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Experimental Violation of Multiple-Measurement Time-Domain Bell's Inequalities
TANG Jian-Shun, LI Yu-Long, LI Chuan-Feng**, XU Jin-Shi, CHEN Geng, ZOU Yang, ZHOU Zong-Quan, GUO Guang-Can
Chin. Phys. Lett. 2011, 28 (6):
060304
.
DOI: 10.1088/0256-307X/28/6/060304
In the original time-domain Bell's inequalities (Leggett-Garg-type inequalities), the physical objective is measured at three time points. When more time points are chosen, several methods can be used to extend these inequalities. We experimentally demonstrate the violation of these extended inequalities using single photons from a self-assembled quantum dot. In general, for each extension, the quantity by which the quantum-mechanics value exceeds the classical limit becomes larger as the number of measurement time points increases. This quantity has a maximum value for the extensions that have the same number of measurement time points. Furthermore, we evaluate the noise tolerance for these extensions with a quantity that is related to the number of standard deviations by which the experimental result surpasses the classical limit.
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Flat Crystal x-ray Spectrometer for Quantitative Spectral Measurement in the 2–5keV Region
ZHAO Yang**, WEI Min-Xi, DENG Bo, ZHU Tuo, HU Zhi-Min, XIONG Gang, SHANG Wan-Li, KUANG Long-Yu, YANG Guo-Hong, ZHANG Ji-Yan, YANG Jia-Min
Chin. Phys. Lett. 2011, 28 (6):
060701
.
DOI: 10.1088/0256-307X/28/6/060701
A technique of flat crystal x-ray spectrometer for quantitative spectral measurement is described. For the flat crystal spectrograph geometry, the quantitative reduction of relating the CCD counts back to the photon flux from the x-ray source is established. The absolute calibrations of the integral diffraction coefficients of the crystal and the CCD sensitivity make it possible to measure absolute photons flux within the energy range of 2000–5000 eV. The uncertainty analysis of the calibrations is carried out to obtain the energy resolved uncertainties of crystal and CCD. Thus, the experimental spectra with spectral resolved intensity uncertainties are available. Then, a performing experiment of laser-produced Ti plasma is carried out and the absolute x-ray spectra with intensity uncertainty less than 8.5% are obtained. The technique is promising for absolute spectral measurement of high temperature plasmas in a kilo-electron-volt region.
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Improvement on Temperature Measurement of Cold Atoms in a Rubidium Fountain
LÜ, De-Sheng**, QU Qiu-Zhi, WANG Bin, ZHAO Jian-Bo, LIU Liang**, WANG Yu-Zhu
Chin. Phys. Lett. 2011, 28 (6):
063201
.
DOI: 10.1088/0256-307X/28/6/063201
The time-of-flight (TOF) method is one of the most common ways to measure the temperature of cold atoms. In the cold atomic fountain setup, the geometry of the probe beam will introduce the measurement errors to the spatial distribution of cold atomic cloud, which will lead to the measurement errors on atomic temperature. Using deconvolution, we recover the atomic cloud profile from the TOF signal. Then, we use the recovered signals other than the TOF signals to obtain a more accurate atomic temperature. This will be important in estimating the effects of cold atom collision shift and the shift due to transverse cavity phase distribution on an atomic fountain clock.
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Laser Cooling of 87Rb to 1.5µK in a Fountain Clock
WANG Bin, LÜ, De-Sheng**, QU Qiu-Zhi, ZHAO Jian-Bo, LI Tang, LIU Liang, **, WANG Yu-Zhu
Chin. Phys. Lett. 2011, 28 (6):
063701
.
DOI: 10.1088/0256-307X/28/6/063701
We report an experiment on the adiabatic cooling of 87Rb atoms in an atomic fountain to a temperature as low as 1.5 μK, which is roughly twice the recoil temperature. The atomic fountain has the (1,1,1) optical geometry for cooling and launching of cold atoms. The atoms are first cooled in an optical molasses of 6 beams to 3.4 μK by polarization gradient geometry and then are adiabatically cooled by decreasing the intensity of laser from 1.8Is per beam to zero in 1 ms during the launching of cold atoms. We also study the dependences of atomic temperature on different laser parameters. The method we used is useful in any cold atom physics experiment.
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The research of Digital Holographic Object Wave Field Reconstruction in Image and Object Space
LI Jun-Chang**, PENG Zu-Jie, FU Yun-Chang
Chin. Phys. Lett. 2011, 28 (6):
064201
.
