bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of pre-metallization processing and annealing on Ni/Au Schottky contacts in AlGaN/GaN heterostructures
Authors: Wang Chong  , Feng Qian  , Hao Yue  , Wan Hui  ,   西安电子科技大学微电子研究所，西安  710071；宽禁带半导体材料与器件教育部重点实验室，西安  710071
Published: December 2020

After pre-metallization processing of AlGaN/GaN heterostructure with O2 plasma and HF solution, the Ni/Au Schottky contact characteristics were improved obviously and reverse leakage current reduced by three orders. In addition, annealing experiments were carried out at 200—600℃ for 5min in N2 atmosphere on many batches of Schottky diodes, the reverse leakage current decreased further with annealing temperature increasing. Especially after annealing at 600℃ for 5min in N2 atmosphere, the better uniformity of C-V characteristics at different frequencies indicated that surface trap density was reduced when Ni diffused to AlGaN/GaN surface during annealing. On the other hand, the C-V curves moved to the right and the reduction of absolute value of 2D electron gas depletion voltage proved that the Schottky barrier height was elevated when the annealing temperature increased.
Transverse giant magneto-impedance effect in FeCuCrVSiB single layered and multilayered films
Authors: Wang Wen-Jing  , Yuan Hui-Min  , Jiang Shan  , Xiao Shu-Qin  , Yan Shi-Shen  ,   (1)山东大学物理与微电子学院,济南  250100; (2)山东大学物理与微电子学院,济南  250100；山东大学晶体材料国家重点实验室,济南  250100)
Published: December 2020

Magnetic properties and giant magneto-impedance (GMI) effects of FeCuCrVSiB single layered and multilayered films with Ag as the central layer and SiO2 as the isolating layers, which were prepared by radio frequency sputtering without field and with a magnetic field about 72kA/m along the films length, are investigated. The hysteresis loops of single layered films show that the samples deposited with a magnetic field possess excellent soft magnetic properties and the coercive force is only about 64A/m. After annealing at an optimum temperature of 230℃ for 1.5h, the maximum GMI ratios of single layered films are 37.5% in transverse field at the frequency of 13MHz, and the maximum GMI ratios of multilayered films is 277% at the frequency of 8.6MHz. The frequency dependence of the magneto-impedance indicates that the GMI effect in multilayered films can be very large even at relatively low frequencies.
The element substitution effect of Co in Sr2Fe1－xCoxMoO6 system
Authors: Li Qi  , He Qing  , Wang Hang-Dong  , Yang Jing-Hu  , Du Jian-Hua  , Fang Ming-Hu  ,   浙江大学物理系，杭州  310027
Published: December 2020

The investigations on the structure, magnetic and transport properties were carried out for the double perovskite Sr2Fe1-xCoxMoO6 samples prepared by the solid state reaction method. It is found that the relationship between resistivity and temperature changes from a typical half-metal behavior to a semiconductor behavior, with the increasing substitution concentration x value of Co for Fe. The resistivity at room temperature increases from 3.9×10-5Ω·cm (for the x=0 sample) to 6.0×10-1Ω·cm (for the x=1.0 sample). The magnetic order in the sample changes from a ferrimagnetic to an antiferromagnetic and the magnetic transition temperature TN decreases with the increasing Co content x. The magnetoresistance effect is depressed by the Co partial substitution for Fe. The origin of magnetoresistance and the Co substitution effect were discussed in detail based on the analysis of electronic structure of Sr2Fe1-xCoxMoO6 system.
The breakdown characteristics of ultra-thin gate oxide n-MOSFET under voltage stress
Authors: Ma Xiao-Hua  , Hao Yue  , Chen Hai-Feng  , Cao Yan-Rong  , Zhou Peng-Ju  ,   西安电子科技大学微电子研究所，宽禁带半导体材料与器件教育部重点实验室，西安  710071
Published: December 2020

The characteristics of the TDDB (Time-dependent dielectric breakdown) under the CVS (constant voltage stress) and the gate current model of devices under V-ramp stress were studied in the 1.4nm-thick n-MOSFET. The degradation and failure mechanisms were analyzed. The gate current is produced by the tunneling, the electron surmounting and percolation. During the stress process, the created traps in the oxide not only debase the height of the SiO2 barrier, but also diminish the breadth of the barrier. Every trap engenders a conduction path. These paths enhance the gate current, degrade the device performance and prolong the broken-time of the gate oxide.
Electric field distribution in surface-conduction electron-emitter display
Authors: Li Xin-Bei  , Zhang Fang-Hui  , Wang Xiu-Feng  ,   (1)陕西科技大学 材料科学与工程学院，咸阳  712081; (2)陕西科技大学 电气与电子工程学院，咸阳  712081
Published: December 2020

The surface-conduction electron-emitter display(SED) based on tunneling effect is a newly developed flat panel display. It has obvious technical advantages and excellent characteristics and is praised as one of the most advanced displays. Based on the theory of electromagnetism, an equivalent physical model of a single pixel of SED is established. In particular, it shows the exterior charge densities in different parts of the pixel. Furthermore, the electric potential and electric field intensity are studied in detail, and their distribution is simulated with the help of MATLAB 6.5 Software. Finally, a theoretical analysis of the simulated curved surface is given, and the electrical behavior as well as the emission mechanism is explained comprehensively. In order to further interpret the behavior of electrons in SED, we compare this model with the multi-scattering model and the inertial centrifugal force model respectively. It is found that within the limits of error our conclusion on electric field distribution is consistent with that of the inertial centrifugal force model.
Preparation and characterization of hydrogenated microcrystalline silicon films by HW-MWECR-CVD
Authors: Liu Guo-Han  , Ding Yi  , Zhu Xiu-Hong  , Chen Guang-Hua  , He De-Yan  ,   (1)北京工业大学新型功能材料教育部重点实验室，北京  100022; (2)兰州大学物理科学与技术学院，兰州  730000; (3)兰州大学物理科学与技术学院，兰州  730000；北京工业大学新型功能材料教育部重点实验室，北京  100022; (4)兰州大学物理科学与技术学院，兰州  730000；甘肃省科学院传感技术研究所，兰州  730000
Published: December 2020

