The supply voltage scaled dependency of the recovery of single event upset in advanced complementary metal-oxide-semiconductor static random-access memory cells

Using computer-aided design three-dimensional simulation technology,the supply voltage scaled dependency of the recovery of single event upset and charge collection in static random-access memory cells are investigated.It reveals that the recovery linear energy transfer threshold decreases with the supply voltage reducing,which is quite attractive for dynamic voltage scaling and subthreshold circuit radiation-hardened design.Additionally,the effect of supply voltage on charge collection is also investigated.It is concluded that the supply voltage mainly affects the bipolar gain of the parasitical bipolar junction transistor(BJT) and the existence of the source plays an important role in supply voltage variation.     

Study on the pre-chopper in CSNS LEBT

Physical designing of the pre-chopper in CSNS LEBT is carried out, which includes the deflecting voltage, the length and the width of the deflecting plates, and the gap between the deflecting plates. The most outstanding feature of the design is that both the gap and the width vary with the beam envelope size. So both the requried deflecting voltage and the loaded capacitance are lowered. In order to avoid destruction of the space charge neutralization by the pre-chopper in the whole LEBT, an electron-trapping electrode is arranged to confine the electrostatic field of the pre-chopper to the local area. To examine the reliability of the pre-chopping design in CSNS LEBT, a similar pre-chopping design in ADS RFQ LEBT is set up and an experiment on the pre-chopper is prepared. 3-dimensional simulations are carried out to determine the loaded capacitance and the applied voltage of the electron-trapping electrode.     

A highly pixelated CdZnTe detector based on Topmetal-II~- sensor

Topmetal-Ⅱ~-is a low noise CMOS pixel direct charge sensor with a pitch of 83 μm.CdZnTe is an excellent semiconductor material for radiation detection.The combination of CdZnTe and the sensor makes it possible to build a detector with high spatial resolution.In our experiments,an epoxy adhesive is used as the conductive medium to connect the sensor and cadmium zinc telluride(CdZnTe).The diffusion coefficient and charge efficiency of electrons are measured at a low bias voltage of-2 V,and the image of a single alpha particle is clear with a reasonable spatial resolution.A detector with such a structure has the potential to be applied in X-ray imaging systems with further improvements of the sensor.     

MOS-based model of four-transistor CMOS image sensor pixels for photoelectric simulation

By using the MOS-based model established in this paper, the physical process of photoelectron generation, transfer, and storage in the four-transistor active pixel sensor (4T-APS) pixels can be simulated in SPICE environment. The variable capacitance characteristics of double junctions in pinned photodiodes (PPDs) and the threshold voltage difference formed by channel nonuniform doping in transfer gates (TGs) are considered with this model. The charge transfer process of photogenerated electrons from PPDs to the floating diffusion (FD) is analyzed, and the function of nonuniform doping of TGs in suppressing charge injection back to PPDs is represented with the model. The optical and electrical characteristics of all devices in the pixel are effectively combined with the model. Moreover, the charge transfer efficiency and the voltage variation in PPD can be described with the model. Compared with the hybrid simulation in TCAD and the Verilog-A simulation in SPICE, this model has higher simulation efficiency and accuracy, respectively. The effectiveness of the MOS-based model is experimentally verified in a 3 μ m test pixel designed in 0.11 μ m CIS process.     

Influence of sub-bandgap illumination on space charge distribution in CdZnTe detector

The space charge accumulation in CdZnTe crystals seriously affects the performance of high-flux pulse detectors.The influence of sub-bandgap illumination on the space charge distribution and device performance in CdZnTe crystals were studied theoretically by Silvaco TCAD software simulation.The sub-bandgap illumination with a wavelength of 890 nm and intensity of 8×10?8 W/cm2 were used in the simulation to explore the space charge distribution and internal electric field distribution in CdZnTe crystals.The simulation results show that the deep level occupation faction is manipulated by the sub-bandgap illumination,thus space charge concentration can be reduced under the bias voltage of 500 V.A flat electric field distribution is obtained,which significantly improves the charge collection efficiency of the CdZnTe detector.Meanwhile,premised on the high resistivity of CdZnTe crystal,the space charge concentration in the crystal can be further reduced with the wavelength of 850 nm and intensity of 1×10?7 W/cm2 illumination.The electric field distribution is flatter and the carrier collection efficiency of the device can be improved more effectively.     