DOI: 10.1088/0256-307X/28/6/064201
For conveniently detecting objects of different sizes using digital holography, usual measurements employ the object wave transformed by an optical system with different magnifications to fit charge coupled devices (CCDs), then the object field reconstruction involves the diffraction calculation of the optic wave passing through the optical system. We propose two methods to reconstruct the object field. The one is that, when the object is imaging in an image space in which we reconstruct the image of the object field, the object field can be expressed according to the object-image relationship. The other is that, when the object field reaching CCD is imaged in an object space in which we reconstruct the object field, the optical system is described by introducing matrix optics in this paper. The reconstruction formulae which easily use classic diffraction integral are derived. Finally, experimental verifications are also accomplished.
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Preprocessing-Free All-Optical Clock Recovery from NRZ and NRZ-DPSK Signals Using an FP-SOA Based Active Filter
WANG Fei, **, ZHANG Xin-Liang, YU Yu, XU En-Ming
Chin. Phys. Lett. 2011, 28 (6):
064208
.
DOI: 10.1088/0256-307X/28/6/064208
We demonstrate a simple scheme to perform all-optical clock recovery from the input nonreturn-to-zero (NRZ) and nonreturn-to-zero differential phase shifted keying (NRZ-DPSK) data, which are avoided using any preprocessing measures. A multi-quantum-well Fabry-Pérot semiconductor optical amplifier plays the dual role of the data format converter and the clock recovery device. Using this scheme, a stable and low jitter 35.80-GHz optical clock pulse sequence is directly extracted out from the input NRZ or NRZ-DPSK data. This scheme has some distinct advantages such as simple device fabrication, transparence to data format, multiwavelength operation, free preprocessing and convenient tuning. Potential powerful adaptability of this scheme is very important for next-generation optical networks, in which there exist various modulation formats and the used devices are required to be transparent to data formats.
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Comparative Studies on the Laser Damage Resistance of Ta2O5 and Nb2O5 Films Performed under Different Electron Beam Currents
XU Cheng, **, XU Lin-Min, ZHANG Han-Zhuo, QIANG Ying-Huai, ZHU Ya-Bo, LIU Jiong-Tian, SHAO Jian-Da
Chin. Phys. Lett. 2011, 28 (6):
064211
.
DOI: 10.1088/0256-307X/28/6/064211
Ta2O5 and Nb2O5 films are deposited by conventional e−beam method under different electron beam currents. The optical transmittance, chemical composition, absorption, scattering, surface topography and laser-induced damage threshold (LIDT) of the films are comparatively studied. It is shown that the increase of electron beam current results in a decrease of the optical transmittance and stoichiometry, whereas it increases the absorption, scattering and rms roughness for both Ta2O5 and Nb2O5 films. However, the LIDT increases first and then decreases with the increase of electron beam current. In addition, the annealing improves the optical transmittance, stoichiometry and LIDT for the two kinds of films. Both the effects of electron beam current and annealing on the LIDT can be mainly attributed to three factors: substoichiometric defects, structural defects and adhesive force. Furthermore, the comparative results indicate that the laser damage resistance of Ta2O5 is lower than that of Nb2O5.
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Entangling a Series of Trapped Ions by Moving Cavity Bus
ZHANG Miao, JIA Huan-Yu, WEI Lian-Fu, **
Chin. Phys. Lett. 2011, 28 (6):
064213
.
DOI: 10.1088/0256-307X/28/6/064213
Entangling multiple qubits is one of the central tasks of quantum information processing. We propose an approach to entangle a number of cold ions (individually trapped in a string of microtraps) by a moved cavity. The cavity is pushed to include the ions one by one with a uniform velocity and thus the information stored in former ions could be transferred to the latter ones by such a moving cavity bus. Since the positions of the trapped ions are precisely located, the strengths and durations of the ion-cavity interactions can be exactly controlled. As a consequence, by properly setting the relevant parameters, typical multi-ion entangled states, e.g., W state for 10 ions, could be deterministically generated. The feasibility of the proposal is also discussed.
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Space-Resolved Diagnosis for Electron Temperature of Laser-Produced Aluminum Plasma
ZHAO Yang**, DENG Bo, XIONG Gang, HU Zhi-Min, WEI Min-Xi, ZHU Tuo, SHANG Wan-Li, LI Jun, YANG Guo-Hong, ZHANG Ji-Yan, YANG Jia-Min
Chin. Phys. Lett. 2011, 28 (6):
065201
.