Hydrogenated microcrystalline silicon (μc-Si∶H) films with high crystalline volume fraction were deposited using a novel hot wire assisted microwave electron cyclotron resonance-chemical vapor deposition (HW-MWECR-CVD) system. The Raman scattering spectrum and X-ray diffraction measurements were carried out to characterize the microstructure of the films. It was shown that, in a wide range of silane dilution ratio, all the deposited films had high crystalline volume fractions. The transition phase from amorphous to microcrystalline silicon was more easily grown with higher silane dilution ratio, which was attributed to the higher ionization and decomposition of the source gases in HW-MWECR-CVD system than in other systems.
Crystallization of charged colloidal particles: an experimental study
Authors: Liu Lei  , Xu Sheng-Hua  , Liu Jie  , Duan Li  , Sun Zhi-Wei  , Liu Ren-Xiao  , Dong Peng  ,   (1)石油大学(北京)重质油国家重点实验室，北京  102249; (2)中国科学院力学研究所国家微重力实验室，北京  100080
Published: December 2020

Colloidal crystals are fabricated through a self-assembly process of monodispersed polystyrene particles. Evolution of colloidal crystal structures is analyzed by Kossel diffraction technique and UV-Vis spectrophotometer. According to the changes in the Kossel patterns we find the crystal structures change with passage of time and experience successively the following stages: liquid state-random layer structure-stacking disorder structure-fcc with (111) twin-normal fcc structure. The plane distances of different crystal planes and the lattice constants are also determined in this study. The 111 plane distances and the lattice constants evaluated according to the measurement of transmission spectrum are in accordance with the results by the analysis of Kossel line. In addition, it was found that the peaks of the transmission spectrum become sharper and shift considerably toward shorter wavelength during the crystal evolution, showing the lattice constants become smaller.
Sol-gel deposition of highly reflective multilayer coatings from PVP-ZrO2 hybrid systems
Authors: Liang Li-Ping  , Zhang Lei  , Xu Yao  , Zhang Bin  , Wu Dong  , Sun Yu-Han  , Jiang Xiao-Dong  , Wei Xiao-Feng  , Li Zhi-Hong  , Wu Zhong-Hua  ,   (1)中国工程物理研究院激光聚变研究中心，绵阳  621900; (2)中国科学院高能物理研究所同步辐射实验室,北京  100049; (3)中国科学院山西煤炭化学研究所煤转化国家重点实验室,太原  030001; (4)中国科学院山西煤炭化学研究所煤转化国家重点实验室,太原  030001；太原科技大学材料科学与工程学院,太原  030024；中国科学院研究生院,北京  100049; (5)中国科学院山西煤炭化学研究所煤转化国家重点实验室,太原  030001；中国科学院研究生院,北京  100049；中国工程物理研究院激光聚变研究中心，绵阳  621900
Published: December 2020

A series of ZrO2 and polyvinylpyrrolidone (PVP) doped-ZrO2 sols have been synthesized by the controlled hydrolysis and condensation of zirconium n-propoxide, with diethanolamine (DEA) as the chelating agent. PVP-ZrO2 hybrid monolayers and highly reflective (HR) multilayer coatings were then prepared by spin-coating the stable sols on K9 glass substrates. The fabrication of the HR coatings involves alternate depositions of PVP-ZrO2 (as the high-index material) and SiO2 (as the low-index material) layers. The microstructures of the sols, the structural and optical properties, as well as the laser damage resistance of the films were thoroughly characterized. By virtue of the small angle X-ray scattering (SAXS) analysis, the sol-gel processing parameters were successfully optimized, endowing the as-prepared films with good optical properties and high laser damage resistance. SAXS studies also offer the possibility to a good knowledge of the microstructure of the sols. In our hybrid system, the unhydrolyzed DEA ligands, which become anchored in the inorganic network, may considerably weaken the effects of PVP on the formation and growth of ZrO2 particles. Hence, the incorporation of a proper amount of PVP gives rise to negligible change of the sol structure and only a slight variation in refractive index and laser damage resistance of the films. However, at the slight expense of the refractive index and laser damage resistance, the incorporation of PVP can easily alleviate the stress incompatibility between different layers and facilitate the fabrication of the multilayer coatings. As the mass fraction of PVP reaches 15%—20%, a perfect match between different layers can be achieved, which ensures the successful deposition of 21-layer, nearly full-reflection coatings with the minimum transmittance of about 1.6%—2.1% (at 1064nm) and high laser damage threshold of 16.4—18.2J/cm2 (at 1064nm, 1ns pulse duration and R/1 mode).
The sinking depth of a projectile in granular media under gravity
Authors: Zhang Quan-Yi  , Wu Yao-Yu  , Peng Zheng  , Liu Rui  , Lu Kun-Quan  , Hou Mei-Ying  ,   (1)中国科学院物理研究所北京凝聚态物理国家实验室，北京  100080; (2)中国科学院物理研究所北京凝聚态物理国家实验室，北京  100080;铜仁学院物理系，铜仁  554300
Published: December 2020

The process of impact and penetration of a projectile with velocity u0 in a fine, loose granular system under acceleration due to gravity has been recorded experimentally by using fast video photography. The measured penetration depth as a function of the projectile mass agrees with the prediction of our previous drag force model in that at low impact velocity the penetration depth is linearly proportional to the mass of the projectile.
Thomson scattering with few-cycle laser pulses
Authors: Zhang Peng  , Song Yan-Rong  , Zhang Zhi-Gang  ,   (1)北京工业大学应用数理学院，北京  100022; (2)北京工业大学应用数理学院，北京  100022;北京大学信息科学与技术学院，北京  100871
Published: December 2020

