bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent progress in research on solid organic-inorganic hybrid solar cells
Authors: Yuan Huai-Liang  , Li Jun-Peng  , Wang Ming-Kui  ,   Wuhan National Laboratory for Optoelectronics, HuaZhong University of Science and Technology, Wuhan 430074, China;,   Kunming Institute of Precious Metals, Kunming 650106, China
Published: December 2020

Recently solid-state organic-inorganic hybrid solar cells based on perovskite structured materials have evidenced a great breakthrough due to their perfect light absorption and charge transfer optoelectronic properties. The power conversion efficiencies have exceeded 20.1% during the last 5 years, since the first report on perovskite solar cells with an efficiency of 3.8% in 2009. Remarkably, perovskite solar cells with a planar-heterojunction structure have achieved an efficiency of 19.3%, and the perovskite solar cells with conventional mesoporous structure have achieved a certified efficiency above 16.7%. This review article first introduces the development of the third generation of solar cells from dye-sensitized solar cells to the perovskite solar cells, and then focuses on the optical and physical properties of the perovskite materials and their application in solid-state solar cells. We discuss the performance characteristics and advantages of the perovskite solar cells having mesoporous, planar heterojunction, flexibility, and hole-conductor-free structure respectively, and the charge collection layer which is applied in perovskite solar cells, such as semiconductor oxide (TiO2, Al2O3, ZnO and NiO) and PEDOT:PSS, etc. More over this review article introduces the charge transport materials, including P3HT, spiro-OMeTAD, PTAA, and PCBM, as well as different photoabsorption material, such as CH3NH3PbI3, CH3NH3PbBr3 and CH3NH3PbI3-xClx, etc. aiming to analyze their performance characteristic in the perovskite solar cells with different configurations; and the main factor related to the performance. Finally, this review elaborates the perspective and understanding of the perovskite solar cells and points out the critical point and expectation for improving the performance of perovskite solar cells further.
Hole scattering and mobility in compressively strained Ge/(001)Si1-xGex
Authors: Bai Min  , Xuan Rong-Xi  , Song Jian-Jun  , Zhang He-Ming  , Hu Hui-Yong  , Shu Bin  ,   Key Lab of Wide Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

Strained Ge attracts attention of researchers for its high mobility and compatibility with Si technology. Based on the valence band model for compressively strained Ge/(001)Si1-xGex, the relationships between hole scattering, mobility, and Ge content (x) are established in this paper, including ionized impurity, acoustic phonon, non-polar optical phonon, total scattering rates, and the averaged and directional mobility of holes. Our quantitative data gained within the models can provide valuable references for the research of modified Ge materials physics and the design of the related devices.
progress in electron-transport materials in application of perovskite solar cells
Authors: Ting Hung-Kit  , Ni Lu  , Ma Sheng-Bo  , Ma Ying-Zhuang  , Xiao Li-Xin  , Chen Zhi-Jian  ,   Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, China;,   Advanced high school of Yantai Economic development zone, Yantai 264006, China
Published: December 2020

Ever since the first organic-inorganic hybrid halogen perovskite solar cell was first used as a photo-voltaic material in 2009, reports on this type of solar cell have grown exponentially over the years. Up till May 2014, the photo-energy conversion efficiency of the perovskite solar cell have already achieved an efficiency approaching 20%. Surpassing the efficiency achieved by organic and dye synthesized solar cell, the perovskite solar cell is in good hope of reaching the efficiency compatible with that of mono-crystalline silicon solar cell, thus it is going to be the star in photo-voltaic industry. In a perovskite solar cell, the film-formation and electron-mobility in the electron transfer layer can dramatically affect its efficiency and life-span. Especially in the up-right structured device, the mesoscopic structures of the electron-transfer layer will directly influence the growth of the perovskite layer. The present researches of electron transport materials mainly focus on three aspects: (1) How to improve the instability in mesoporous TiO2-mesosuperstructured solar cells, that arises from light-induced desorption of surface-adsorbed oxygen. (2) How to obtain TiO2 or other electron transport materials at low temperature (sub 150 ℃) in order to be applicatable in flexible devices. (3) How to substitute the mesoporous TiO2 or compact TiO2 transport layer by organic or composite materials. This article devides the materials that are used to make the electron-transfer layer into three distinct groups according to their chemical composition: i.e. metal oxides, organic small molecules, and composite materials, and introduces about the role they play and the recent development of them in constructing the perovskite solar cell.
Factors influencing the stability of perovskite solar cells
Authors: Zhang Dan-Fei  , Zheng Ling-Ling  , Ma Ying-Zhuang  , Wang Shu-Feng  , Bian Zu-Qiang  , Huang Chun-Hui  , Gong Qi-Huang  , Xiao Li-Xin  ,   School of Physics, Peking University, Beijing 100871, China;,   College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
Published: December 2020

