bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical research on cascaded difference frequency generation of terahertz radiation
Authors: Zhong Kai  , Yao Jian-Quan  , Xu De-Gang  , Zhang Hui-Yun  , Wang Peng  ,   Institute of Laser and Optoelectronics, College of Precision Instrument and Optoelectronic Engineering, Tianjin University, Tianjin 300072, China
Published: December 2020

A novel mechanism of cascaded difference frequency generation (DFG) is advanced in this article to solve the problem of low-efficiency in terahertz (THz) DFG. The cascaded DFG process is theoretically analyzed using ZnTe crystal as an example. The optimal pumping condition and crystal length is obtained, and the effects of crystal absorption, wave number mis-match and pumping intensity are investigated by solving the coupling wave equations of cascaded DFG. It is obviously seen from the calculation results that the terahertz conversion efficiency can be greatly enhanced in cascaded DFG, in which the photon conversion efficiency can even break through the Manley-Rowe limit.
The application of symplectic geometric algorithm in a special Chaplygin system
Authors: Wang Zhong-Wen  , Guo Yong-Xin  , Liu Shi-Xing  , Liu Chang  , Chang Peng  ,   (1)College of Physics, Liaoning University, Shenyang 110036, China; (2)School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China
Published: December 2020

A special Chaplygin system is studied numerically by using the symplectic geometric algorithm and compared with the classical R-K method. By comparing the results of the two methods, the advantage of symplectic geometric algorithm used on this special Chaplygin mechanical system is demonstrated.
Phase investigation on relativistic klystron amplifier
Authors: Huang Hua  , Guo Yan-Hua  , Jin Xiao  , He Hu  , Lei Lu-Rong  , Luo Xiong  , Chang An-Bi  , Li Zheng-Hong  ,   Institute of Applied Electronics, CAEP, Mianyang 621900, China
Published: December 2020

The relevant facts to phase of relativistic klystron amplifier (RKA) are analyzed in this paper. The output microwave phase of RKA relevant to voltage, current, size, rising time and delay time of electron beams is simulated by PIC. It is found that the phase shift of RKA is changed with the voltage, current and size of electron beams. On the contrast, the leading magnetic field, rising time and delay time of electron beams do not change the phase shift of RKA obviously. The phase of RKA is investigated in experiment too. The phase sensitivity of RKA is about 2.6 degrees; the phase shaking of RKA is less than 20 degrees. The experimental results are content well with the simulations.
Influence of spin-coating rate and annealing method of water-soluble CuPc on blue organic light-emitting devices performance
Authors: Gao Li-Yan  , Zhao Su-Ling  , Xu Zheng  , Zhang Fu-Jun  , Sun Qin-Jun  , Zhang Tian-Hui  , Yan Guang  , Xu Xu-Rong  ,   Institude of Optoelectronics Technology, Beijing Jiaotong University, Key Laboratory of Luminescence and Optical Information (Beijing Jiaotong University), Ministry of Education, Beijing 100044,China
Published: December 2020

Investigated in this work are the effects of the spin-coating rate of water-soluble copper phthalocyanine (WS-CuPc) and the annealing method of WS-CuPc films obtained at the optimal spin-coating rate on the performances of blue organic light-emitting devices (OLEDs). The OLEDs, eack with a configuration of ITO/WS-CuPc/NPB/Be(PP)2/LiF/Al, are fabricated by using WS-CuPc as hole injection layer, NPB as hole transport layer and Be(PP)2 as emission layer separately. In our experiments, a new annealing method of WS-CuPc is used first for heating the ITO glass, and then for spin-coating the WS-CuPc. The performances of the device prepared with the new annealing method are compared with those of the devices prepared with the traditional annealing method or no annealing treatment. And the effects of different annealing treatments on the surface topography are analyzed by atomic force microscope (AFM). The experimental results demonstrate that there exists an optimal spin-coating rate of WS-CuPc, about 3000 r/min. Based on the optimal spin-coating rate of WS-CuPc, the roughness of the film prepared with the new annealing method is lowest and the performances of the device are best.
The electrical transport properties of Ag/Nd0.7Sr0.3MnO3 ceramic interface
Authors: Medvedeva I  , Chen Shun-Sheng  , Huang Chang  , Wang Rui-Long  , Yang Chang-Ping  ,   (1)State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China; (2)The Provincial Key Laboratory of Piezoelectric Ceramics Materials and Apparatus, Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062, China
Published: December 2020

The transport properties of interface between metal electrode and Nd0.7Sr0.3MnO3 bulk have been investigated under 2-wire measuring mode using permeating Ag and Ag-glue contact, respectively. The results show that, for the permeating Ag contact, the measured results are similar to that of 4-wire measurement, and an ohmic character is obtained without EPIR effect. However, a strongly nonlinear V-I curve appears and exhibits a stable EPIR effect for the Ag-glue contact. Besides, It also shows remarkable difference when loaded with alternating current for the two different kinds of contacts. For the former, the real part of impedance R' increases with increasing frequency which is attributable to the skin effect; for the latter, however, the R' is of about megohm order of magnitude and the R' peak decreases with increasing frequency. Moreover, the R' peak splits into two peaks which respectively move to high and low temperature when further increasing the frequency. In combination with the data of scanning electron microscopy, the differences of electrical transport are discussed.
Stability and magnetism of fcc single-crystal nickel nanowires by first principles calculations
Authors: Cheng Zhi-Da  , Zhu Jing  , Sun Tie-Yu  ,   Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
Published: December 2020