In this paper, we analyze the relativistic Thomson scattering with few-cycle laser pulses. We conclude that scattering of high energy electrons with mono-cycle laser pulses is capable of producing attosecond pulses. The calculation shows that with a 1.5 cycle pulse at the wavelength of 1 μm, the normalized electric field intensity of 0.01,and the electron relativistic factor of 50, X-ray pulses of 0.2 as can be obtained. We also discussed the influence of the carrier-envelop phase offset and the initial phase φin of electrons starting to interact with the optical field on the radiation spectrum. The calculation results demonstrate that proper values of phase can result in single attosecond pulse generation, as well as the possibility of frequency tuning.
The method for constructing the exact solutions to the nonlinear evolution equation
Authors: Taogetusang  , Sirendaoerji  ,   内蒙古师范大学数学科学学院, 呼和浩特  010022
Published: December 2020

Based on tanh-function method, homogeneous balance method and auxiliary equation, a new auxiliary equation was introduced in the paper, meanwhile, a new invariance solution was obtained, and a new exact solitary wave solution for Benjamin-Bona-Mahoney(BBM) equation and modified BBM equation was constructed using the symbolic calculation system of Mathematica. The method introduced in the paper has general significance in searching for exact solutions to the nonlinear developing equation.
Bound state solutions of the Dirac equation with the Makarov potentials
Authors: Zhang Min-Cang  , Wang Zhen-Bang  ,   陕西师范大学物理学与信息技术学院, 西安  710062
Published: December 2020

The bound state solutions of the Dirac equation with equal scalar and vector Makarov potentials are obtained. It is shown that angular component of the Dirac equation can be solved with the gactorization method， which enables us to find immediately the eigenvalues and at the same time the manipulation process for the normalized eigenfunctions. The radial bound state solutions are expressed in terms of the confluent hypergeometric functions and the energy equation is derived from the boundary condition satisfied by the radial wavefunctions.
Generalized master equation for the nonextensive reaction-diffusion systems
Authors: Wu Jun-Lin  , Huang Xin-Min  ,   (1)陕西理工学院物理系，汉中  723000; (2)陕西师范大学物理学与信息技术学院,西安  710062
Published: December 2020

Based on the theory of nonequilibrium statistics and density operator equation, the generalized master equation satisfied by characteristic function for the nonextensive reaction-diffusion systems affected by pressure is derived by calculating the time variation of probability distribution function, where the pressure of the nonextensive systems is given in the framework of Tsallis statistics. This new equation not only depends on the nonextensive parameter but also has more nonlinear terms as compared with the master equation in the phenomenological theory, and is thus more general.
Cryptanalysis of multiple chaotic systems based public key encryption technique
Authors: Wang Kai  , Pei Wen-Jiang  , Zou Liu-Hua  , He Zhen-Ya  ,   东南大学无线电工程系，南京  210096
Published: December 2020

A novel public key encryption technique based on multiple chaotic systems has been proposed. This scheme employs m-chaotic systems and a set of linear functions for key exchange over an insecure channel. The security of the proposed algorithm grows as (NP)m, where N, P are the size of the key and the computational complexity of the linear functions, respectively. In this paper, the fundamental weakness of the cryptosystem is pointed out and a successful attack is described. Given the fact that any complex linear transformations on a vector will make the norm of the vector approximate linear growth, we present an attack that permits recovering the corresponding secret key from the public key and the initial value. Both theoretical and experimental results show that the attacker can access the secret key without any difficulty. The lack of security discourages the use of such algorithm for practical applications.
Chaos synchronization of the new hyperchaotic Chen system via nonlinear control
Authors: Wu Xiang-Jun  , Wang Xing-Yuan  ,   (1)大连理工大学电子与信息工程学院，大连  116024; (2)河南大学计算中心，开封  475001
Published: December 2020

This paper studies chaos synchronization of the new hyperchaotic Chen system via nonlinear control. A new method for improving the Lyapunov function of error dynamics of synchronization designed by Jiang and Huang et al is presented. The method removes the limitation occasioned by the Lyapunov function having only one form. Based on Lyapunov theory, a nonlinear controller is designed to synchronize two identical systems and two different chaotic systems. Chaos synchronization of two identical hyperchaotic Chen systems and two different chaotic systems (the hyperchaotic Chen system and the hyperchaotic R?ssler system) have been proved theoretically. Numerical simulations show the effectiveness of the proposed method.
A study of the surface enhanced Raman bond polarizability derivatives of ethylene thiourea：electromagnetic and charge transfer mechanisms
Authors: Liu Zhao-Jun  , Wu Guo-Zhen  ,   清华大学物理系，原子分子纳米科学教育部重点实验室，北京  100084
Published: December 2020

The surface enhanced Raman spectra of ethylene thiourea adsorbed on the silver electrode were measured at different electrode potentials. Based on the analysis of the Raman spectra, especially the bond polarizability derivatives elucidated from the Raman intensities by our algorithm, important information on the surface enhancement mechanisms was collected. The results show that both the electromagnetic and charge transfer mechanisms are responsible for the large enhancement, the former operating in the whole potential range between -0.3 and -1.2 V while the latter only in the range lower than -0.7 V.
Generation of controllable double-well optical trap for cold atoms (molecules) and its experimental studies
Authors: Mu Ren-Wang  , Li Ya-Li  , Ji Xian-Ming  , Yin Jian-Ping  ,   (1)华东师范大学物理系,光谱学与波谱学教育部重点实验室,上海  200062; (2)南通大学理学院,南通  226007; (3)南通大学理学院,南通  226007;华东师范大学物理系,光谱学与波谱学教育部重点实验室,上海  200062
Published: December 2020