DOI: 10.1088/0256-307X/28/6/065201
The K−shell emission spectra of laser-produced aluminum plasma are measured by a space-resolved spectrometer consisting of a flat crystal spectrometer with a 20 μm wide space−resolved slit. By using the approximation of the steady collisional-radiative equilibrium model, the interstage line intensity ratios of Ly-α resonance line to He−α resonance line are given as a function of electron temperature. The spectra profiles are decomposed to resonance line and the overlapped high-order satellites manifold. Thus reliable electron temperature is deduced from the interstage line intensity ratios of the decomposed resonance lines. The results of spaced-resolved temperature are compared with the hydrodynamic simulations. The diagnostics of electron temperature for laser-produced plasma is developed.
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Charge and Mass Effects on Low Energy Ion Channeling in Carbon Nanotubes
LI Yong, ZHENG Li-Ping, ZHANG Wei**, XU Zi-Jian**, REN Cui-Lan, HUAI Ping, ZHU Zhi-Yuan
Chin. Phys. Lett. 2011, 28 (6):
066101
.
DOI: 10.1088/0256-307X/28/6/066101
Channeling phenomena of He, Ne, Ar and Kr ions at energy (200–5000 eV) in single-wall carbon nanotubes (SWCNTs) are investigated by molecular dynamics simulation with analytical potentials. The critical angles for the particles to be channeled in an SWCNT are analyzed. In the incident energy range of 200–5000 eV, it is found that the ion energy dependence of the critical angle obeys an improved Lindhard equation which is closely related to the ratio of nuclear charge number to atomic mass Z/M. The critical angle for different types of ions channeling in SWCNTs is determined by both the atomic nuclear charge and mass.
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Two-Dimensional Cavity Resonant Modes of Si Based Bragg Reflection Ridge Waveguide
CHEN San, **, Lu Hong-Yan, CHEN Kun-Ji**, XU Jun, MA Zhong-Yuan, LI Wei, HUANG Xin-Fan
Chin. Phys. Lett. 2011, 28 (6):
066803
.
DOI: 10.1088/0256-307X/28/6/066803
Si-based ridge-waveguides with Bragg reflectors are fabricated based on our method. Three resonant peaks could be obviously identified from the photoluminescence spectra, and field patterns of these resonant peaks, simulated by the finite difference time domain (FDTD) method, confirm that these peaks originate from cavity resonances. The resonant wavelengths and spatial angular distribution are given by the resonant models, which agree well with the experimental data. Experimentally, a simple method is proposed to testify the experimental and theoretical results. Such devices based on Bragg reflectors may have potential applications in light-emitting diodes, lasers and integrated photonic circuits.
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First-Principles Calculations of the Structural, Electronic and Optical Properties of BaZrxTi1−xO3 (x=0, 0.25, 0.5, 0.75)
ZHAO Xin-Yin, WANG Yue-Hua**, ZHANG Min, ZHAO Na, GONG Sai, CHEN Qiong
Chin. Phys. Lett. 2011, 28 (6):
067101
.
DOI: 10.1088/0256-307X/28/6/067101
The pseudo-potential plane wave (PP-PW) method with the generalized gradient approximation (GGA) is used to calculate the structural, electronic and optical properties of cubic and tetragonal BaZrxTi1−xO3(BZT) (x= 0, 0.25, 0.5, 0.75). The calculated structural parameters are found to be in good agreement with the experimental data. The energy band structure density of states (DOS) are obtained, which indicates that the Zr substitute can induce the band gap widening of BaTiO3. Furthermore, their optical properties are also calculated and analyzed in detail. It is shown that the dielectric imaginary part of BZT decreases as x (Zr concentration) increases.
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A Comparative Investigation on the JT Effect in Triangular Compounds of NaMnO2, NaNiO2 and NaTiO2
OUYANG Sheng-De, QUAN Ya-Min, LIU Da-Yong, ZOU Liang-Jian**
Chin. Phys. Lett. 2011, 28 (6):
067102
.
DOI: 10.1088/0256-307X/28/6/067102
We present a study on the Jahn–Teller (JT) distortions of the TiO6, NiO6 and MnO6 complexes in NaTiO2, NaNiO2 and NaMnO2 triangular compounds with a C2/m structure. The JT vibronic normal modes are found to be Q3, Q'4 and Q6 by the group symmetry on the C2/m structure. The magnitude of the normal coordinates (Q3, Q'4, Q6) and the structural parameters of distorted octahedra MO6 (M=Ti, Ni, Mn) are obtained and in good agreement with experimental data. The energy level splitting of 3d orbitals and the highest occupied molecular orbital (HOMO) character in the MO6 complex are also calculated in accordance with the JT distortions. These results provide a first insight into the groundstate and magnetic properties of distorted triangular compounds AMO2.