In 2009, organic-inorganic hybrid perovskite was first used as the light-absorbing material for solar cells. The rapidly increased efficiency, simple preparation process, and low cost have aroused widespread concern. The last five years have witnessed the increase of the power conversion efficiency in the organic-inorganic hybrid perovskite solar cells from 3.8% to 19.3%. At present, most researches focus on how to improve the photoelectric conversion efficiency rather than the stability. With the improvement of the power conversion efficiency, people have realized that the long-term stability is also one of the key issues in practical applications.The present preliminary researches indicate that there are two main factors connected with the stability. One is the stability of the perovskite materials, including thermal stability and humidity stability; the other is the stability of solar devices, mainly related to the design and optimization of devices' structure. To solve the problems of stability of perovskite materials, the main point is its crystal structure. Based on the tolerance factor related to the stability of the perovskite lattice structure, choosing a more suitable size of the moiety can reduce its sensitivity to humidity and improve its stability. To design the device structure, we should try to select a hydrophobic material to protect the perovskite materials from being affected by the surrounding environment. Researches have so far showed that by optimizing the design of the solar cell structure via combining the elements utilized and the bonding interface work, the stability of the hybrid perovskites solar cell is supposed to be entirely solved, and this will determine the practical process of hybrid perovskite photovoltaic materials. However, by the moment, the study on stability of perovskite solar cells is far from being sufficient.
Characterizations of clusters generated by pure xenon and hydrogen xenon gas mixture at room temperature
Authors: Zhao Jia-Rui  , Li Yi-Fei  , Ma Jing-Long  , Wang Jin-Guang  , Huang Kai  , Han Yu-Jing  , Ma Yong  , Yan Wen-Chao  , Li Da-Zhang  , Yuan Da-Wei  , Li Yu-Tong  , Zhang Jie  , Chen Li-Ming  ,   Laboratory of Optical Physics, Beijing National Laboratory for Condensed Matter Physcis, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   Key Laboratory for Laser Plasmas of Ministry of Education, Shanghai Jiaotong University, Shanghai 200240, China;,   Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Rayleigh scattering method can be used to investigate the cluster size and the cluster formation process, and its advantages are that it is easy to perform and non-disruptive. In this paper, by measuring the Rayleigh scattering intensities of clusters generated respectively in pure xenon gas and hydrogen-xenon gas mixture, the relationships of Rayleigh scattering intensity to time, backing pressure, and mixture ratio are studied, and according to these relationships, the average sizes of clusters under different conditions are estimated. Through the scaling law of the Rayleigh scattering intensity obtained in hydrogen-xenon gas mixture with respect to upstream gas pressure, i.e., I= (1.5 10-5)P6.47, the hydrogen of mixed gas is found to be conducible to the generating of xenon clusters. The advantages of hydrogen-xenon gas mixture for generating clusters are analyzed theoretically from the perspective of thermodynamics and intermolecular forces, and a new phenomenon, i.e., the hydrogen xenon gas mixture is not easy to liquefy, is found. This finding provides a new way to generate larger size clusters. Our results are expected to provide guidelines for the future experimental researches of the X-ray generated by xenon clusters and of the neutron generated by the deuterium-xenon mixture gas.
Elastic collisions between excited-state Li and ground-state Ar atoms at low temperature and analytic potentic energy function and molecular constants of the LiAr (A2Π) radical
Authors: Han Ya-Nan  , Jiang Gang  , Fan Quan-Ping  , Gao Yu-Feng  , Du Ji-Guang  ,   Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China;,   Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610065, China
Published: December 2020

The potential energy curve (PEC) for the first excited state (A2Π) of LiAr is calculated using the multireference configuration interaction method in combination with the basis set, ang-cc-PCVQZ. The Davidson correlation (+Q) and the scalar relativistic effect (+DK) are taken into account in the calculations. And PEC is fitted to analytical Hartree-Fock-dispersion potential function, thereby determining the spectroscopic parameters. These obtained parameters are in excellent agreement with the available experimental and theoretical values. By solving the radial Schrödinger equation of nuclear motion, the vibration levels, rotary inertia and six centrifugal distortion constants (Dv, Hv, Lv, Mv, Nv, Ov) are obtained for the first time. The elastic collisions between the excited-state Li and the ground-state Ar atoms are investigated at low and ultralow temperatures when the two atoms approach to each other along the LiAr (A2Π ) interaction potential. The total and various partial-wave cross sections are calculated at energies from 1.0×10-12 to 1.0×10-3 eV by numerical calculation. The effect of each partial-wave cross section on the total elastic cross section is discussed carefully. The results show that the total elastic cross section is very large and almost constant at ultralow temperatures, and its shape is mainly dominated by the s-partial wave. But with the increase of collision energy, contribution of s-partial wave to the total cross section decreases and the contribution of higher-order partial wave to scattering cross section increases gradually.
Investigation of quantum discord for two-spin system
Authors: Wang Dan-Qin  , He Chuang-Chuang  ,   School of Advanced Materials and Nanotechnology, Xidian University, Xi'an 710126, China
Published: December 2020