In this paper, an experimental scheme of a controllable double-well optical trap for cold atoms (molecules) is briefly introduced, and the fabrication method of a binary π-phase plate and the experimental results to generate a controllable double-well optical trap are reported. In the experiment, we investigated the dependence of the double-well parameters (such as the spatial position of optical double-well, the spacing between the centers of two wells and the relative intensity distributions and so on) on the phase errors of the π-phase plate, and the change of double-well intensities resulting from errors in the engraving depth of the binary π-phase plate as well as the evolution of the optical trap from two wells to single one are studied both theoretically and experimentally. Experimental results consistent with theoretical prediction are obtained.
A laser diode system for 40K-87Rb atomic cooling
Authors: Wei Dong  , Chen Hai-Xia  , Xiong De-Zhi  , Zhang Jing  ,   山西大学光电研究所，量子光学与光量子器件国家重点实验室，太原  030006
Published: December 2020

We have developed a semiconductor laser system used in 40K-87Rb trapping and cooling experiment. The laser diode system is composed of three external cavity diode lasers and four injection diode lasers and a tapered amplifier. Four laser beams used for 40K and 87Rb cooling and repump lights are obtained by using acoustic optic modulators to offset the frequencies from the three external cavity diode lasers. Four light beams with different frequencies are injected into four slave lasers for injection locking. Then Rb cooling light, K cooling light and K repump light are injected into a semiconductor tapered amplifier in a master oscillator-power configuration. This configuration is flexible and stable and can simultaneously produce the cooling and repump light for 40K and 87Rb trapping and cooling experiment.
Numerical simulation of a novel rectangular-lattice single-polarization single-mode photonic crystal fiber
Authors: Zhang Fang-Di  , Liu Xiao-Yi  , Zhang Min  , Ye Pei-Da  ,   北京邮电大学电信工程学院，光通信与光波技术教育部重点实验室，北京  100876
Published: December 2020

A novel structure of single-polarization single-mode (SPSM) photonic crystal fiber (PCF) is proposed and analyzed numerically based on a full-vector finite element method with anisotropic perfectly matched layers. Through optimization a fiber with confinement loss less than 0.1 dB/km in the wavelengths range of 1.38 to 1.61 μm is obtained. The corresponding design procedures for the novel SPSM-PCF are also presented.
Study on the mechanism and measurement of stress of TiO2 and SiO2 thin-films
Authors: Gu Pei-Fu  , Zheng Zhen-Rong  , Zhao Yong-Jiang  , Liu Xu  ,   浙江大学现代光学仪器国家重点实验室，杭州  310027
Published: December 2020

The stress of TiO2 and SiO2 thin films has been researched, including stress model, measurement method and experimental results for different preparation conditions. Based on the model of curvature of deformed substrate, the stress of the films deposited with and without ion assist as well as with different substrate temperature has been measured and some useful results for both single layers and multilayer system of TiO2 and SiO2 have been obtained. The effect of packing density of the layer on stress is found as follows: the film with lower packing density shows a tensile and that with high pacing density shows a compress stress. The accumulated stress in multilayer system even can be diminished to zero by adjusting the preparation parameters.
Transmission properties of one-dimensional qusi-periodical phononic crystal
Authors: Cao Yong-Jun  , Dong Chun-Hong  , Zhou Pei-Qin  ,   内蒙古师范大学物理与电子信息学院，呼和浩特  010022
Published: December 2020

In this paper, the model of a one-dimensional (1D) phononic crystal with quasi-periodical structure is proposed. The transmission coefficients of elastic waves through the 1D qusi-periodical phononic crystal are numerically calculated, and the obtained transmission coefficients are compared with those of the phononic crystal with periodical structure. The results show that the band gap can also be found in the phononic crystal with quasi-periodical structure, and the frequency range of the gap is the same as that of the periodical structure. However, the only difference is that strongly localized resonant modes appear in the gap of the qusi-periodical phononic crystal. This study to the properties of the localized modes is useful to the fabrication of the acoustic or elastic wave filters.
Investigation of bubble dynamics in ultrasonic sonoporation
Authors: Chen Qian  , Zou Xin-Ye  , Cheng Jian-Chun  ,   南京大学声学研究所，南京  210093
Published: December 2020

During the process of quickly producing pathologic sections of the living tissues with ultrasonic sonoporation, it has been found that the exciting ultrasonic signal has an evident effect on the pathologic section. For the sake of understanding the effect and obtaining the best state of quickly producing pathologic section, the bubble dynamics in ultrasonic sonoporation is investigated by constructing a model of cavitated bubbles and altering the parameters, such as the ultrasonic signal frequency, acoustic pressure, bubbles' original radius and viscosity of the fluid. Numerical simulations indicate that radial vibration of cavitating bubble can keep on a steady process of expanding, shrinking, and vibrating in a given rang of frequencies, and one can find out the best original radius for obtaining the maximal cavitation. There exist a best cavitation regions which are determined by the parameters, i.e., the ultrasonic signal frequency, acoustic pressure, bubbles' original radius and viscosity of body fluid.
Numerical simulation of the internal flow in microwave plasma thruster in magnetic field
Authors: Yang Juan  , Su Wei-Yi  , Mao Gen-Wang  , Xia Guang-Qing  ,   西北工业大学航天学院，西安  710072
Published: December 2020