The stability and magnetism in fcc single-crystal nickel nanowires with low-index axial direction are studied by first principles methods in this work. For fcc nickel nanowires, it is found that [110] is the most stable direction, while [111] is less stable and [001] the least stable. Nickel nanowires can be described by a simple core-shell model. The core atoms of nanowires have almost the same magnetic moment as in bulk metal. Surface atoms of nickel nanowires have larger atomic magnetic moments in varying degrees related to axial direction. In our calculated nanowires with low-index axial directions, surface atoms in [110] nanowires have lowest magnetic moments while those in [100] nanowires have the largest.
Preparation and luminescent properties of SrMoO4:Eu3+phosphor for light emitting diode
Authors: Tang Hong-Xia  , Lü Shu-Chen  ,   Department ofPhysics and Electronic Engineering Harbin Normal University, Harbin 150080,China
Published: December 2020

The SrMoO4:Eu3+red phosphors that can be excited effectively by the ultraviolet, near ultraviolet and blue light emitting diode (LED) were prepared by chemical coprecipitation. The crystal structure and luminescent properties of the SrMoO4:Eu3+ phosphors were investigated. The X-ray diffraction patterns showed that the SrMoO4:Eu3+synthesized by the process was a pure phase with tetragonal structure. The excitation spectrum of the SrMoO4:Eu3+red phosphors consisted of a broad band peak and a series of sharp peaks, and since the strong peaks were located at 280 nm (the broad band center), 395 nm and 465 nm, respectively, the phosphor can be excited effectively by the UV LED and Blue LED. The emission spectrum excited by 395 nm showed a strong emission peak at 613 nm, originating from the 5D0→7F2transition of Eu3+ions. The Eu3+ion concentration has great influence on the crystal parameters, the crystal symmetries and the luminescent properties. The influence of different concentrations of doped Eu3+ions on the luminescent intensity of SrMoO4:Eu3+was studied and the optimal doping concentration was found to be 15%.
Investigation of luminescence properties of basal plane dislocations in 4H-SiC
Authors: Miao Rui-Xia  , Zhang Yu-Ming  , Tang Xiao-Yan  , Zhang Yi-Men  ,   School of Microelectronics, Xidian University, Key Laboratory for Wide Band-Gap Semiconductor Materials and Devices, Xi’an 710071, China
Published: December 2020

Luminescence properties of basal plane dislocations in 4H-SiC are studied by means of cathodoluminescence(CL) and defect selective etching. It is found that basal plane screw dislocations (BTSD) and basal plane mixed dislocations (BMD) have green and blue-green luminescence properties, respectively. The spectrum peaks near 530 nm and 480 nm correspond to BTSD and BMD,respectively. It is found from measurement that the luminescence peak from BMD is blue-shifted. The atoms of BTSD near the dislocation core are affected by tensile stress along the Burger’s vector direction, leading to its band gap narrowed. In addition, the Burger’s vector of BMD has both screw and edge components. It is the edge component that is responsible for the band gap broadening. In other words, the wavelength from BMD is shorter than that from BTSD.
Finite size effect of the ballistic depositionmodel with shadowing
Authors: Hao Da-Peng  , Tang Gang  , Xia Hui  , Han Kui  , Xun Zhi-Peng  ,   Department of Physics,China University of Mining and Technology,Xuzhou 221116,China
Published: December 2020

The model of ballistic deposition (BD) with shadowing means that the tilt incidence of particles in a certain angle of distribution is taken into account based on the BD model. In this paper,in order to investigate the finite size effect and the scaling properties of the BD with shadowing,the extrapolation method is used to determine the asymptotic scaling exponents of the model in the large-size limit. The simulation results illustrate that the finite size effect on BD with shadowing is different from that on BD, and the shadowing as a nonlocal interation can significantly change the scaling properties of BD model.
Emergence of local structures in complex network:common neighborhood drives the network evolution
Authors: Cui Ai-Xiang  , Fu Yan  , Shang Ming-Sheng  , Chen Duan-Bing  , Zhou Tao  ,   (1)Web Sciences Center, University of Electronic Science and Technology of China, Chengdu 611731, China; (2)Web Sciences Center, University of Electronic Science and Technology of China, Chengdu 611731, China;Department of Morden Physics, University of Science and Technology of China, Hefei 230026, China
Published: December 2020

After extensive study on the small-world and scale-free properties of networks, the research focus is shifting to detailed local structures. Empirical analysis shows that many real networks exhibit the power-law clique-degree distribution. This general regularity cannot be produced by the rich-get-richer mechanism. In this paper, we propose a common-neighborhood-dirven model in which the observed power-law clique-degree distribution con be well reproduced, indicating that the common-neighborhood-dirven mechanism is an essential factor leading to the emergence of local structures.
Numerical research of signal-to-noise ratio gain on a monostable stochastic resonance
Authors: Wan Pin  , Zhan Yi-Ju  , Li Xue-Cong  , Wang Yong-Hua  ,   (1)Faculty of Automation, Guangdong University of Technology, Guangzhou 510006, China; (2)School of Engineering, Sun Yat-Sen University, Guangzhou 510006, China
Published: December 2020