By adopting the concept of the geometric measure of quantum discord, we explore the property of quantum correlation in the two-spin Heisenberg model, gain the analytic expression of quantum discord in the general case, and discuss the influences of the coupling constant, temperature, the intensity of the external magnetic field on magnitude of the quantum correlation. The corresponding scheme of tuning quantum correlation is also given in this paper. In addition, we find that quantum discord has a sudden transition in the lower temperature. Results show that adjusting systematic parameters, which are temperature, coupling strength, magnetic field intensity, etc, is an effective way to control the value of quantum correlation in the double spin Heisenberg model system. This provides a certain reference and significant guidance for the precise control of quantum discord and realizing the teleportation of quantum state and the design of quantum logic gates.
Image smoothing model based on the combination of the gradient and curvature
Authors: Zhou Xian-Chun  , Wang Mei-Ling  , Shi Lan-Fang  , Zhou Lin-Feng  , Wu Qin  ,   College of Electronic and Information Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   Jiangsu Key Laboratory of Meteorological Observation and Information Processing, Nanjing University of Information Science and Technology, Nanjing 210044, China;,   College of Mathematics and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044, China
Published: December 2020

In image processing, in order to keep the detailed information about image edge, we propose a curvature smoothing model based on the nature of diffusion coefficient and curvature. Considering the fact that the curvature will change significantly when the image is affected by noise pollution, in this article we will continue to take the level set curvature as a detection factor and substitute it into the model, then we present a new model which combines gradient and curvature. Analysis and simulation indicate that the new model can keep more image information than the Perona-Malik model, and it can strengthen the sharp edge of the image efficiently, and well keep the straight lines of image, and edges, corners, slopes and small-scale features of curve at the same time, so this model is an ideal model.
Self-excited oscillation mechanism of a standing-wave thermoacoustic system
Authors: Wang Tuo  , Wu Feng  , Li Duan-Yong  , Chen Hao  , Lin Jie  ,   School of Mechanical and Electrical Engineering, Wuhan Institute of Technology, Wuhan 430073, China;,   Architecture Design Institute, China Construction Third Engineering Bureau Group CO., LTD., Wuhan 430064, China
Published: December 2020

The onset process of a thermoacoustic prime mover is a process generating and maintaining self-excited oscillation. It is helpful to have a better understanding of thermoacoustic effect by investigating the mechanism of thermoacoustic self-excited oscillation. The network model of a representative standing-wave thermoacoustic prime mover is established on the basis of thermoacoustic network theory. Comparing thermoacoustic network to electric network, the apparent power flux which inputs the thermoacoustic network is calculated by using the Hermitian form. In the network, the apparent power flux balance means establishing the self-excited oscillation. Based on the above, the threshold temperature and operation frequency of a thermoacoustic prime mover are calculated on condition that the imaginary part of angular frequency is equal to zero. The calculation results are in good agreement with the experimental results. For the coupling relationship of the main pressure with the threshold temperature and operation frequency, the calculation results are roughly close to the experimental results. The obtained results are helpful for the further studying of the thermoacoustic effect and the optimal designing of a thermoacoustic system.
Dynamical model of Cosserat elastic rod based on Gauss principle
Authors: Liu Yan-Zhu  , Xue Yun  ,   Department of Engineering Mechanics, Shanghai Jiao Tong University, Shanghai 200240, China;,   School of Mechanical Engineering, Shanghai Institute of Technology, Shanghai 201418, China
Published: December 2020

Based on the generalized principles of dynamics, the feature of Gauss principle of least constraint is that the motion law can be directly obtained by using the variation method of seeking the minimal value of the constraint function without establishing any dynamic differential equations. According to the Kirchhoff's dynamic analogy, the configuration of an elastic rod can be described by the rotation of rigid cross section of the rod along the centerline. Since the local small change of the attitude of cross section can be accumulated infinitely along the arc-coordinate, the Kirchhoff's model is suited to describe the super-large deformation of elastic rod. Therefore the analytical mechanics of elastic rod with arc-coordinate s and time t as double arguments has been developed. The Cosserat model of elastic rod takes into consideration the factors neglected by the Kirchhoff model, such as the shear deformation of cross section, the tensile deformation of centerline, and distributed load, so it is more suitable to modeling a real elastic rod. In this paper, the model of the Cosserat rod is established based on the Gauss principle, and the constraint function of the rod is derived in the general form. The plane motion of the rod is discussed as a special case. As regards the special problem that different parts of the rod in space are unable to self-invade each other, a constraint condition is derived to restrict the possible configurations in variation calculation so as to avoid the invading possibility.
Simulation of X-ray spectrum of Ar tracer in indirectly driven implosion
Authors: Qiao Xiu-Mei  , Zheng Wu-Di  , Gao Yao-Ming  ,   Institute of Applied Physics and Computational Mathematics, Beijing 100094, China
Published: December 2020

