thin film
Here, a plasmon-enhanced random laser was achieved by incorporating gold nanostars (NS) into disordered polymer and CdSe/ZnS quantum dots (QDs) gain medium films, in which the surface plasmon resonance of gold NS can greatly enhance the scattering cross section and bring a large gain volume. The random distribution of gold NS in the gain medium film formed a laser-mode resonator. Under a single-pulse pumping, the scattering center of gold NS-based random laser exhibits enhanced performance of a lasing threshold of 0.8 mJ/cm2 and a full width as narrow as 6 nm at half maximum. By utilizing the local enhancement characteristic of the electric field at the sharp apexes of the gold NS, the emission intensity of the random laser was increased. In addition, the gold NS showed higher thermal stability than the silver nanoparticles, withstanding high temperature heating up to 200℃. The results of metal nanostructures with enriched hot spots and excellent temperature stability have tremendous potential applications in the fields of biological identification, medical diagnostics, lighting, and display devices.
Off-stoichiometry indexation of BiFeO3 thin film on silicon by Rutherford backscattering spectrometry
Effects of growth conditions on optical quality and surface morphology of InGaAsBi
Structural and electrical properties of reactive magnetron sputtered yttrium-doped HfO2 films
Hafnium oxide thin films doped with different concentrations of yttrium are prepared on Si (100) substrates at room temperature using a reactive magnetron sputtering system. The effects of Y content on the bonding structure, crystallographic structure, and electrical properties of Y-doped HfO2 films are investigated. The x-ray photoelectron spectrum (XPS) indicates that the core level peak positions of Hf 4f and O 1s shift toward lower energy due to the structure change after Y doping. The depth profiling of XPS shows that the surface of the film is completely oxidized while the oxygen deficiency emerges after the stripping depths have increased. The x-ray diffraction and high resolution transmission electron microscopy (HRTEM) analyses reveal the evolution from monoclinic HfO2 phase towards stabilized cubic HfO2 phase and the preferred orientation of (111) appears with increasing Y content, while pure HfO2 shows the monoclinic phase only. The leakage current and permittivity are determined as a function of the Y content. The best combination of low leakage current of 10-7 A/cm2 at 1 V and a highest permittivity value of 29 is achieved when the doping ratio of Y increases to 9 mol%. A correlation among Y content, phase evolution and electrical properties of Y-doped HfO2 ultra-thin film is investigated.
Low-temperature synthesis of apatite-type La9.33Ge6O26 as electrolytes with high conductivity
In the present study, high-quality apatite-type La9.33Ge6O26 powders are successfully synthesized by a facile molten-salt synthesis method (MSSM) at low temperatures, using LiCl, LiCl/NaCl mixture (mass ratio 1:1) as molten salt, respectively. Experimental results indicate that the optimal mass ratio between reactant and molten salt is 1:2, and LiCl/NaCl mixed molten-salt is more beneficial for forming high-quality La9.33Ge6O26 powders than LiCl individual molten-salt. Comparing with the conventional solid-state reaction method (SSRM), the synthesis temperature of apatite-type La9.33Ge6O26 powders using the MSSM decreases more than 350℃, which can effectively avoid Ge loss in the preparation process of precursor powders. Furthermore, the powders obtained by the MSSM are homogeneous, non-agglomerated and well crystallized, which are very favorable for gaining dense pellets in the premise of avoiding Ge loss. On the basis of high-quality precursor powders, the dense and pure ceramic pellets of La9.33Ge6O26 are gained at a low temperature of 1100℃ for 2 h, which exhibit higher conductivities (σ 850℃(LiCl)=2.3×10-2 S·cm-1, σ 850℃(LiCl/NaCl)=4.9×10-2 S·cm-1) and lower activation energies (Ea(LiCl)=1.02 eV, Ea(LiCl/NaCl)=0.99 eV) than that synthesized by the SSRM.
Scalability of dark current in silicon PIN photodiode
Closed-form breakdown voltage/specific on-resistance model using charge superposition technique for vertical power double-diffused metal-oxide-semiconductor device with high-κ insulator
An improved vertical power double-diffused metal-oxide-semiconductor (DMOS) device with a p-region(P1) and high-κ insulator vertical double-diffusion metal-oxide-semiconductor (HKP-VDMOS) is proposed to achieve a better performance on breakdown voltage (BV)/specific on-resistance (Ron,sp) than conventional VDMOS with a high-κ insulator (CHK-VDMOS). The main mechanism is that with the introduction of the P-region, an extra electric field peak is generated in the drift region of HKP-VDMOS to enhance the breakdown voltage. Due to the assisted depletion effect of this p-region, the specific on-resistance of the device could be reduced because of the high doping density of the N-type drift region. Meanwhile, based on the superposition of the depleted charges, a closed-form model for electric field/breakdown voltage is generally derived, which is in good agreement with the simulation result within 10% of error. An HKP-VDMOS device with a breakdown voltage of 600 V, a reduced specific on-resistance of 11.5 mΩ·cm2 and a figure of merit (FOM) (BV2/Ron,sp) of 31.2 MW·cm-2 shows a substantial improvement compared with the CHK-VDMOS device.
Research on the radiation hardened SOI devices with single-step Si ion implantation
Silicon-on-insulator (SOI) devices are sensitive to the total ionizing dose effect due to the existence of buried oxide. In this paper, an extra single-step Si ion implantation into buried oxide layer prior to the normal complementary metal-oxide-semiconductor transistor (CMOS) process is used to harden the SOI wafer. The top-Si quality of the hardened SOI wafer is confirmed to be good enough for device manufacturing through various characterization methods. The radiation experiments show that the total ionizing dose tolerance of the Si implanted SOI device is improved significantly. The metastable electron traps introduced by Si implantation is also investigated by electrical stress. The results show that these traps are very instable, and electrons will tunnel into or out of the metastable electron traps quickly after hot-electron-injection or hot-hole-injection.
Water-based processed and alkoxide-based processed indium oxide thin-film transistors at different annealing temperatures
Analytically determining frequency and amplitude of spontaneous alpha oscillation in Jansen's neural mass model using the describing function method
Spontaneous alpha oscillations are a ubiquitous phenomenon in the brain and play a key role in neural information processing and various cognitive functions. Jansen's neural mass model (NMM) was initially proposed to study the origin of alpha oscillations. Most of previous studies of the spontaneous alpha oscillations in the NMM were conducted using numerical methods. In this study, we aim to propose an analytical approach using the describing function method to elucidate the spontaneous alpha oscillation mechanism in the NMM. First, the sigmoid nonlinear function in the NMM is approximated by its describing function, allowing us to reformulate the NMM and derive its standard form composed of one nonlinear part and one linear part. Second, by conducting a theoretical analysis, we can assess whether or not the spontaneous alpha oscillation would occur in the NMM and, furthermore, accurately determine its amplitude and frequency. The results reveal analytically that the interaction between linearity and nonlinearity of the NMM plays a key role in generating the spontaneous alpha oscillations. Furthermore, strong nonlinearity and large linear strength are required to generate the spontaneous alpha oscillations.