We report a stochastic resonance with the signal-to-noise ratio gain in a monostable system, by the fourth-order Runge-Kutta method, and on some occasions the signal-to-noise ratio gain exceeds 1. Tuning the parameters in the monostable stochastic resonance system can change the signal-to-noise ratio gain. This research result is the latest development of the monostable stochastic resonance, and has potential applications in the signal detection, processing and communications.
Projective synchronization for unified hyperchaotic system
Authors: Abdurahman Kadir  , Wang Xing-Yuan  , Zhao Yu-Zhang  ,   (1)Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024, China; (2)Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024, China;School of Computer Science and Engineering, Xinjiang University of Finance and Economics, Urumchi 830012, China; (3)School of Computer Science and Engineering, Xinjiang University of Finance and Economics, Urumchi 830012, China
Published: December 2020

The projective synchronization in the unified hyperchaotic system using two control method is studied in this paper. Based on the Lyapunov stability theory, the full state hybrid projective synchronization is achieved via an adaptive controller. It is proved theoretically that the controller can make the states of the dynamical system and the response system with known parameters achieve the asymptotically full state hybrid projective synchronization. An active controller is designed to achieve the projective synchronization. Finally, Numerical simulations show the effectiveness of the two schemes.
Effect of deuterium ion beam bombarding time oncharacteristic of deuteride titanium target
Authors: Wang Bo-Yu  , Xiang Wei  , Dai Jing-Yi  , Tan Xiao-Hua  , Cheng Liang  , Chen Lei  , Qin Xiu-Bo  ,   (1)Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang 621900, China; (2)Key Laboratory of Nuclear Analysis Techniques, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Effect of the deuterium ion beam bombarding time on characteristic of the deuteride titanium target is studied by measuring the neutron yield as a function of bombarding time with the associated-particles method in ZF-300 neutron generation. Slow positron annihilation spectroscopy for defect structure analysis and scanning electron microscopy for the surface morphology analysis are used to characterize the targets. The results show that the beam bombardment cause the changes of the defect structure and the surface morpholoy of the deuteride titanium target, but the different bombarding times do not lead to the changes of the neutron yield, the defect structure, and the surface morphology of the deuteride titanium target under the work condition. The prominent physical mechanism of the interaction between deuterium ion beam and deuteride titanium target is discussed in detail based on the numerical study of the interaction between beam and solid.
Terahertz radiations from narrow band gap of semiconductor irradiated by femtosecond pulses with different pump intensities
Authors: Zhao Guo-Zhong  , Wang Xin-Qiang  , Wang Hai-Yan  ,   (1)Key laboratory of THz Optoelectronics of Ministry of Education, Departments of Physics, Capital Normal University, Beijing 100048,China; (2)State Key Laboratory of Artificial Microstructure and Macroscopic Physics, School of Physics, Peking University, Beijing 100871, China
Published: December 2020

The characteristics of terahertz (THz) radiations from the surfaces of two kinds of narrow-band semiconductors InN and InAs excited by femtosecond laser pulses with different pump powers (from 10 to 320mW) are investigated experimentally. The results show that InAs can irradiate a stronger THz signal than that of InN under the same pump power so its radiation efficiency is higher. However, the spectral widths of THz radiations from these semiconductor surfaces increase with the increase of pump power. When the intensity of pump laser is high enough, the spectral Half-Maximum-Full-Width (HMFW) of THz radiation tends to be a constant. Compared with InAs, InN can reach this constant HMFW THz spectrum at a lower pump power. This research is significant for investigating the THz radiation mechanism from semiconductor surfaces, and it is also a good reference for exploring a THz radiation source with low cost and high efficiency.
Study on vibrational excitation cross sections of low-energy electrons scattering from H2 molecule including exact exchange
Authors: Li Yong-Jun  , Feng Hao  , Sun Wei-Guo  , Zeng Yang-Yang  , Wang Xiao-Lian  , Li Hui-Dong  , Fan Qun-Cao  ,   (1)Institution of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China; (2)Research Center for Advanced Computation, School of Physics and Chemistry, Xihua University, Chengdu 610039, China
Published: December 2020

Elastic and inelastic differential and integral cross sections for low-energy vibrational excitation of H2 by electron impact are studied with exact exchange. The resulting coupled integrodifferential equations are solved using a combination of linear-algebraic and R-matrix-propagator techniques. The converged (0→0,0→1,0→2) differential and integral cross sections are obtained. The calculated results are in good agreement with experimental resalts and other calculations, showing that the exact exchange based on equations of vibrational close coupling plays an important role in low-energy electron scattering from H2 molecule.
Theoretical study of nonlinear electromagnetically induced absorption in four-level atomic system
Authors: Wang Li  , Lu Cheng  ,   College of Physics and Electronics Engineering, Nanyang Normal University, Nanyang 473061, China
Published: December 2020