As the X-ray spectrum of tracer in inertial confinement fusion implosion target is usually used to infer electron temperature, density, and the mixture of fuel and shell, it is necessary to study the relation between the characteristics of X-ray emission spectrum and the implosion process, which is helpful for inferring the implosion status. Under the condition of SGIII prototype, approximately 0.5% atomic percent of Ar atoms are doped in an indirectly driven implosion target, X-ray spectrum of Ar is numerically simulated. In this article, the influences of line re-absorption effect, tracer concentration, and profile of fuel plasma state on the emission spectrum are studied. The relation between the temporal evolution of the emission spectrum and the implosion process is also investigated. It is found that as the tracer concentration increases up to ～1%, the X-ray intensity is enhanced, but the influence of line re-absorption becomes severe. Temporal evolution shows that the peak time of Ar X-ray intensity is almost the same as that of neutron production (the former delays about 15 ps, which usually cannot be resolved). As is well known, the strong line emission occurs in the plasma with high temperature, high electron density, and proper ionization. The detailed analysis shows that at the peak emission time, as the core Ar plasma is over ionized, the main X-ray line emission region is located near the boundary region of the fuel, and this thin shell, whose thickness is about 4 μm and whose volume accounts for 56% of the total fuel plasma volume, emits the X-ray whose intensity is about 72% of the total line intensity. Therefore, the space-averaged plasma temperature and density, which are obtained by fitting the emission spectrum, mainly reflect the plasma state in this region.
Spectroscopic study on the laser-induced breakdown flame plasma
Authors: Liu Yu-Feng  , Zhang Lian-Shui  , He Wan-Lin  , Huang Yu  , Du Yan-Jun  , Lan Li-Juan  , Ding Yan-Jun  , Peng Zhi-Min  ,   State Key Laboratory of Power Systems, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China;,   College of Physics Science and Technology, Hebei University, Baoding 071002, China;,   School of Control and Computer Engineering, North China Electric Power University, Baoding 071003, China
Published: December 2020

The emission spectra from a flame-breakdown atmospheric pressure plasma generated by a nanosecond pulsed 1064 nm beam of Nd:YAG laser are investigated by using a PI-MAX-II intensified charge coupled device. The emission lines of the main elements, such as carbon, hydrogen, oxygen and nitrogen are identified according to the national institute of standards and technology database of atomic emission. It is found that the relative intensities of the atomic emission lines are different from each other under different combustion conditions by making a comparative analysis of the spectra of laser induced breakdown air plasma, alcohol burner flame plasma, and alcohol blast burner flame plasma. The obtained results in this work provide an experimental basis for applying the laser-induced breakdown technology to the combustion diagnostics, and have an important reference and significance for analyzing the characteristics of hydrocarbon fuel combusting in air.
Nanopore change law and mechanism of polyacrylonitrile based carbon fiber precursor in spinning process
Authors: Tang Hai-Tong  , Ao Yu-Hui  , Wang Cong  , Zhao Rui-Xue  , Gao Zhong-Min  , Meng Fan-Ling  ,   School of Chemistry and Bioscience, Changchun University of Technology, Changchun 130012, China;,   State Key Laboratory of Synthesis and Preparative Chemistry, Jilin University, Changchun 130012, China;,   College of Materials Science and Engineering, Jilin University, Changchun 130012, China
Published: December 2020

In this paper, we quantitatively characterize the morphological structure parameters including the nanopore size, shape, volume fraction, absolute number of nanopores and total prosity of polyacrylonitrile based carbon fiber precursor. Meanwhile, the change law and reason in the process of washing, drawing in washing, heat-densification, drawing in high pressure steam and hoting-stabilization are investigated. Results show that spinning drawing and high-temperature heat treatment make the prosity of fibers decline gradually in the process of fabrication. The result of micropore volume fraction Vi shows that at the beginning of the spinning and drawing in washing process the Vi of smaller nanopore which is less than 10 nm3 and the Vi of greater nanopore which is larger than 103 nm3 are 0.217 and 0.369, respectively, while these values sharply turn to 0.948 and 0.015 after the late spinning process of hoting-stabilization. The reason for this is not the increase of content of smaller nanopore content in the drawing process in high pressure steam and hoting-stabilization, but the sharp decrease of the greater nanopore content. The result about nanopore shape shows that the spinning multiple drawing in the process increases the axial (long-axis-to-short-axis) ratio of nanopores, while heat treatment over the glass transition temperature reduces the axial ratio of nanopore, and this shrinkage is more significant for smaller nanopores.
Electronic properties of doped hexagonal graphene
Authors: Tian Wen  , Yuan Peng-Fei  , Yu Zhuo-Liang  , Tao Bin-Kai  , Hou Sen-Yao  , Ye Cong  , Zhang Zhen-Hua  ,   School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114, China
Published: December 2020