Recent experiments show that the performance of microwave plasma thruster is a little too low because the energy absorbed by plasma depends on the relationship of plasma and microwave frequency. One potential solution is to use external magnetic field to improve the transfer process of microwave in plasma. This paper presents numerical study about how a magnetic field affects the thermal plasma flow field and its temperature in microwave plasma thruster. Out purpose is to see if the magnetic field can enhance the thermal plasma core temperature. Assuming that the plasma within the thruster is under the condition of local thermal equilibrium and the external magnetic fields is uniform, coupled Navier-Stokes, Maxwell and Saha equations are set up to describe the plasma flow under microwave electromagnetic and external magnetic fields. Solving Navier-Stokes equations with semi-implicit method for pressure-linked equations and Maxwell equations with finite-difference time-domain method, the result shows that when the magnetic field intensity is 0.5 T the temperature of plasma core is increased by 24% compared with that at zero magnetic field. Thus the magnetic field improves the performance of microwave plasma thruster.
The structure and X-ray photoelectron spectroscopy analysis of double-atom filled skutterudite compounds
Authors: Li Han  , Tang Xin-Feng  , Zhao Wen-Yu  , Zhang Qing-Jie  ,   武汉理工大学材料复合新技术国家重点实验室，武汉  430070
Published: December 2020

Double-atom filled single-phase CamCenFexCo4-xSb12 compounds were synthesized through a melting—quenching—diffusion—annealing procedure. Ca and Ce were used as filling atoms. The structure of double-atom filled skutterudite compounds was investigated via Rietveld refinement and X-ray photoelectron spectroscopy analysis. The results of Rietveld refinement indicate that CamCenFexCo4-xSb12 compounds have skutterudite structure, and the Sb-icosahedron voids were filled with Ca or Ce. The thermal parameter (B) of Ca/Ce is much larger than those of Sb and Fe/Co in the compounds. The specific chemical states of atoms were obtained from X-ray photoelectron spectroscopy quantitative analysis, the results show that the Sb atoms have five chemical states, and the relative percentages of Sb atoms in different chemical states are correlative with the total filling fraction. The filling atoms tend to be located at the center of the voids of the Sb-icosahedrons preferentially.
Molds for nanoimprinting made by modified photoresist
Authors: Chen Lei-Ming  , Guo Yan-Feng  , Guo Xi  , Tang Wei-Hua  ,   (1)中国科学院物理研究所北京凝聚态物理国家实验室，北京  100080; (2)中国科学院物理研究所北京凝聚态物理国家实验室，北京  100080;浙江理工大学物理系，杭州  310018; (3)中国科学院物理研究所北京凝聚态物理国家实验室，北京  100080;郑州航空工业管理学院数理系，郑州  450015
Published: December 2020

The molds for nanoimprint is very important for nanoimprinting. Many hard materials have been used to make molds. But these materials are difficult to fabricate. In this paper we present a novel technique for making molds based on the modification of polymer by focused ion beam irradiation. This technique is very fast and simple. It can be used in many other domainus of nanofabrication.
Structure, magnetic properties and atomic immigration of CoFe2O4 nanoparticles
Authors: Wang Li  , Wang Hai-Bo  , Wang Tao  , Li Fa-Shen  ,   兰州大学磁学与磁性材料教育部重点实验室，兰州  730000
Published: December 2020

CoFe2O4 nanoparticles have been prepared by sol-gel method. M?ssbauer spectra at temperature varying from 80 to 873 K showed that the atomic site preference of nanoparticles is different from that of the bulk material. The results also showed that the Tc of nanosized CoFe2O4 is much lower than that of the bulk counterpart. This decrease of Tc in the nanoparticles may be attributed to the redistribution of Fe and Co cations at the A and B sites. The M?ssbauer spectra also revealed that the hyperfine field varied with the temperature and the hyperfine interaction follows T3/2+T5/2 law approximately. The average isomer shift decreases almost linearly with increasing temperature.
Thermodynamic characteristics of metallic glass-forming liquids
Authors: Xia Ming-Xu  , Meng Qing-Ge  , Zhang Shu-Guang  , Ma Chao-Li  , Li Jian-Guo  ,   (1)北京航空航天大学材料科学与工程学院，北京  100083; (2)上海交通大学材料科学与工程学院，上海  200030
Published: December 2020

On the basis of analyzing the thermodynamic model of regular melt, the mixing enthalpy ΔHmix and the mixing entropy ΔSmix of typical metallic glass melts were calculated. The distribution of ΔHmix vs. ΔSmix for typical metallic glasses was generalized, and a strategy for pinpointing metallic glass formers has been proposed by combining the critical cooling rate Rc based on the atomic intrinsic characteristics of the alloys including atom size, composition, and mixing enthalpy of binary systems among the components. On the condition of ΔSmix greater than 0.6 J·K-1mol-1 and ΔH less than -15 kJ·mol-1, the alloy tends to form a bulk metallic glass(BMG). It shows that Rc is intimately related with ΔSmix, and can be expressed as Rc=42.24×104 exp(-13.91 ΔSmix)+19.66. Two new glass formers, Zr40Al10Ni15Cu35, located far from the glass forming area of the existing Zr-Al-Ni-Cu BMGs with a content of 55at%—65at% zirconium, and Fe53Co5Nd12B30 of quaternary Fe-B-based BMG, were successfully prepared with this approach.
Diffusion and interface reaction of Cu and Si in Cu/SiO2/Si (111) systems
Authors: Cao Bo  , Bao Liang-Man  , Li Gong-Ping  , He Shan-Hu  ,   兰州大学物理科学与技术学院，兰州  730000
Published: December 2020