In the n-type four-level atomic system, we have studied the nonlinear theory of electromagnetically induced absorption. The results show that the probe light Rabi frequency and the attenuation distribution coefficient A affect the nonlinear absorption and then the absorption of a medium. When the probe light intensity is weak, the absorption of the medium and the linear absorption are the same, showing the characteristics of electromagnetic induction absorption. When the probe light intensity is increased, the absorption of the medium and the linear absorption are no longer the same, and now the medium absorption curve will show hole burning phenomenon, and then it will show the gain phenomenon. At the same time, the nonlinear absorption is affected by the value of A. Even if the probe light is weak, the medium absorption will change the electromagnetic induction absorption into the gain phenomenon with the A value decreasing.
Investigations on chaos synchronization characteristics of mutually coupled semiconductor lasers with asymmetrical bias currents
Authors: He Yuan  , Deng Tao  , Wu Zheng-Mao  , Liu Yuan-Yuan  , Xia Guang-Qiong  ,   School of Physics, Southwest University, Chongqing 400715, China
Published: December 2020

Based on a delayed mutually coupled system consisting of two semiconductor lasers (SL) with different injection currents, the influences of the asymmetric bias currents of two SLs and the frequency detuning Δf (Δf=f1-f2, where f1 and f2 are the free frequencies of SL1 and SL2 respectively) on synchronization performance have been investigated experimentally. The results show that for the case of the two SLs with identical free oscillation frequencies, the mutually coupled system can achieve excellent chaos synchronization under relatively large asymmetrical injection currents. Furthermore, the frequency detuning, controlled by adjusting the temperature of one of the two SLs, has an obvious influence on synchronization performance. For the case of the SL1 biased at a relatively much larger current than that of SL2, the synchronization performance will degrade with the increase of the positive frequency detuning (f1>f2), while the synchronization performance can be further improved with suitable negative frequency detuning. The simulated results are basically consistent with experimental results.
Adsorption efficiency of cesium in activation process for GaAs photocathode
Authors: Niu Jun  , Zhang Yi-Jun  , Chang Ben-Kang  , Xiong Ya-Juan  ,   School of Electronic Engineering and Optoelectronic Technology, Nanjing University of Science and Technology, Nanjing 210094, China
Published: December 2020

Photocathode materials with the lower surface doping density need a longer time to raise photocurrent in the first Cesium activation process when the system vacuum level is not high enough, which can be found from the photocurrent curves during the activation of negative-electron-affinity (NEA) GaAs photocathodes. At the same time, with the enhancement of system vacuum level, these differences in time will become unobvious. It is indicated that the adsorption efficiency of Cesium on cathode surface has the direct relationships with the surface doping density and system vacuum level. In order to analyze these relationships quantitively, in this paper, a mathematical model of the adsorption efficiency of Cesium on cathode surface is established according to the experimental data. The simulation results by the model are in good accordance with the experimental phenomenon. This study is of very important value and significance for the further investigation of structure design and preparation techniques for varying doping GaAs photocathode materials.
Enhanced third order nonlinear optical property of a side-chain conjugated thiophene copolymer
Authors: Hou Chao-Qi  , Gao Chao  , Qiu Shao-Jun  , Yang Zhao-Fei  , Du Wei-Song  , Guo Hong-Yan  ,   (1)State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences (CAS), Xi’an 710119,China; (2)Xi’an Modern Chemistry Research Institute, Xi'an 710065, China
Published: December 2020

A novel side-chain conjugated polythiophene copolymer with a narrow band gap of 1.72eV, poly -thiophene (POTVTh-Th), is synthesized by the Stille coupling reaction. The third order nonlinear optical properties of the copolymer are measured by femtosecond Z-scan technique at 800nm. The results indicate that the third order nonlinear susceptibilities of the polymer solution and the film are 8.84×10-10esu and 7.25×10-9esu, respectively, which are 2.17 and 1.68 times bigger than those of its homopolymer, showing enhanced third order nonlinear optical properties and the good nonlinear optical properties of this side-chain conjugated copolymers.
Effect of bandgap engineering on thermal characteristic of radiofrequency power SiGe heterojunction bipolar transistor
Authors: Xiao Ying  , Zhang Wan-Rong  , Jin Dong-Yue  , Chen Liang  , Wang Ren-Qing  , Xie Hong-Yun  ,   College of Electronic and Control Engineering, Beijing University of Technology, Beijing 100124, China
Published: December 2020

As is well known, direct-current (DC) characteristic, frequency characteristic and noise characteristic of SiGe heterojunction bipolar transistor(HBT) can be improved by "bandgap engineering"(by Ge composition). However, the effect of "bandgap engineering" on the thermal characteristic of HBT has not been reported. In this paper, the effect of "bandgap engineering" is analyzed by the use of 3D thermal-electric feedback model. Considering the temperature dependence of emitter junction voltage and current gain, the expression of the minimum emitter ballasting resistance (REmin), which is necessary for SiGe HBT thermal stability, is presented. Furthermore, non-uniform ballasting resistance design is given so as to further enhance the thermal stability of device. It is found that the surface temperature of the device decreases with the increase of Ge composition in SiGe base. This is because SiGe HBT internally possesses the thermal-electrical negative feedback. For the same dissipated power, the REmin decreases as Ge composition increases, which is beneficial to the improvment of the performance of radio frequancy(RF) power SiGe HBT. These results provide a good guide to further optimization of RF power SiGe HBT performance, especially thermal design.
A complete symmetric solution for trichromatic tri-directional surface capillary-gravity waves with uniform currents in water of finite depth
Authors: Huang Hu  , Xia Ying-Bo  ,   Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China
Published: December 2020