Impact of proton-induced alteration of carrier lifetime on single-event transient in SiGe heterojunction bipolar transistor

This paper presents an investigation into the impact of proton-induced alteration of carrier lifetime on the singleevent transient(SET) caused by heavy ions in silicon–germanium heterojunction bipolar transistor(SiGe HBT).The ioninduced current transients and integrated charge collections under different proton fluences are obtained based on technology computer-aided design(TCAD) simulation.The results indicate that the impact of carrier lifetime alteration is determined by the dominating charge collection mechanism at the ion incident position and only the long-time diffusion process is affected.With a proton fluence of 5 × 10~(13) cm~(-2), almost no change is found in the transient feature, and the charge collection of events happened in the region enclosed by deep trench isolation(DTI), where prompt funneling collection is the dominating mechanism.Meanwhile, for the events happening outside DTI where diffusion dominates the collection process, the peak value and the duration of the ion-induced current transient both decrease with increasing proton fluence, leading to a great decrease in charge collection.     

Dynamic analysis of Bernoulli-Euler piezoelectric nanobeam with electrostatic force

The effect of electrostatic force on the dynamic response of a Bernoulli-Euler piezoelectric nanobeam is analyzed in this paper.The governing equations with the electrostatic stress are derived based on a variational principle.Static bending problem of simply supported and cantilever beam is considered.The influence of the electrostatic force on the first four natural frequencies is discussed.It is shown that when the beam thickness is small,the effect of the electrostatic force is significant.When the beam thickness is large,the electrostatic force is insignificant and can be neglected.The results also indicate that one can adjust the natural frequency of a nanobeam by applying appropriate voltage.     

Magnetic phase transition and magnetocaloric effect in Mn_(1-x)Zn_xCoGe alloys

The magnetic phase transition and magnetocaloric effect are studied in a series of Mn1-xZnxCoGe(x = 0.01, 0.02,0.04, and 0.08) alloys. By introducing a small quantity of Zn element, the structural transformation temperature of the MnCoGe alloy is greatly reduced and a first-order magnetostructural transition is observed. Further increasing the Zn concentration results in a second-order ferromagnetic transition. Large room-temperature magnetocaloric effects with small magnetic hysteresis are obtained in alloys with x = 0.01 and 0.02, which suggests their potential application in magnetic refrigeration.     

Electrostatic interaction of a spherical particle in the vicinity of a circular orifice

The electrostatic interaction of a charged spherical particle in the vicinity of an orifice plane has been investigated in this paper.The particle can creep along the axis of the orifice and is immersed in a bulk electrolyte.By solving the Poisson-Boltzmann problem,we have obtained the effective electrostatic interaction for several values of reduced orifice radius h,including the cases of h > 1,h = 1 and h < 1.Two kinds of boundary conditions of the orifice plane are considered.One is the constant potential model corresponding to a conducting plane,the other is the constant charge model.In the constant potential model,there is an electrostatic attraction between the particle and the orifice plane when they get close to each other,while there is a pure electrostatic repulsion in the constant charge model.The interactions in both boundary models are sensitive to the parameters of the reduced orifice radius,the reduced particle-orifice distance,surface charge densities of the particle and orifice plane,and the reduced Debye screen constant corresponding to the salt-ion concentration and ion valence.     