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Effect of Water Concentration on the Characterization of Sprayed Cd0.5Zn0.5S Films
Sur S., Ö, ztürk Z., Ö, zta&scedil, M.**, Bedir M., Ö, zdemir Y.
Chin. Phys. Lett. 2011, 28 (6):
067103
.
DOI: 10.1088/0256-307X/28/6/067103
Cd0.5Zn0.5S film samples are prepared by a spray pyrolysis technique using aqueous solutions of CdCl2, ZnCl2, SC(NH2)2 and deionized water, which are atomized using compressed air as the carrier gas onto glass substrates with different water (H2O) concentrations. H2O is used as the activator. The prepared films are characterized by means of XRD and UV−VIS spectroscopy. Experimental results reveal that the structures and properties of the films are greatly affected by the H2O content. Water in a certain range of concentrations promotes the formation of the Cd0.5Zn0.5S films and improves the properties of the films.
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Voronoi Structural Evolution of Bulk Silicon upon Melting
ZHANG Shi-Liang, ZHANG Xin-Yu, WANG Lin-Min, QI Li, ZHANG Su-Hong, ZHU Yan, LIU Ri-Ping**
Chin. Phys. Lett. 2011, 28 (6):
067104
.
DOI: 10.1088/0256-307X/28/6/067104
The Voronoi structural evolution of silicon upon melting is investigated using a molecular dynamics simulation. At temperatures below the melting point, the solid state system is identified to have a four-fold coordination structure 〈4,0,0,0〉. As the temperature increases, the five−fold coordination 〈2,3,0,0〉 and six−fold coordination structures 〈2,2,2,0〉 and 〈0,6,0,0〉 are observed. This is explained in terms of increasing atomic displacement due to thermal motion and the trapping of the moving atoms by others. At temperatures above the melting point, nearly all of the four-fold coordination structures grows into multiple-fold coordination ones.
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Characteristics of Off-Chip Millimeter-Wave Radiation from Serial Josephson Junction Arrays
WANG Zheng**, FAN Bin, ZHAO Xin-Jie, YUE Hong-Wei, HE Ming, JI Lu, YAN Shao-Lin, FANG Lan, Klushin A. M.
Chin. Phys. Lett. 2011, 28 (6):
067401
.
DOI: 10.1088/0256-307X/28/6/067401
We investigate the self-emissions from serial high-temperature superconductor bicrystal Josephson junction arrays embedded in a quasi-optical resonator. A bicrystal substrate is used as a dielectric resonator antenna, which increases the coupling strength between the junction array and the electromagnetic (EM) wave. Both three-dimension (3D) electromagnetic simulations and experiments are performed. Strong off-chip radiations are measured from the junction array at 78 GHz and 78 K. The proposed method and the experimental results are important for millimeter wave applications in junction arrays.
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Fabrication and Properties of Aligned Sr0.6K0.4Fe2As2 Superconductors by High Magnetic Field Processing
GAO Zhao-Shun, ZHANG Xian-Ping, WANG Dong-Liang, QI Yan-Peng, WANG Lei, CHENG Jun-Sheng, WANG Qiu-Liang, MA Yan-Wei**, AWAJI Satoshi, WATANABE Kazuo
Chin. Phys. Lett. 2011, 28 (6):
067402
.
DOI: 10.1088/0256-307X/28/6/067402
We fabricated a c−axis aligned Sr0.6K0.4Fe2As2 superconductor using a two−step magnetic field procedure. The effect of the magnetic fields on the structure and superconducting properties of Sr0.6K0.4Fe2As2 is investigated using x−ray diffraction and magnetic measurements. The degree of orientation of the samples is about 0.39 for the c axis and 0.51 for ab-plane orientation, as evaluated from the Lotgering factor of x-ray diffraction. This technology may be useful in a variety of potential applications, including preparing iron-based superconducting bulks and wires with high critical currents.
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Effect of a Boron Underlayer on the Ordering and Orientation of Sputtered FePt Film
LI Yong-Le, HUANG An-Ping, FENG Tang-Fu, CHEN Qiang, SHU Xiao-Lin, CHEN Jun-Yang, CHEN Zi-Yu, **
Chin. Phys. Lett. 2011, 28 (6):
067502
.