Making a basic description of a typical characteristic of multichromatic multidirectional ocean surface waves and taking into account widespread wave-current interactions and the rich effects of capillary waves, a complete symmetric solution of trichromatic tri-directional waves in water of finite depth is presented, leading to a sufficient inclusion of and a centralized reflection of the existing monochromatic and multichromatic multidirectional wave theories.
Enhancement of ion generation in low-contrast laser-foil interactions by defocusing
Authors: Li Yu-Tong  , Liu Feng  , Zhang Yi  , Lin Xiao-Xuan  , Wang Shou-Jun  , Wang Zhao-Hua  , Li Ying-Jun  , Sheng Zheng-Ming  , Xu Miao-Hua  , Wei Zhi-Yi  , Zhang Jie  , Zheng Jun  , Meng Li-Min  ,   (1)Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; (2)Department of Physics, China University of Mining & Technology (Beijing), Beijing 100083, China; (3)Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 China
Published: December 2020

The characteristics of proton beams generated from ultra-intense laser-foil interactions under varied focal offsets are experimentally studied on XL-Ⅱ laser facility.The experimental results show that when strong femtosecond prepulses are presented before the main pulse, the conversion efficiency from the laser energy to the protons is enhanced by 3 orders of magnitude with effective improvement of the beam collimation by properly defocusing the laser pulses. The depression of the prepulse effect on the proton acceleration is believed to be one of the main reasons for the significant optimization. Besides, the particle-in-cell (PIC) simulation results indicate that the population of moderate energy electrons increases under large focal offsets, which in turn effectively improves the acceleration electric field and the beam quality.
Performance optimization of global interconnect basedon dual supply and dual threshold voltages
Authors: Dong Gang  , Liu Jia  , Xue Meng  , Yang Yin-Tang  ,   Key Laboratory of Ministry of Education for Wide Band-Gap Semiconductor Materials and Devices,Microelectronics Institute, Xidian University, Xi'an 710071
Published: December 2020

Based on dual supply and dual threshold voltages technique, a novel methodology optimizing global interconnect performance in presented in this paper. The new figure of merit (FOM) is first defined as a function of bandwidth, delay and power consumption of global interconnect. Then, the optimal dual voltages can be obtained to save interconnect power by maximizing FOM function within a given delay penalty. Simulations show that in 65 nm technology, for the allowed delay penalties of 5%, 10% and 20%, the proposed methodology saves 27.8%, 40.3% and 56.9% power compared with the case with single supply and single threshold voltages, respectively. It can also be found that more power savings are achieved with the technology improving. The proposed methodology can be used to design and optimize global interconnects.
Thermal release of helium in materials inducedby random-walk mechanism
Authors: Li Ren-Shun  , Zhou Yu-Lu  , Zhang Bao-Ling  , Deng Ai-Hong  , Hou Qing  ,   (1)Department of Physics, Sichuan University, Chengdu 610064, China; (2)Key Laboratory for Radiation Physics and Technology Ministry of Education, Institute of NuclearScience and Technology, Sichuan University, Chengdu 610064, China
Published: December 2020

Based on the theory for random-walk with an absorption wall, the characteristics of thermal release of helium in materials are studied. The influences of the initial depth distribution and the diffusion coefficient of helium in materials on the thermal release are investigated. A comparison is made between the thermal releases induced by the random-walk mechanisms and the thermal desorption mechanisms. It is pointed out that the initial depth distribution and the states that Helium atoms stay in are required for the correct understanding of experimental observations of thermal releases of helium in materials.
Densities of states of strained Si in different crystal systems
Authors: Song Jian-Jun  , Zhang He-Ming  , Dai Xian-Ying  , Xuan Rong-Xi  , Hu Hui-Yong  , Wang Guan-Yu  ,   Key Lab of Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xian 710071, China
Published: December 2020

There has been aroused a lot of interest in the strained Si technology in the microelectronic field. Density of states (DOS) is an important physical parameter in strained Si materials. Based on the Kleinerts Variational perturbation (KP) theory related to stress, DOSs of electrons and holes near the bottom of conduction band and the top of valence band are obtained in tetragonal, rhombohedral and monoclinic strained Si grown from (001), (101) and (111) substrates respectively. It is found that their DOSs are obviously different from the ones of cubic unstrained Si, except DOSs of electrons near the bottom of conduction band in rhombohedral and monoclinic strained Si. The quantized model obtained can provide valuable references for understanding the strained Si material physics and developing the theoretical model of the other important physical parameters.
Noise as a characteriscic for current transmitting rateof optoelectronic coupled devicesfor ionization radiation damage
Authors: Bao Jun-Lin  , Lin Li-Yan  , He Liang  , Du Lei  ,   (1)Microelectronic Institute, Xi dian University, Xian 710071, China; (2)School of Technology Physics, Xi dian Universit y, Xian 710071, China
Published: December 2020