An efficient numerical approach to electrostatic microelectromechanical system simulation

Computational analysis of electrostatic microelectromechanical systems (MEMS) requires an electrostatic analysis to compute the electrostatic forces acting on micromechanical structures and a mechanical analysis to compute the deformation of micromechanical structures.Typically,the mechanical analysis is performed on an undeformed geometry.However,the electrostatic analysis is performed on the deformed position of microstructures.In this paper,a new efficient approach to self-consistent analysis of electrostatic MEMS in the small deformation case is presented.In this approach,when the microstructures undergo small deformations,the surface charge densities on the deformed geometry can be computed without updating the geometry of the microstructures.This algorithm is based on the linear mode shapes of a microstructure as basis functions.A boundary integral equation for the electrostatic problem is expanded into a Taylor series around the undeformed configuration,and a new coupled-field equation is presented.This approach is validated by comparing its results with the results available in the literature and ANSYS solutions,and shows attractive features comparable to ANSYS.     

Adiabatic cooling for cold polar molecules on a chip using a controllable high-efficiency electrostatic surface trap

We propose a controllable high-efficiency electrostatic surface trap for cold polar molecules on a chip by using two insulator-embedded charged rings and a grounded conductor plate. We calculate Stark energy structure pattern of ND3 molecules in an external electric field using the method of matrix diagonalization. We analyze how the voltages that are applied to the ring electrodes affect the depth of the efficient well and the controllability of the distance between the trap center and the surface of the chip. To obtain a better understanding, we simulate the dynamical loading and trapping processes of ND3 molecules in a ｜J, KM = ｜1,-1 state by using classical Monte–Carlo method. Our study shows that the loading efficiency of our trap can reach ～ 88%. Finally, we study the adiabatic cooling of cold molecules in our surface trap by linearly lowering the potential-well depth（i.e., lowering the trapping voltage）, and find that the temperature of the trapped ND3 molecules can be adiabatically cooled from 34.5 m K to ～ 5.8 m K when the trapping voltage is reduced from-35 k V to-3 k V.     

Calculation and analysis of the number of return photons from sodium laser beacon excited by the long pulse laser with circular polarization

The number of return photons from sodium laser beacon（SLB） greatly suffers down-pumping, recoil, and geomagnetic field when the long pulse laser with circular polarization interacts with sodium atoms in the mesosphere. Considering recoil and down-pumping effects on the number of return photons from SLB, the spontaneous radiation rates are obtained by numerical computations and fittings. Furthermore, combining with the geomagnetic field effects, a new expression is achieved for calculating the number of return photons. By using this expression and considering the stochastic distribution of laser intensity in the mesosphere under different turbulence models for atmosphere, the number of return photons excited by the narrow-band single mode laser and that by the narrow-band three-mode laser are respectively calculated. The results show that the narrow-band three-mode laser with a specific spectrum structure has a higher spontaneous radiation rate and more return photons than a narrow-band single mode laser. Of note, the effect of the atmospheric turbulence on the number of return photons is remarkable. Calculation results indicate that the number of return photons under the HV5/7 model for atmospheric turbulence is much higher than that under the Greenwood and Mod HV models.     

Exact Solutions and Invariant Sets to General Reaction-Diffusion Equation

In this paper, we introduce new invariant sets, and the invariant sets and exact solutions to general reactiondiffusion equation are discussed. It is shown that there exist a class of exact solutions to the equations that belong to the invariant sets.     

Effects of N doping on photoelectric properties of along different directions of ZnO bulk and nanotube

The electronic structures and optical properties of N-doped Zn O bulks and nanotubes are investigated using the firstprinciples density functional method. The calculated results show that the main optical parameters of Zn O bulks are isotropic（especially in the high frequency region）, while Zn O nanotubes exhibit anisotropic optical properties. N doping results show that Zn O bulks and nanotubes present more obvious anisotropies in the low-frequency region. Thereinto, the optical parameters of N-doped Zn O bulks along the [100] direction are greater than those along the [001] direction, while for N-doped nanotubes, the variable quantities of optical parameters along the [100] direction are less than those along the[001] direction. In addition, refractive indexes, electrical conductivities, dielectric constants, and absorption coefficients of Zn O bulks and nanotubes each contain an obvious spectral band in the deep ultraviolet（UV）（100 nm～ 300 nm）. For each of N-doped Zn O bulks and nanotubes, a spectral peak appears in the UV and visible light region, showing that N doping can broaden the application scope of the optical properties of Zn O.     