Zigzag- and armchair-edged hexagonal graphenes are sandwiched between two Au electrodes to construct molecular nanodevices, and the effects of the orderly and locally doped with B, N, and BN for such graphene nanoflakes are considered, respectively. Based on the first-principles method, the electronic transport properties of these devices are investigated systematically. Our calculated results show that the using of B and BN to dope armchair-edged hexagonal graphenes can modulate the electronic transport properties significantly. Intrinsic and doped zigzag-hexagonal graphenes presents a semiconductoring behavior, and when it is doped with N and BN, there appears a negative differential resistance (NDR) phenomenon, especially for N-doping, and a very obvious NDR can be observed in zigzag-edged hexagonal grapheme: this might be important for developing molecular switches. The underlying causes for these findings are clearly elucidated by the transmission features and the doping-induced changes in electronic properties of a hexagonal graphene.
The effect of temperature on the mechanical properties of the diamond coating at the film-substrate interface
Authors: Jian Xiao-Gang  , Zhang Yun-Hua  ,   School of Mechanical Engineering, Tongji University, Shanghai 201804, China
Published: December 2020

The model of the diamond coating at the film-substrate interface is established by using the molecular dynamic method. The interaction between the atoms in this model is described by the Morse potential function and Tersoff potential function. Based on the above, we carry out the molecular dynamic simulation of the mechanical properties of the model in a temperature range from 0 to 800 K. The simulation results show that the tensile strength of diamond coating at the film-substrate interface presents a downward trend as the temperature rises from 0 to 800 K: the downward trend is evident when the temperature is in a range of 0-300 K, and the downward trend is smooth when the temperature is in a range of 300-800 K. Meanwhile, the variation of system energy with temperature presents a downward trend similar to the variation trend of the tensile strength.
Atomic configurations of dislocation cores in a small-angle grain boundary of 3C-SiC film
Authors: Cui Yan-Xiang  , Wang Yu-Mei  , Li Fang-Hua  ,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Published: December 2020

[110] images are taken for 3C-SiC/(001)Si hetero epitaxial films containing small-angle grain boundaries by using a 200 kV LaB6 filament high-resolution transmission electron microscope. Deconvolution processing is performed to transform the experimental images which do not represent intuitively the projected crystal structure into structure images. First, Si and C atomic columns with a distance of 0.109 nm are resolved in a perfect structure image region, and then recognized from each other by analyzing the image contrast change with sample thickness based on the pseudo-weak phase object approximation. Subsequently, two complex dislocation cores located in the vicinity of small-angle grain boundaries are obtained at an atomic level, and the atomic structure models are constructed and confirmed by matching the experimental images with the simulated ones. Hence, the atomic configurations of dislocation cores are derived from only a single experimental image with the average structure of perfect crystal known in advance. The formation of small-angle grain boundaries in 3C-SiC/Si with the occurence of complex dislocations in their vicinity is discussed.
Fluorescence resonance energy transfer between CdTe quantum dots and copper phthalocyanine
Authors: He Zhi-Cong  , Li Fang  , Li Mu-Ye  , Wei Lai  ,   School of Science, Wuhan Institute of Technology, Wuhan 430073, China;,   School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
Published: December 2020

The fluorescence resonance energy transfer in CdTe quantum dots (QDs)-copper phthalocyanine (CuPc) is investigated by ultrafast time-resolved spectroscopy technique equipped with femtosecond laser (780 nm, 76 MHz, 130 fs). The results show that the fluorescence lifetime of CdTe QDs decreases with the increase of CuPc concentration, and the energy transfer efficiency is found to increase with the increase of CuPc concentration. Moreover, the influence of the laser excitation power on the energy transfer efficiency is also studied. It is found that transfer efficiency decreases as excitation laser power increases, the physical mechanism is the thermal activation in the high power and the excited state transitions of high order induced by two-photon. The energy transfer efficiency can reach 43.8%, when the laser power is 200 mW, via two-photon excitation. This study indicates that the CdTe QDs-CuPc composite system has high potential as the third generation of photosensitizers.
First-principles study of electronic properties of MoSi2 thin films
Authors: Peng Qiong  , He Chao-Yu  , Li Jin  , Zhong Jian-Xin  ,   Hunan Key Laboratory for Micro-Nano Energy Materials and Devices, School of Physics and Optoelectronics, Xiangtan University, Xiangtan 411105, China
Published: December 2020