DOI: 10.1088/0256-307X/28/6/067502
FePt multilayer films with a boron underlayer are prepared on Si (100) substrates using magnetron sputtering and vacuum annealing is carried out to obtain the hard magnetic L10 phase. According to the microstructural and magnetic measurement results, the ordering of the FePt films is facilitated at low annealing temperatures while it is blocked at high ones by introducing boron. Moreover, (001) orientation of the samples is obviously improved by inserting a boron underlayer, which is further confirmed by the MFM analysis. The relevant mechanism is discussed by considering the diffusion of boron atoms and the consequential in-plane tensile stress.
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Enhanced Magnetic and Ferroelectric Properties and Current-Voltage Hysteresis by Addition of La and Ti to BiFeO3 on 0.7%Nb−SrTiO3
CHANG Hong, **, ZHAO Yong-Gang
Chin. Phys. Lett. 2011, 28 (6):
067503
.
DOI: 10.1088/0256-307X/28/6/067503
By adding La and Ti, we improve the magnetic and ferroelectric properties of Bi0.8La0.2Fe0.92Ti0.08O3 and Bi0.8La0.2FeO3 films on 0.7%Nb−SrTiO3. In Bi0.8La0.2Fe0.92Ti0.08O3 and Bi0.8La0.2FeO3, the saturation magnetization and the coercivity are several times higher than those in BiFeO3. The La and Ti additions reduce the leakage current, and increase the remnant electric polarization. A resistance switching is observed in Bi0.8La0.2Fe0.92Ti0.08O3/0.7%Nb−SrTiO3 and Bi0.8La0.2FeO3/0.7%Nb−SrTiO3 interfaces. Also, it is observed that Bi0.8La0.2Fe0.92Ti0.08O3/0.7%Nb−SrTiO3 has a wider current−voltage hysteresis and a larger resistance difference than Bi0.8La0.2FeO3/0.7%Nb−SrTiO3. In the interface of Bi0.8La0.2Fe0.92Ti0.08O3/0.7%Nb−SrTiO3, the ratio of high to low resistance is 103 and 105 times, at 300 K and 10 K, respectively. The voltage pulses can switch the resistance to vary in the 2 states. The transport mechanisms show that a trap−controlled space-charge-limited current induces current-voltage hysteresis and resistance switching. The current of Bi0.8La0.2Fe0.92Ti0.08O3/0.7%Nb−SrTiO3 decays with the Curie–Von Schweidler law.
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A Wide-Band Metamaterial Absorber Based on Loaded Magnetic Resonators
GU Chao, QU Shao-Bo, **, PEI Zhi-Bin, MA Hua, XU Zhuo, BAI Peng, PENG Wei-Dong, LIN Bao-Qin
Chin. Phys. Lett. 2011, 28 (6):
067808
.
DOI: 10.1088/0256-307X/28/6/067808
A wide-band polarization-insensitive and wide-angle metamaterial absorber based on loaded magnetic resonators is presented. The unit cell of this absorber consists of a magnetic resonator loaded with lumped resistances, a dielectric substrate and a back metal film. Theoretical and simulated results show that this absorber has a wide-band strong absorption for the incident wave from 3.87 GHz to 21.09 GHz. Simulated absorbance values under loading and unloading conditions indicate that electrocircuit's resonances are more stable than electromagnetic resonances and thus can be used to realize wide-band absorption. Simulated absorbance values under different polarization angles and different angles of incidence indicate that this absorber is polarization-insensitive and wide-angle. It may have potential applications in military fields.
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Reaction Mechanism of Al and N in Diamond Growth from a FeNiCo-C System
LI Shang-Sheng, LI Xiao-Lei, MA Hong-An, SU Tai-Chao, XIAO Hong-Yu, HUANG Guo-Feng, LI Yong, ZHANG Yi-Shun, JIA Xiao-Peng, **
Chin. Phys. Lett. 2011, 28 (6):
068101
.
DOI: 10.1088/0256-307X/28/6/068101
It is significant to investigate the action of nitrogen getters, which are used to synthesize type-IIa large diamond single crystals under high pressure and high temperature (HPHT). The reaction mechanism of Al as a nitrogen getter and N in the HPHT alloy solvent is still indeterminate at present. In order to investigate the reaction of Al and N in the HPHT alloy solvent, Al and AlN are respectively added to the system of Fe55Ni29Co16−C (wt%, abbr. FeNiCo-C) for the synthesis of diamonds at about 5.5 GPa and 1600 K. The concentration of nitrogen in the diamonds is characterized by a micro Fourier transform infrared (micro-FTIR) spectrometer. The experimental results show that cN decreases when Al is added to the FeNiCo-C system. However, it increases when AlN is added. A reversible reaction confirms that Al and N can react and form AlN, simultaneously AlN can be decomposed into Al and N in the HPHT alloy solvent. Therefore the mechanism of eliminating the nitrogen of nitrogen getter Al is realized in detail.