Based on the mechanism of ionization radiation damage in optoelectronic coupled devices (OCDs), the characteristic models of current transmitting rate (CTR) and 1/f noise are established. The results show that CTR degradation and noise increase are due to the increase of SiO2/Si interface defects at the collector junction and emit junction in phototransistor. The relationship between CTR degradation and noise change is established by the radiation dose. The correctnesses of characteristic models are validated in experiment. By the relationship between noise change and radiation dose, the high-dose radiation degradation can be predicted through the low-dose irradiation experiment. So noise can be used to evaluate the radiation tolerance of OCDs.
Density-functional theory investigation of atomic geometryand oxygen adsorption of Au(110) surface
Authors: Wang Mang-Mang  , Ning Hua  , Tao Xiang-Ming  , Tan Ming-Qiu  ,   Department of Physics, Zhejiang University, Hangzhou 310027, China
Published: December 2020

We have performed density-functional theory calculations of the atomic structure and the oxygen adsorption properties of Au(110) surfaces. The relaxations of missing-row reconstructed Au(110)-(1×2) surface are calculated to be -15.0%(Δd12/d0) and -1.1%(Δd23/d0). The relevant surface energy and workfunction are calculated to be 52.7 meV/2 and 5.00 eV, respectively. In the case of missing-row reconstructed Au(110)-(1×3) surface the surface atomic relaxations are calculated to be -20.5 %(Δd12/d0) and +2.7 %(Δd23/d0) which are quite differente from those of Au(110)-(1×2). However, in the later case, the surface energy and workfunction are found to be very close to those of missing-row reconstructed Au(110)-(1×2) surface, i.e., 53.4 meV/2 and 4.98 eV. We have simulated the scanning tunneling microscope (STM) images of both reconstructed surfaces and found that the missing row exhibits a remarkable hollow in the STM morphology. The further calculation of oxygen adsorption on both surfaces reveals that the adsorption energies in these cases are negative. These results indicate that the Au(110) surface is free from oxygen adsorption and reaction, showing highly chemical inertia.
Effects of p and n pillar widths on electrical characteristicsof super junction SiGe power diodes
Authors: Ma Li  , Wang Dong-Fang  , Gao Yong  , Zhang Ru-Liang  ,   (1)Department of Applied Physics, Xi’an University of Technology, Xian 710048, China; (2)Department of Electronics Engineering, Xi’an University of Technology, Xian 710048, China
Published: December 2020

By combining merits of both SJ structure and SiGe material, a novel super junction (SJ) SiGe power diode is presented. The two important characteristics of SJ SiGe diode are its columnar structure of alternating p/n pillars substituting n- base region of conventional Si p+n-n+ diode and its far thinner strained SiGe p+ layer, which can overcome the drawbacks of conventional Si power switching diodes, such as when the reverse blocking voltage is higher, the forward voltage drop is larger and the reverse recovery time becomes longer. For the SJ SiGe diode with 20% Ge content, the following conclusions can be obtained compared with comparable conventional Si power diodes: the breakdown voltages increase by 1.6 times, the forward voltage drop is reduced by 60 mV (at a current density of 10 A/cm2) and the softness factor S increases by 2 times. Though the reverse recovery time is shortened slightly, the peak reverse current density decreases by 17% and the soft recovery characteristics is improved notedly. The key parameters of the p and n pillar widths have imporant effects on the forward conduction characteristic, reverse blocking characteristic and reverse recovery characteristic of SJ SiGe power diode. The smaller the pillar width becomes, the higher the breakdown voltage is and the lower the reverse leakage current is, whereas the forward voltage drop increases slightly. The pillar width has no obviously monotonic effect on the reverse recovery characteristic. If the width is too small, the soft reverse recovery characteristic is degenerated. To optimize the parameter of pillar width, we can obtain excellent SJ SiGe diode with fast recovery speed, high breakdown voltage and low forward drop at the same time.
Theoretical study of inelastic current in molecularnano-junction excited by infrared field
Authors: Zhang Yuan  , Wang Lu-Xia  ,   Department of Physics, School of Mathematics and Physics, University of Science and Technology of Beijing, Beijing 100083, China
Published: December 2020

Molecular nano-junction is modeled by 'metal/single molecule/metal’ structure. With the generalized master equation method, the inelastic current induced by the sequential charge transmission through the junction is studied under the excitation of infrared fields in the case of weak lead-molecule coupling.The interaction between infrared field and molecule is described with the models of exponential coupling, square coupling, and linear coupling respectively. In the excitation of varieties of infrared fields, the inelastic current-voltage characteristics and the effects of intramolecular vibrational energy redistribution are discussed.
Comprehensive Survey for the Frontier Disciplines
Authors: Yang Yang  , Chen Shu-Fen  , Xie Jun  , Chen Chun-Yan  , Shao Ming  , Guo Xu  , Huang Wei  ,   Key Laboratory for Organic Electronics & Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications (NUPT), Nanjing 210046, China
Published: December 2020