Electronic properties of tetragonal MoSi2 thin films are studied by the first-principles method. The results show that the MoSi2 film is always metallic, and its density of states and electronic structure are gradually close to their bulk counterpart as the film thickness increases. We further show that the three-atomic-layer film with the lowest energy is magnetic and has a magnetic moment of 0.33 B for its unit cell, and the film becomes non-magnetic when its thickness is more than three atomic layers. Moreover, we investigate the electronic properties of the three-atomic-layer MoSi2 films under unilateral and bilateral hydrogenation and find that the film with unilateral hydrogenation is magnetic and has a magnetic moment of 0.26 B, while the film with bilateral hydrogenation is non-magnetic. The spin polarizations for the films without hydrogenation and unilateral hydrogenation are 30% and 33%, respectively. These results suggest that three-atomic-layer MoSi2 film is metallic or magnetic when it is under suspension or grown on substrate, indicating its potential applications in nanoscale electronic and spintronic devices.
Room-temperature thermoelectric properties of GaN thin films grown by metal organic chemical vapor deposition
Authors: Wang Bao-Zhu  , Zhang Xiu-Qing  , Zhang Ao-Di  , Zhou Xiao-Ran  , Bahadir Kucukgok  , Na Lu  , Xiao Hong-Ling  , Wang Xiao-Liang  , Ian T. Ferguson  ,   Schoole of Information Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China;,   Department of Electrical and Computer Engineering, University of North Carolina at Charlotte, Charlotte NC 28223, USA;,   Department of Engineering Technology, University of North Carolina at Charlotte, Charlotte NC 28223, USA;,   Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

The GaN thin films with different doping concentrations are grown by metal organic chemical vapor deposition. Carrier concentrations, mobilities and Seebeck coefficients of the GaN thin films are measured by Hall and Seebeck system at room temperature. The power factor and the thermoelectric figure of merit are calculated by experimental and theoretical data. The mobility and Seebeck coefficient of GaN thin film decrease with the increase of carrier concentration. The conductivity of GaN thin film increases with the increase of carrier concentration. The Seebeck coefficient of GaN thin film varies from 100 to 500 μV/K, depending on carrier concentration. The highest power factor is 4.72×10-4 W/mK2 when the carrier concentration is 1.60×1018 cm-3. The thermal conductivity of GaN thin film decreases with the increase of carrier concentration due to the increase of phonon scattering. The largest thermoelectric figure of merit of the GaN thin film at room temperature is 0.0025 when the carrier concentration is 1.60×1018 cm-3.
Organic memristive devices based on DNA embedded in silver nanoparticles layer
Authors: Wang Yuan  , Dong Rui-Xin  , Yan Xun-Ling  ,   Key Laboratory of Optical Communication Science and Technology of Shandong Province, School of Physical Science and Information Engineering, Liaocheng University, Liaocheng 252059, China
Published: December 2020

Two-terminal electrical bistable device is fabricated with structure “Al/deoxyribonucleic acid-cetyltrimethylam- monium bromide/silver nanoparticles/deoxyribonucleic acid-cetyltrimethylammonium bromide/indium tin oxide”, and I-V curves are measured. The results show that the conductivity and the memristive characteristics are significantly improved by the embedding Ag nanoparticles layer. The optimal particle diameters are in a range of 15 - 20 nm, and the maximum on/off current ratio can reach 103. It is also found that I-V characteristic of the device depends on the sweeping voltage amplitude VA. As VA increases, switching voltages (VSET, VRESET) and the on/off current ratio ION/IOFF increase. Furthermore, the transition between high-and low-resistance-state depends on the direction of the applied electric field, which shows that the device possesses polarity.
Experimental study on multicolor two-photon excited fluorescence microscopy
Authors: Qiu Jun-Peng  , Liang Run-Fu  , Peng Xiao  , Li Ya-Hui  , Liu Li-Xin  , Yin Jun  , Qu Jun-Le  , Niu Han-Ben  ,   Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China;,   School of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071, China
Published: December 2020

Two-photon excited fluorescence (TPEF) microscopy is a nonlinear optical microscopy technique. The advantages of TPEF microscopy include high temporal and spatial resolutions, high signal-to-noise ratio and inherent three-dimensional sectioning. In traditional TPEF microscopy, a wavelength tunable ultrashort pulsed laser is used as an excitation source. In practical applications, sample usually contains various fluorophores or unknown components. Therefore the excitation wavelength of the ultrafast laser has to be tuned to achieve optimal excitation efficiencies of various fluorophores. In order to acquire the fluorescent signals of different fluorophores simultaneously, we develop a multicolor TPEF microscope system based on a supercontinuum laser source. In experiments, TPEF images of Lily rhizome sample slide stained by two fluorescent dyes with different excitation and emission wavelengths are obtained without tuning the wavelength. Experimental results show that the high-contrast TPEF images of the sample with various fluorophores can be obtained simultaneously by using the multicolor TPEF microscope compared with by using traditional TPEF microscopy. The system is simple in structure, easy in operation, and can provide rich information about the sample, which allows it to be widely used in life and material sciences.
An information spreading model based on relative weight in social network
Authors: Wang Jin-Long  , Liu Fang-Ai  , Zhu Zhen-Fang  ,   School of Information Science and Engineering, Shandong Normal University, Jinan 250014, China;,   Shandong Provincial Key Laboratory for Distributed Computer Software Novel Technology, Jinan 250014, China;,   School of Information Science and Electric Engineering, Shandong Jiaotong University, Jinan 250357, China
Published: December 2020