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Epitaxy of an Al-Droplet-Free AlN Layer with Step-Flow Features by Molecular Beam Epitaxy
PAN Jian-Hai, WANG Xin-Qiang**, CHEN Guang, LIU Shi-Tao, FENG Li, XU Fu-Jun, TANG Ning, SHEN Bo***
Chin. Phys. Lett. 2011, 28 (6):
068102
.
DOI: 10.1088/0256-307X/28/6/068102
We investigate epitaxy of AlN layers on sapphire substrates by molecular beam epitaxy. It is found that an atomically flat surface can be obtained under Al-rich conditions at growth temperature of 780 °C. However, the growth window to obtain an Al−droplet-free surface is too narrow to be well-controlled. However, the growth window can be greatly broadened by increasing the growth temperature up to 950 °C, where an Al-droplet-free surface with a step-flow feature is obtained due to the enhanced re-evaporization rate and migration ability of Al adatoms. The samples grown at the higher temperature also show a higher crystalline quality than those grown at lower temperatures.
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Quantitatively Exploring the Effect of a Triangular Electrode on Performance Enhancement in a 4H-SiC Metal-Semiconductor-Metal Ultraviolet Photodetector
CHEN Bin**, YANG Yin-Tang, CHAI Chang-Chun, ZHANG Xian-Jun
Chin. Phys. Lett. 2011, 28 (6):
068501
.
DOI: 10.1088/0256-307X/28/6/068501
A model of novel triangular electrode metal-semiconductor-metal (TEMSM) and conventional electrode metal-semiconductor-metal (CEMSM) detectors is established by utilizing the ISE-TCAD simulator. By comparing the simulated results of TEMSM and CEMSM with experimental data, the model validity is verified and the TEMSM detector shows a superiority of a 113% photocurrent increase of 25.4 nA and similar low dark current of 3.16 pA at 30 V bias over the CEMSM device. Furthermore, the electrode angle α, width W and spacing S are optimized to obtain the enhanced device features including high UV−to-visible rejection ratio and large responsivity, etc. Under 30 V bias, the maximum UV-to-visible rejection ratio, comparable responsivity and external quantum efficiency at 310 nm are 13049, 0.1712 A/W and 68.48% for a TEMSM detector with device parameters of α=60°, W=3 μm and S=4 μm, respectively.
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Approach of Complex Networks for the Determination of Brain Death
SUN Wei-Gang, , CAO Jian-Ting, WANG Ru-Bin**
Chin. Phys. Lett. 2011, 28 (6):
068701
.
DOI: 10.1088/0256-307X/28/6/068701
In clinical practice, brain death is the irreversible end of all brain activity. Compared to current statistical methods for the determination of brain death, we focus on the approach of complex networks for real-world electroencephalography in its determination. Brain functional networks constructed by correlation analysis are derived, and statistical network quantities used for distinguishing the patients in coma or brain death state, such as average strength, clustering coefficient and average path length, are calculated. Numerical results show that the values of network quantities of patients in coma state are larger than those of patients in brain death state. Our findings might provide valuable insights on the determination of brain death.
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Optimal Attack Strategy in Random Scale-Free Networks Based on Incomplete Information
LI Jun, WU Jun**, LI Yong, DENG Hong-Zhong, TAN Yue-Jin**
Chin. Phys. Lett. 2011, 28 (6):
068902
.
DOI: 10.1088/0256-307X/28/6/068902
We introduce an attack model based on incomplete information, which means that we can obtain the information from partial nodes. We investigate the optimal attack strategy in random scale-free networks both analytically and numerically. We show that the attack strategy can affect the attack effect remarkably and the OAS can achieve better attack effect than other typical attack strategies. It is found that when the attack intensity is small, the attacker should attack more nodes in the "white area" in which we can obtain attack information; when the attack intensity is greater, the attacker should attack more nodes in the "black area" in which we can not obtain attack information. Moreover, we show that there is an inflection point in the curve of optimal attack proportion. For a given magnitude of attack information, the optimal attack proportion decreases with the attack intensity before the inflection point and then increases after the inflection point.
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97 articles
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