Organic light-emitting device (OLED) technology shows tremendous commercial applications in communication, information, display, and lighting. It has been one of the most attractive projects in optoelectronic information field over the last decade. However, the internal efficiency is quite different from the external efficiency, and to some extent, a low external efficiency restrictes the development and application of OLEDs. The light out-coupling has been improved by a number of different techniques through the modification of device architecture. In this paper we present various light out-coupling techniques that have been implemented to enhance the external efficiency of OLEDs. Various OLED device modification techniques, e.g., micro-lens array, photonic crystal structure, nano-patterned and nanoporous films, and microcavity technique, have been reviewed and discussed. Finally, some perspectives on light out-coupling techniques are proposed.
Analysis of low-frequency oscillation phenomenon in the pulsetrain controlled buck converter
Authors: Wang Jin-Ping  , Xu Jian-Ping  , Zhou Guo-Hua  , Mi Chang-Bao  , Qin Ming  ,   School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China
Published: December 2020

In this paper, the low-frequency oscillation phenomenon in a pulse train (PT) controlled buck converter operating in continuous conduction mode (CCM) is found and studied. The mechanism of this low-frequency oscillation phenomenon and the way to suppress it are studied. The time-domain simulation results and their corresponding phase portraits indicate that the equivalent series resistance (ESR) of the output filter capacitor has a critical effect on this low-frequency oscillation phenomenon. When the ESR is zero or small enough, such a low-frequency oscillation phenomenon appears in the PT controlled CCM buck converter because the output voltage can not be regulated timely. With the increase of ESR, the PT controlled CCM buck converter operates chaotically. The output voltage can be regulated timely and such a low-frequency oscillation phenomenon can be suppressed effectively. Experimental results are provided to verify the theoretical analyses and the simulations.
High power microwave pulse compression systembased on cylindrical resonant cavity
Authors: Fang Jin-Yong  , Huang Hui-Jun  , Zang Zhi-Qiang  , Huang Wen-Hua  , Jiang Wei-Hua  ,   (1)Department of Electrical Engineering, Tsinghua University, Beijing 100084, China; (2)Northwest Institute of Nuclear Technology, Xian 710024, China
Published: December 2020

High power microwave (HPM) pulse compression is a main method to obtain high power microwave with non-relativistic devices. The mature HPM pulse compression systems are nearly all based on rectangular resonant cavity, and the pulse compression systems based on cylindrical resonant cavity are in progress. A new type pulse compression system based on cylindrical resonant cavity is proposed in this paper, and the structure of the system is different from those of all other HPM pulse compression systems ever reported. The structure and the numerical simulation results of the key parts are presented, and a preliminary analysis of the power capability of the system and the quality factor of the resonant cavity is also given. For a pulse compression system, the power capacity is a key factor for the output microwave pulse power, and the quality factor of the resonant cavity has a close relationship with the system energy efficiency. According to the experimental results, the pulse capacity of the pulse compression system based on cylindrical resonant cavity can be 10 times higher than that of the systems based on the rectangular resonant cavity, and the quality factor of the resonant cavity can be improved by a factor of 5.
Influence of charge cloud size on performance of UV photon-counting imaging detector
Authors: Liu Yong-An  , Yan Qiu-Rong  , Sheng Li-Zhi  , Zhao Fei-Fei  , Hu Hui-Jun  , Zhao Bao-Sheng  ,   (1)State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710119,China; (2)State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710119,China;Graduate University of Chinese Academy of Sciences, Beijing 100049,China
Published: December 2020

The size of charge cloud is examined as a function of acceleration voltage, distance between MCP and anode, and MCP gain. The performance of photon counting imaging detector is significantly affected by charge cloud size. In this paper, the influence of charge cloud size on the performance of UV photon-counting imaging systems is investigated. Modulation distortion, "S" distortion and their cause are discussed. Then, Monte Carlo simulations for anode decode with different charge cloud sizes are carried out. And finally, the effects of acceleration voltage, distance between MCP and WSA, and MCP gain on the system performance are tested and some practical solutions of modulation and "S" distortion are suggested.
Travelling wave solution of the weakly nonlinear evolution equation with control term
Authors: Mo Jia-Qi  , Cheng Rong-Jun  , Ge Hong-Xia  ,   (1)Department of Mathematics, Anhui Normal University, Wuhu 241003, China; (2)Faculty of Science, Ningbo University, Ningbo 315211, China; (3)Ningbo Institute of Technology, Zhejiang University, Ningbo 315100, China
Published: December 2020

A weakly nonlinear evolution equation with control term is considered using the analytic method. From the perturbation theory, the solution of the corresponding equation is obtained. And the functions of asymptotic solution for the equation are studied.
A sine-Gordon soliton star model with the action of exotic matter and dark energy
Authors: Li Ji-Gen  , Yan Jun  , Zou Bo-Xia  , Su Wen-Jie  ,   Department of Physics, Sichuan Normal University, Chengdu 610066,China
Published: December 2020