The Cu thin films were deposited on p-type Si (111) substrates by magnetron sputtering at room temperature. The diffusion and interface reaction of Cu/SiO2/Si (111) systems were studied for different annealing temperatures by X-ray diffraction (XRD) and Rutherford backscattering (RBS).We obtained some useful results in the following aspects：The onset temperature of interdiffusion was 450℃ for the Cu/SiO2/Si (111) systems.With the increase of annealing temperature, the interdiffusion was more apparent. There were no copper silicides formed below annealing temperature of 450℃ for the Cu/SiO2/Si (111) systems. The onset temperature of silicification was 500℃. Copper silicides were formed on the samples after annealing at 500℃.
Heat conduction in one-dimensional systems with damping
Authors: Li Xin-Xia  , Tang Yi  ,   湘潭大学现代物理研究所，湘潭  411105
Published: December 2020

By making use of the method of molecular dynamics, we study the behaviors of heat conduction in one-dimensional systems under the influence of damping. The results show that when the integrability of the systems is destroyed by the damping, linear temperature profiles appear even in the harmonic lattices. Weak damping acts as a sort of perturbation in nonintegable systems and does not substantially change their temperature profiles and the thermal conductivity, while it causes essential change in integrable systems. However, in the case of strong damping, because of the excessive dissipation of energy, temperature profiles in a sunken shape and the convergent thermal conductivity appear.
Effects of nonlinearity on the transmission property of superlattices
Authors: Liu Bing-Can  , Pan Xue-Qin  , Ren Zhi-Ming  ,   装甲兵工程学院基础部，北京  100072
Published: December 2020

We investigate the effects of nonlinearity on the transmission property of superlattices. The nonlinear Schr?dinger equation leads to a second order nonlinear difference equation, and we obtain transmission spectrum of wave by iterating the difference equation. The transmission spectrum shows that the nonlinear coefficient has a distinctive modulation effect on the transmission coefficient.
Research of two-dimensional hole gas in p-GaN/Al0.35Ga0.65N/GaN strained quantum-well
Authors: You Da  , Xu Jin-Tong  , Tang Ying-Wen  , He Zheng  , Xu Yun-Hua  , Gong Hai-Mei  ,   中国科学院上海技术物理研究所传感技术国家重点实验室，上海  200083
Published: December 2020

In this paper, the two-dimensional hole gas (2DHG) induced in the heterojunction were investigated in detail. The density of the 2DHG was calculated at first, then, based on the semiconductor-insulator-semiconductor and superlattice critical thickness model and using the self consistent Poisson-Schrdinger calculations, the influence of the AlGaN barrier and the top GaN layer thickness on the distribution of the 2DHG were calculated when the barrier layer is fully strained and half strained. The Schottky device with this structure was fabricated and C-V measurement was made to verify the existence of the 2DHG and the validity of calculation results. Finally, the 2DHG effects on p-GaN/AlGaN/GaN Schottky photodetector were investigated. Due to the polarization and Stark effect, the spectral responses with the 10nm blue shift are observed. Under zero bias, the peak responsivity of the device is about 0.022A/W, and increases to 0.19A/W under 1V reverse bias, which approaches the theoretical limit.
Transport properties and photo-induced effect in La0.82Te0.18MnO3 thin film
Authors: Wang Jian-Yuan  , Chen Chang-Le  , Gao Guo-Mian  , Han Li-An  , Jin Ke-Xin  ,   (1)西北工业大学理学院，西安  710072; (2)西北工业大学理学院，西安  710072;空军工程大学理学院，西安  710051
Published: December 2020

The transition from the metallic phase to the nonconductive phase occurred at 283 K in La0.82Te0.18MnO3 thin film prepared by pulse laser deposition method. The transport results show that the data satisfy the formula of electro-electro and electro-magnon scattering for TTMI; when T>TMI it agrees with small polaron transport model. The effect of the continuous wave laser(532 nm，40 mW) on the film was also investigated. Below TMI, the resistivity has a photo-induced increase. The maximum rate of resistivity changes(Δρ/ρ0) can reach 51.1%， which is much greater than that of hole-doped manganites. Above TMI there is a photoconduction. The relaxation was observed in the experiment when the laser was turned on and off. The resistively is exponentially related with the time.
Synthesis and thermoelectric properties of Sb-doped type-Ⅰ Ge clathrates Ba8Ga16-xSbxGe30
Authors: Xiong Cong  , Tang Xin-Feng  , Qi Qiong  , Deng Shu-Kang  , Zhang Qing-Jie  ,   武汉理工大学材料复合新技术国家重点实验室，武汉  430070
Published: December 2020

The single-phase Sb-doped n-type Ba8Ga16-xSbxGe30 compounds were synthesized by melting reaction combined with spark plasma sintering. Influences of substituting Sb for Ga on the thermoelectric properties of the compounds were investigated. The results indicate that with the increase of Sb substitution fraction the Seebeck coefficient is decreased gradually, and the temperature which corresponds to the peak value of Seebeck coefficient moves to low-temperature. The electrical conductivity of the compounds increases at first and then decreases with the increase of x; when x=2, it reaches maximum. Substituting Sb for Ga has a great influence on the thermal properties of the compounds. Both the thermal conductivity and lattice thermal conductivity decrease in various degrees. Of all n-type Ba8Ga16-xSbxGe30 compounds, the compound Ba8Ga14Sb2Ge30 has the greatest ZT value, the maximal value of which reaches 1.1 at about 950 K.
The formation and thermal stability of exchange bias in NiFe/PtMn bilayers
Authors: Li Yan  , Chen Qing-Yong  , Jiang Hong-Wei  , Wang Ai-Ling  , Zheng Wu  ,   首都师范大学物理系，北京  100037
Published: December 2020