Relativistic effect of pseudospin symmetry and tensor coupling on the Mie-type potential via Laplace transformation method

A relativistic Mie-type potential for spin-1/2 particles is studied. The Dirac Hamiltonian contains a scalar S（r） and a vector V（r） Mie-type potential in the radial coordinates, as well as a tensor potential U（r） in the form of Coulomb potential. In the pseudospin（p-spin） symmetry setting Σ = Cps and Δ = V（r）, an analytical solution for exact bound states of the corresponding Dirac equation is found. The eigenenergies and normalized wave functions are presented and particular cases are discussed with any arbitrary spin–orbit coupling number κ. Special attention is devoted to the caseΣ = 0 for which p-spin symmetry is exact. The Laplace transform approach（LTA） is used in our calculations. Some numerical results are obtained and compared with those of other methods.     

A spherical higher-order finite-difference time-domain algorithm with perfectly matched layer

A higher-order finite-difference time-domain（HO-FDTD） in the spherical coordinate is presented in this paper. The stability and dispersion properties of the proposed scheme are investigated and an air-filled spherical resonator is modeled in order to demonstrate the advantage of this scheme over the finite-difference time-domain（FDTD） and the multiresolution time-domain（MRTD） schemes with respect to memory requirements and CPU time. Moreover, the Berenger＇s perfectly matched layer（PML） is derived for the spherical HO-FDTD grids, and the numerical results validate the efficiency of the PML.     

Embedded-Soliton and Complex Wave Excitations of （3＋1）-Dimensional Burgers System

Starting from the extended mapping approach and a linear variable separation method, we find new families of variable separation solutions with some arbitrary functions for the （3＋1）-dimensionM Burgers system. Then based on the derived exact solutions, some novel and interesting localized coherent excitations such as embedded-solitons, taper-like soliton, complex wave excitations in the periodic wave background are revealed by introducing appropriate boundary conditions and/or initial qualifications. The evolutional properties of the complex wave excitations are briefly investigated.     

A New Type of Conserved Quantity Deduced from Mei Symmetry for Relativistic Mechanical System in Phase Space

In this paper, a new type of conserved quantity indirectly deduced from the Mei symmetry for relativistic mechanical system in phase space is studied. The definition and the criterion of the Mei symmetry for the system are given. The condition for existence and the form of the new conserved quantity are obtained. Finally, an example is given to illustrate the application of the results.     

Magneto-resistance and vortex phase diagram of BaNi_（0.1）Fe_（1.9）As_2 single crystal

The transition from vortex glass to a liquid phase is studied in Ba Ni0.1Fe1.9As2 single crystal with Tc = 19.4 K by magneto-resistance measurements. The resistivity curves are measured in magnetic fields in a range of 0 T–13 T for H‖c and H⊥c. Good scalings for all values of resistivity ρ（H, T） and the effective pinning potential U0（H, T） are obtained with the modified vortex glass theory by using the critical exponents s and H0. Phase diagrams for H‖c and H⊥c are determined based on the obtained vortex glass temperature Tg, the vortex dimensionality crossover temperature T＊, and the upper critical magnetic field Hc2. Our results suggest that both below and above 5 T, single vortex pinning co-exists with collective creep, and collective creep is dominant. There is a narrower vortex liquid region for H⊥c than for H‖c in the vortex phase diagram, which may originate from a stronger pinning force.     

Entropy Exchange and Entanglement in Superconducting Charge Qubit Inside a Resonant Cavity with Intrinsic Decoherence

By considering the intrinsic decoherence effect, we investigate the entropy exchange and entanglement in the interacting system of a superconducting charge qubit coupled to a single-mode optical cavity. We found that although the intrinsic decoherence leads to an irreversible evolution of the interacting system due to a suppression of coherent quantum features through the decay of off-diagonal matrix elements of the density operator, and has an apparently influence on the partial entropies of the two-component subsystems, it dose not destroy entropy exchange behavior. In addition, the lower bound of the concurrence, as the measure of entanglement of the coupling system, is calculated. It is shown that the evolution of entanglement is sensitive to the change of the intrinsic decoherence.