In this paper, we first introduce a mutual influence function among network nodes based on characteristics of information spreading in online social network. Then we put forward an information spreading model based on relative weight, analyze the propagation path and process of the network, and discuss the influence on different paths. Finally, the simulation experiments of the traditional SIR model and the model in this paper are conducted with six different network topologies. Results show that the two models have no significant difference in homogeneous networks, but there are significant differences in inhomogeneous networks. This result shows that the information spreading is influenced by the status of spreading nodes, and also shows that the real networks like Twitter and Sina Microblog have certain similarity in topological structure.
Internal stray radiation measurement for cooled infrared imaging systems
Authors: Chang Song-Tao  , Sun Zhi-Yuan  , Zhang Yao-Yu  , Zhu Wei  ,   Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China;,   University of Chinese Academy of Sciences, Beijing 100049, China
Published: December 2020

Stray radiation is an important indicator for the infrared optical systems involved in the process of designing and testing. In order to measure the internal stray radiation in infrared imaging systems, a method based on radiometric calibration is proposed, and its rationality is verified by theoretical analysis and experiments. Firstly, the model of radiometric calibration without lens, in other words the detector for absorbing the radiation flux directly from the calibration reference source, is developed to show the influence of internal factors of the detector on the system output. Then it is compared with the results of calibration of the infrared system with a lens to obtain the system output results from the optical system, namely the internal stray radiation caused by the optical system. Finally, experiments are performed to prove the correctness of the theories proposed in this paper. The proposed method has some advantages, such as simple operation, low demand for the experimental conditions, and the capability of measuring the internal stray radiation accurately. It can be used to guide the stray radiation suppression in the process of infrared system designing, to verify the stray radiation analysis results, and to test whether the stray radiation level meets the practical requirements.
Research on distributed intrinsic Fabry-Perot sensors
Authors: Gui Xin  , Hu Chen-Chen  , Xie Ying  , Li Zheng-Ying  ,   National Engineering Laboratory for Fiber Optic Sensing Technology, Wuhan University of Technology, Wuhan 430070, China;,   Key Laboratory of Fiber Optic Sensing Technology and Information Processing, Ministry of Education, Wuhan University of Technology, Wuhan 430070, China
Published: December 2020

This paper introduces a kind of single mode-multimode-single mode intrinsic Fabry-Perot interferometer (SMS-IFPI). We optimize the sensing length of the graded-index multimode fiber (GI-MMF), insertion loss, and multiplexing capability through the analysis and simulation of the optical field distribution in the GI-MMF. Experiment proves that the insertion loss of a single sensing unit from the optimized cascade SMS-IFPI may be decreased from 4 dB to 0.83 dB. Testing the response characteristics of SMS-IFPI temperature sensors in the distribution under the condition of different temperature, the experimental results show that each SMS-IFPI can have better sensitivity and linearity.
Study of X-ray spectrum emitted due to the impact of 129Xeq+ on different ion's charge on Au
Authors: Liang Chang-Hui  , Zhang Xiao-An  , Li Yao-Zong  , Zhao Yong-Tao  , Mei Ce-Xiang  , Zhou Xian-Ming  , Xiao Guo-Qing  ,   Ion beam & Optical Physical joint Laboratory of Xianyang Normal University and Institute of Modern Physics, Chinese Academy of Sciences, Xianyang 712000, China;,   Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
Published: December 2020

We report the experiment data of X-ray spectra produced by the impact of Xeq+ (q=10, 15, 20, 26) with 2.4 MeV kinetic energy on Au surface in the National Laboratory of Heavy Ion Research Facility in Lanzhou. Results show that there is different broadening of Au M X-ray owing to multiply ionized effect in the collision with heavy ions, the degree of ionization mainly depends on the distribution of the electronic states in the ions' outer shell. The yield of X-ray is calculated and compared with BEA (binary encounter approximation) model, and the effect of ion charge state on the X-ray yield is also discussed.
Study on the phase-extracting method of self-mixing signal based on empirical mode decomposition
Authors: Zhang Yu-Yan  , Zhou Hang  , Yan Meisu  ,   Institute of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China;,   Key Lab of Measurement Technology and Instrumentation of Hebei Province, Qinhuangdao 066004, China
Published: December 2020

In order to achieve precise extraction of the phase with a light feedback mechanism, based on empirical mode decomposition (EMD) algorithm, an adaptive phase extraction method is proposed in this paper. First of all, the EMD algorithm is acted on the self-mixing interference (SMI) mixed noise signals, then using the principle of HHT to extract the instantaneous phase information in the SMI signal in time and retrieve the true phase of the object from the wrapped phase. In this paper, the phase extraction algorithm based on EMD are simulated under different optical feedback conditions. Finally, an experimental setup based on SMI has been given for demonstration. Experimental results show that this method is correct in principle and can be used in the precise extraction and its maximum error is less than 1.6 rad. The simulation results are consistent with the experimental data, which show the effectiveness of the proposed method.
Four-phase closure algorithm for coherent field imaging
Authors: Cao Bei  , Luo Xiu-Juan  , Si Qing-Dan  , Zeng Zhi-Hong  ,   Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119, China
Published: December 2020