(Ni0.81Fe0.19)1-xCrx/NiFe/PtMn films were prepared by magnetron sputtering. The formation and thermal stablitity of NiFe/PtMn bilayers were systematically investigated. The experiment shows that the grain size of PtMn layer depends strongly on the change in Cr concent ration. Thermal stability of exchange bias indicates that (Ni0.81Fe0.19)1-xCrx/NiFe/PtMn films with larger PtMn grains have a higher blocking temperature, and the bigger grain size is helpful in reducing the critical thickness of PtMn layer, which is consistent with Mauri's model.
The effect of a Bi underlayer on FePt thin film
Authors: Feng Chun  , Li Bao-He  , Han Gang  , Teng Jiao  , Jiang Yong  , Liu Quan-Lin  , Yu Guang-Hua  ,   (1)北京科技大学材料物理与化学系，北京  100083; (2)北京科技大学材料物理与化学系，北京  100083;北京工商大学数理部，北京  100037
Published: December 2020

In this paper, the FePt films with Bi underlayer were prepared by dc magnetron sputtering on glass substrates. The L10-FePt films were obtained after the deposited samples were subjected to vacuum annealing at various temperatures. The effect of a Bi underlayer on the ordering temperature and magnetic properties of FePt films was studied. Experimental results show that the FePt film can realize the low-temperature ordering at 350℃ after introduction of a Bi underlayer. Moreover, the Bi underlayer can also obviously enhance the coercivity Hc of the film and enlarge the concentration range of FePt films with high Hc. We studied the distribution of Bi atoms by X-ray photoelectron spectroscopy and the change of crystal structure of FePt films by X-ray diffraction. The cause of the above observatious is associated with enhanced ordering degree of FePt films by the Bi diffusion during annealing process.
Microstructures and electrical properties of CaCu3Ti4O12 ceramics
Authors: Shao Shou-Fu  , Zheng Peng  , Zhang Jia-Liang  , Niu Xiao-Kun  , Wang Chun-Lei  , Zhong Wei-Lie  ,   山东大学物理系，济南  250100
Published: December 2020

CaCu3Ti4O12 ceramics are prepared by the conventional solid-state reaction method with various sintering temperatures. Microstructures are examined by scanning electronic microscopy, and it is found that they could be categorized into three different types. Dielectric properties and complex impedances are investigated in the frequency range of 40 Hz—110 MHz over a temperature range of 25—280℃. The room temperature dielectric constant increases with sintering temperature. With increasing the measuring temperature, ceramics with different microstructures show diverse electrical properties. However, some common features exist among the electrical properties. For all of the ceramics, dielectric dispersion shows a low-frequency response and two Debye-type relaxations, and there exist three semicircles in the complex impedance plane at high temperatures. The observed electrical properties are ascribed to the detailed internal polycrystalline microstructure, i.e., to come from the contributions of the domains, the grain boundaries and defects inside grains such as domain boundaries, etc.
The critical phenomena of the dilute-to-dense transition in two-dimensional granular flow
Authors: Zhong Jie  , Peng Zheng  , Wu Yao-Yu  , Shi Qing-Fan  , Lu Kun-Quan  , Hou Mei-Ying  ,   (1)北京理工大学应用物理系,北京  100081; (2)中国科学院物理研究所北京凝聚态物理国家实验室,北京  100080; (3)中国科学院物理研究所北京凝聚态物理国家实验室,北京  100080;北京理工大学应用物理系,北京  100081
Published: December 2020

The criticality of the dilute-to-dense transition in an inclined two-dimensional(2D) granular channel flow is investigated. The waiting time t before the transition occurs and after the flow is initiated is recorded. It is found that the probability function C(t) for the flow remaining dilute at time t decays exponentially with a characteristic time α-1(d). The characteristic time is found to be fitted well by a power law a(dc-d)-γ, where dc is the critical opening size: as for d>dc, the transition will never happen. The existence of a critical opening size at the exit confirms that the dilute-to-dense transition in 2D granular flow is a critical transition.
Investigation of improved conversion efficiency of microcrystalline silicon thin film solar cells
Authors: Zhang Xiao-Dan  , Zhao Ying  , Gao Yan-Tao  , Chen Fei  , Zhu Feng  , Wei Chang-Chun  , Sun Jian  , Geng Xin-Hua  , Xiong Shao-Zhen  ,   南开大学光电子薄膜器件与技术研究所，天津  300071;南开大学光电子薄膜器件与技术天津市重点实验室，天津  300071
Published: December 2020

A series of microcrystalline silicon thin films solar cells were fabricated by very high frequency plasma enhanced chemical vapor deposition at different total gas flow rates and on different back reflectors. The results of I-V measurements of solar cells showed that the characteristic parameters of solar cells were all improved with the increase of total flow rate, so conversion efficiency of solar cells were increased. In addition, short circuit current (Jsc) of solar cells was greatly reduced, as a result, conversion efficiency of solar cells were improved when ZnO/Ag/Al back reflector were incorporated into solar cells. The details can be seen in the paper.
Information processing of multidimensional simultaneity fluorescence with two-photon array excitation
Authors: Lin Zi-Yang  , Fu Zhe  , Liu Li-Xin  , Hu Tao  , Qu Jun-Le  , Guo Bao-Ping  , Niu Han-Ben  ,   深圳大学光电子学研究所,光电子器件与系统教育部重点实验室,广东省光电子器件与系统重点实验室,深圳  518060
Published: December 2020

Microscopical imaging method of five-dimensional simultaneity fluorescence information is a new technology for acquiring fluorescence information, which makes use of two-photon array excitation to acquire information of fluorescence position, fluorescence spectrum and fluorescence lifetime for each array element. It removes the limitation on existing fluorescence detection technology in which different functional informations are not obtained simultaneously. In this paper, the methods for deriving geometrical intensity image, different spectral intensity images and different spectral life-time images from the complex information of the new technology are presented. Because of array excitation, there is asymmetry in the array excitation intensity, which influences the excited fluorescence intensity. A method based on the excitation fluorescence intensity correction coefficient matrix is put forward, which eliminates effectively the influence of the asymmetry of array excitation intensity. Data collection and processing for actual samples are made and imaging results are got. The experimental results show the validity of the processing methods and some unsolved problems in the processing methods are discussed.
An explicit analytical solution of the Schr?dinger equation for a detuned quantum frequency conversion system
Authors: Li Jiang-Fan  , Shan Shu-Min  , Yang Jian-Kun  , Jiang Zong-Fu  ,   (1)长沙理工大学计算机与通信学院,长沙 410076; (2)长沙理工大学物理与电子科学学院,长沙 410076；国防科技大学理学院,长沙 410073; (3)国防科技大学理学院,长沙 410073
Published: December 2020