A sine-Gordon soliton star model with the action of exotic matter and dark energy is studied in this article, the solutions of state equation and mass of star are calculated by using field equation. We found that the density and pressure of matter are connected with the soliton state and the mass of star. Moreover, star equilibrium and stability of dark energy are analyzed and discussed, the result shown that the state of soliton star interior exist in the form of mixed state.
Multiple quadrate soliton solutions and chaotic behaviours of (2+1)-dimensional breaking soliton equation
Authors: Lei Jun  , Ma Song-Hua  , Fang Jian-Ping  ,   Department of Physics,Zhejiang Lishui College,Lishui 323000, China
Published: December 2020

With the projective equation method and the variable separation method, new exact solutions of the (2+1)-dimensional breaking soliton equation is derived. Based on the derived solitary wave excitation, we obtain multi-quadrate soliton structures with Weierstrassp function and study the chaotic behaviours of the equation for two chaotic systems.
The research of information dissemination model on online social network
Authors: Zhang Yan-Chao  , Liu Yun  , Zhang Hai-Feng  , Cheng Hui  , Xiong Fei  ,   Key Laboratory of Communication and Information Systems-Beijing Jiaotong University, Beijing Municipal Commission of Education, Beijing 100044, China
Published: December 2020

In this paper, we propose a general stochastic model for the information dissemination on the online social network. The model considers the node of degree and propagation mechanism, utilizes complex network theory and dynamics of infectious diseases, and finally establishes the dynamic evolution equations. The dynamic evolution equations describe the evolution process of different types of nodes, and show that the propagation process is influenced by network topology and propagation mechanism. We simulate the information spreading process, and analyze the behavior of different types of nodes on online social network. Simulation results show that information can spread easily on the online social network because of the good connectivity. The greater the degree of the initial spread node, the faster the information spreads on online social network. Center nodes have great social influence, and the nodes with different degrees have the similar trend on online social network. Research shows that the model, having the same characteristics with online social network, contributes to a more profound understanding of information dissemination behavior on online social network.
Sliding mode control of chaotic vibrations of spinning disks with uncertain parameter under bounded disturbance
Authors: Chen Di-Yi  , Shen Tao  , Ma Xiao-Yi  ,   (1)Electric Department of College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, China; (2)Electric Department of College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, China; College of Mechanical and Electric Engineering, Northwest A&F University, Yangling 712100, China
Published: December 2020

In order to eliminate lateral oscillation of spinning disk with uncertain parameter and dispel their adverse effect on the system performance or the working conditions of the system, supposing that the point force acting on the spinning disk is uncertain and bounded, the chaotic complex dynamic characteristics of the four-dimensional nonlinear equations in lateral oscillations of spinning disk under bounded disturbance were analyzed in view of the ubiquity of disturbance, including the space trajectory, the Lyapunov exponent and the Poincaré map. These characteristics enable us to know them deeply, and indicate that the four-dimensional dynamical system contains chaotic attractor. To ensure the robustness of the system control, the author stabilized the chaotic orbits to arbitrary chosen fixed points and periodic orbits by means of sliding mode method, and MATLAB simulations were presented to confirm the validity of the controller. The results show that using sliding mode method can make the system track target orbit strictly and smoothly with short transition time, and its insensitivity to noise disturbance is shown. It provides reference for relevant chaos control in mechanical system.
Multiband fractal cross dipole frequency selective surface
Authors: Wang Shan-Shan  , Gao Jin-Song  , Liang Feng-Chao  , Wang Yan-Song  , Chen Xin  ,   (1)Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics andFine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; (2)Key Laboratory of Optical System Advanced Manufacturing Technology, Changchun Institute of Optics andFine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China; Graduate University of the Chinese Academy of Sciences, Beijing 100049,C
Published: December 2020

Fractal structures has self-similar properties so that they can be applied in the field of frequency selective surface (FSS) as unit cell and the fractal FSS has the nature of simple ,multi-band characteristics on single layer FSS which can be used as spatial pass filters for the incident angle, polarization and the frequency of the electromagnetic wave. Take fractal cross dipole as example, which we can obtain by recursive algorithm and iterative technique, this work gives the expressions of the fractal elements’ geometry and then characterizes the FSS transmission response by the electric field integral equation for the current distribution on the single FSS screen derived from the Floquet's periodic theory unden impedance boundary condition. Genetic algorithm was applied to globally optimize the structure parameters in order to get the design of the double resonant FSS. Finally, FSS sample was prepared by optical lithography and measured in the anechoic chamber. Experimental results show good agreement with the calculations we made for the design of FSS with resonant frequencies 9.2 GHz and 29.4 GHz, which was what we expected from the periodic method of moment.
Atomic structure calculation model based on plasma fluctuation
Authors: Li Xiang-Dong  ,   State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chiness Academy of Sciences, Shanghai 201800, China
Published: December 2020

The new modified Debye-Hückel electron shielding potential, which has been used in the study of fusion cross sections in plasma, is adopted in the atomic structure calculation under plasma environment. By variation of the Tsallis entropic parameter q, the average effect of plasma environment fluctuation is considered in atomic structure of plasma. A calculation using such modified Debye-Hückel potential of the He-like Al shows that the free electron distribution is different between the modified Debye-Hückel model and the linear Debye-Hückel model. This statistic method by considering the plasma fluctuation can also be extended to other plasma screening model, such as the self-consistent ion sphere model.