According to the realization principle of phase closure in coherent field imaging, a new four-phase closure (FPC) algorithm is proposed for T-array multi-beam transmitter system. A type of four-item measurement radio of closure phase is first defined, and then the validity of FPC is confirmed in cancelling out the random atmospheric phase aberrations as well as eliminating atmospheric scintillation effect on degradation of the reconstructed image. Simulations prove the effectiveness of FPC, providing a new approach in removing atmospheric aberrations for multi-beam coherence field imaging.
Analysis on the simplified optic coma effect on spectral image inversion of coded aperture spectral imager
Authors: Liu Yang-Yang  , Lü Qun-Bo  , Wu Ge  , Pei Lin-Lin  , Wang Jian-Wei  ,   Academy of Opto-electronics, Chinese Academy of Sciences, Beijing 100094, China
Published: December 2020

With the novel spectrum imaging technology development in recent years, the push-broom coded-aperture spectral imaging (PCASI) shows the advantages of high throughput, high SNR, high stability etc. This coded-aperture spectral imaging utilizes fixed-code templates and push-broom mode, which can realize high-precision reconstruction of spatial and spectral information. But during optical lens designing, manufacturing and debugging, there inevitably exist some minor coma errors. Even minor coma errors can reduce image quality. In this paper, we simulate the system optical coma error which influences the quality of reconstructed image, analyze the variantion of the coded aperture in different optical coma effect, and then propose an accurate curve for image quality and optic coma quality in 255× 255 coded template, which provides important references for the design and development of push-broom coded-aperture spectrometer.
Generation of octave-spanning super-continuum in tapered single mode fibre pumped by femtosecond Yb:YCOB laser
Authors: Jia Yu-Lei  , Zhu Zheng  , Han Hai-Nian  , Tian Wen-Long  , Xie Yang  , Zhang Long  , Wei Zhi-Yi  ,   College of Science, China University of Petroleum, Qingdao 266580, China;,   Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;,   School of Physics and Optoelectronic Engineering, Xidian University, Xi'an 710071, China
Published: December 2020

It is a pivotal step in the measurement of carrier-envelope phase offset frequency in optical femtosecond frequency combs that a stable octave-spanning super-continuum spectrum is generated. In this paper, a home-made Yb:YCOB femtosecond laser pulse is led into a tapered fiber in which some nonlinear effects like self pulse modulation are generated and the four-wave mixing is made to broaden a spectrum to more than one octave-spanning. A Yb:YCOB oscillator emits 130 fs, 620 mW and 76.8 MHz laser pulses, the center wavelength at 1052 nm. Such pulses are focused into a tapered single-mode fiber, and then more than one octave-spanning supercontinuum from 550 nm to 1350 nm has been produced. The coupling efficiency can reach 52% when 323 mW SC laser pulses are detected. Based on the experimental result, a new optical comb will be built with the Yb:YCOB solid state laser as the light source.
Influence of Raman scattering effect and self-steepening effect on the propagation characteristic of picosecond solitons
Authors: Yu Yu  , Jia Wei-Guo  , Yan Qing  , Ke Neimule  , Zhang Jun-Ping  ,   School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China
Published: December 2020

By solving the higher-order nonlinear Schrödinger equation (NLSE), including Raman gain and self-steepening effect, the influence of the combined effect of Raman gain and self-steepening on the propagation characteristic of soliton pulse is simulated by the software of MATLAB. Results show that self-steepening effect can produce temporal shifts of the soliton and also can lead to the breakup of higher-order solitons through the phenomenon of soliton fission. Meanwhile, the Raman gain changes the propagation characteristic of optical soliton and inhibits the self-steepening effect, resulting in the increase in pulse width, and the decrease in pulse offset. As a result, the required propagation distance for higher-order soliton decaying into fundamental solitons is increased under the condition of Raman gain.
Robust sub-regional Frost beamforming based on the signal subspace reconstruction
Authors: Fan Zhan  , Liang Guo-Long  , Fu Jin  , Wang Yan  ,   Acoustic Science and Technology Laboratory, Harbin 150001, China;,   College of Underwater Acoustic Engineering, Harbin Engineering University, Harbin 150001, China
Published: December 2020

For the problem of broadband beamforming in a subregion of interest, a robust Frost beamforming algorithm is derived by reconstructing the signal subspace. The basic idea of the proposed algorithm is to extract the characteristic components of the signal of interest (SOI) from the estimated signal-plus-interference subspace by a matrix filter first, then employ these characteristic components to reconstruct the signal subspace, and finally construct a set of linearly constrained minimum variance (LCMV) constraints to protect the SOI components. Compared with some other robust Frost beamformers, the proposed algorithm has a significant advantage, i.e., its steering-angle and band are effective to match the SOI without prior information. Hence, the performance of the proposed algorithm is almost always close to the optimal value across the whole region of interest. Theoretical analysis and simulation results validate the effectiveness of the proposed algorithm.