The time-dependent invariant of a quantum frequency conversion system in an optical cavity is found from the simple observation that the dynamical evolution of a sum-frequency generation process preserves the total number of the idler photons and the signal photons involved in the process. By using this invariant and the Lewis-Riesenfeld quantum invariant approach, the Schrdinger equation for the coupled system of the two quantized modes of the electromagnetic field is solved under detuned condition. The explicitly analytical formulae of the quantum states and the evolution operators of the system are obtained. It should be useful for further studies on the various quantum properties of the quantum system.
A family of asymptotically good quantum codes based on code concatenation
Authors: Li Zhuo  , Xing Li-Juan  ,   西安电子科技大学综合业务网国家重点实验室,西安 710071
Published: December 2020

Using the idea of code concatenation in classical coding theory, we make the suggestion of constructing general concatenated quantum codes by choosing certain quantum codes as outer code and inner code. Then by concatenating quantum RS outer codes with a set of special quantum inner codes, one can construct a family of concatenated quantum codes, which is asymptotically good. In the field of quantum error-correcting codes, this is the first time that a family of asymptotically good quantum code is constructed using bad classical codes.
Second interference and amplification effect of a Bose-condensed gas
Authors: Xu Zhi-Jun  , Li Peng-Hua  ,   浙江工业大学应用物理系，杭州 320032
Published: December 2020

For a Bose-condensed gas in a combined potential consisting of an axially-symmetric harmonic magnetic trap and one-dimensional (1D) optical lattices, the motional interference side peaks along the axis direction are formed after the combined potential is switched off. Based on this physical system, we make a new experimental suggestion which can be realized with current experimental technique to investigate the side peak superposition and discuss the second interference and amplification effect of a Bose condensate. In the region where the side peaks undergo constructive interference, the density of condensed atomic cloud will be amplified effectively.
Stochastic resonance in an asymmetric bistable system with time-delayed feedback and correlated noises
Authors: Dong Xiao-Juan  ,   西北工业大学理学院数学系，西安 710072
Published: December 2020

In this paper,the phenomenon of stochastic resonance in an asymmetric bistable system with time-delayed feedback and correlated noises is investigated . The explicit expression for signal-to-noise ratio is obtained under the condition of small time delay approximation and adiabatic approximation. The effects of the delay time,the noises correlation and the static asymmetry to the signal-to-noise ratio are discussed.
Stochastic resonance in an asymmetric bistable system driven by mixed periodic force and noises
Authors: Zhou Bing-Chang  , Xu Wei  ,   西北工业大学应用数学系,西安 710072
Published: December 2020

The phenomenon of stochastic resonance (SR) in an asymmetric bistable system driven by correlated multiplicative and additive noise and two periodic fields is investigated. Analytic expressions of the signal-to-noise ratio (SNR) for fundamental and higher harmonics are derived using the two-state theory. The SR appears in both fundamental and higher harmonics. Moreover, the suppression exists for higher harmonics. The effects of static asymmetry and the noise intensity and the strength of coupling between noises on the SNR are studied.
Impulsive control and synchronization of a new chaotic system
Authors: Luo Run-Zi  ,   南昌大学数学系,南昌 330031
Published: December 2020

In this paper we discuss the new chaotic system proposed by Huang Wei. We give the sufficient conditions for the stabilization and synchronization of this new chaotic system via impulsive control. For these sufficient conditions that B is not necessarily symmetric. Thus, our results can be used for a wider class of nonlinear systems. Simulation results are provided to show the effectiveness of the proposed method.
The second super-harmonic stochastic resonance in the neural networks with small-world character
Authors: Zhou Xiao-Rong  , Luo Xiao-Shu  , Jiang Pin-Qun  , Yuan Wu-Jie  ,   广西师范大学物理与电子工程学院,桂林 541004
Published: December 2020

Stochastic resonance is a common natural phenomenon in nonlinear systems. By studying the relations between the out put signal-to-noise ratio (SNR) of the biologic neural network with small-world character and the rewiring probability p which reflects the effect of small-world,the coupling strength c, amplitude A of input signal, we revealed some regularities of the second super-harmonic stochastic resonance in the biologic neural network, and found that the out put SNR doesn't monotonicly increase as the forcing amplitude A increases, but there exists an optimal value AO for the Hodgkin-Huxley (HH) neural network with small-world character. The out put SNR reaches its maximum when A is equal to AO.
Femtosecond frequency comb and optical frequency measurement of 532 nm Nd:YAG laser
Authors: Fang Zhan-Jun  , Wang Qiang  , Wang Min-Ming  , Meng Fei  , Lin Bai-Ke  , Li Tian-Chu  ,   中国计量科学研究院,北京 100013
Published: December 2020

In this paper we report on the Ti:sapphire mode-locked femtosecond laser based optical frequency comb apparatus and developed by NIM its application in optical frequency measurement of the I2 stabilized 532nm Nd∶YAG laser installed in NIM. The measurement result of 127I2 R(56)32-10 hyperfine transition is 563260223512991±20　(Hz), with a relative frequency uncertainty of 3.6×10-14. To our knowledge，this result is the first optical frequency measurement in China which is referenced directly to the Cs microwave frequency standard.