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With the combined use of the drift-diffusion (DD) model, experimental measured parameters and small-signa1 sinusoidal steady-state analysis, we extract the Y -parameters for 4H-SiC buried-channel metal oxide semiconductor field effect transistors (BCMOSFETs). Output short-circuit current gain G and Mason's invariant U are calculated for extrapolating unity current gain frequency in the common-source configuration fT and the maximum frequency of oscillation fmax, respectively. Here fT = 800 MHz and fmax = 5 GHz are extracted for the 4H—SiC BCMOSFETs, while the field effect mobility reaches its peak value 87cm2/Vs when VGS = 4.5V. Simulation results clearly show that the characteristic frequency of 4H-SiC BCMOSFETs and field effect mobility are superior, due to the novel structure, compared with conventional MOSFETs.

Remarkable triaxiality is found in the high-K isomeric states of A ~ 130 nuclei using the configuration-constrained calculations of potential-energy surfaces. The triaxiality gives the further understanding of the decay properties of the isomers. The calculation with triaxiality can well explain the measured quadrupole moment of the Kπ = 7−isomer in 130Ce.

We present an efficient one-step scheme for a single spin measurement based on nuclear magnetic resonance (NMR) techniques. This scheme considerably reduces the time of operation using a spin star network where a target spin and an ancillary spin are coupled to a ring of N spins. As opposed to the proposal in [Phys. Rev. Lett. 97(2006) 100501] using a cubic lattice crystal to achieve a cubic speedup, the distinct advantage of this scheme is that under ideal conditions it requires the application of only one step to create a system of N correlated spins. In the process of single spin measurement, the total macroscopic magnetization, the individual magnetization and the transfer fidelity are calculated analytically as simple cosine functions of time and the amplitude of irradiation.

The ferroelectric crystal Ba2TiSi2O8 with high second-order optical nonlinearity is precipitated in Sm3+-doped BaO-TiO2-SiO2 glass by a focused 800nm, 250kHz and 150 fs femtosecond laser irradiation. No apparent blue and red emissions are observed at the beginning, while strong blue emission due to second harmonic generation and red emission due to the f-f transitions of Sm3+ are observed near the focal point of the laser beam after irradiation for 25s. Micro-Raman spectra confirm that Ba2TiSi2O8 crystalline dots and lines are formed after laser irradiation. The mechanism of the phenomenon is discussed.

In this paper we propose a new scheme of long-distance quantum cryptography based on spin networks with qubits stored in electron spins of quantum dots. By conditional Faraday rotation, single photon polarization measurement, and quantum state transfer, maximal-entangled Bell states for quantum cryptography between two long-distance parties are created. Meanwhile, efficient quantum state transfer over arbitrary distances is obtained in a spin chain by a proper choice of coupling strengths and using spin memory technique improved. We also analyse the security of the scheme against the cloning-based attack which can be also implemented in spin network and discover that this spin network cloning coincides with the optimal fidelity achieved by an eavesdropper for entanglement-based cryptography.

The micro-void growth by dislocation emission under tensile loading is explored with focus on the influence of crystal orientations. Based on the elastic theory, a dislocation emission criterion is formulated. It is predicted that the preferential location of dislocation nucleation and its threshold stress are dependent on the crystal orientation. Large-scale molecular dynamics (MD) simulations are also performed for single crystal copper to illustrate the dislocation evolution pattern associated with a nano-void growth. The results are in line with those given by the theoretical prediction. As revealed by MD simulations, the characteristics of void growth at micro-scale depend greatly on the crystal-orientation.

We investigate magnetic and crystalline microstructures of melt-spun (Fe0.675Pt0.325)(100-x)B-x (x = 12, 14, 16, 18, 20) nanocomposite ribbons after optimal thermal treatment using a magnetic force microscope. The magnetic microstructures are characterized by darker spots adjacent to brighter ones in a sub-micro scale and in random distribution. It is found that the strength of the exchange coupling interaction between the crystals in the 10-100nm scale, implied by the maximum value (delta M)(max) of the Henkel plot, could be roughly described by the ratio of the average width of the magnetic spots (w) over bar to the average crystal size (D) over bar for the ribbons. Moreover, we find that the intrinsic coercivity H-j(c) of the ribbons is sensitive to their crystal sizes, and the smaller (D) over bar, the higher jHc. Finally, by using roughness analysis, the curve of the root mean square values of the phase shift of the magnetic force images versus the boron content x is obtained, which is qualitatively consistent with that of the magnetization sigma(12)kOe of the ribbons versus x.

We propose an extension of quantum key distribution based on encoding the key into quNits, i.e. quantum states in an N-dimensional Hilbert space. In our protocol, we adopt asymmetric measurement scheme resulting in an efficiency higher than previous protocols and a generalized Bell inequality [Phys. Rev. Lett. 92 (2004) 130404] is employed to detect the presence of an eavesdropper Eve. We also derive the information gained by a potential eavesdropper Eve applying a cloning-based attack and the maximal error rate which measures the robustness of the protocol. The result shows that the security of our scheme increases with the dimension N.

Transverse trapping efficiency of optical tweezers is important in many force measurement applications. For improving the transverse trapping efficiency, we propose a simple scheme in which the Gaussian beam does not fully cover the aperture of the objective. Both experiment and theoretical simulation qualitatively demonstrate the scheme. It is expected that the results will be useful for the design of optical tweezers.

With an impact velocity varying from 196.9 m/s to 317.9 m/s and ratios of flyer/sample thickness of 2:4 and 3:6, the free-surface velocity profiles of the shock compressed high purity aluminium (HPA 99.999%) samples are measured with a velocity interferometer system for any reflector. Based on the vibrating features of the velocity profiles, the damage behaviour of HPA is analysed. The results indicate that the vibrating amplitude increases with increasing shock stress, and the subsequent reverberations describing the spall become more obvious. When the shock stress in the material is below a critical or smaller than the threshold level, the free-surface velocity profile replicates virtually the form of the compression pulse inside the sample. When the impact stress exceeds a critical value (1.4 GPa), the micro damage would appear, and the free-surface velocity profile changes significantly, showing a series of short-duration reverberations in the profile. When the impact stress exceeds the threshold of damage, a compressive disturbance called the ``spall pulse'' appears in the free-surface velocity profile, and the subsequent reverberation becomes regular again. The measured spall strength of HPA is much higher than those of commercially pure aluminium reported in many references. In addition, the strength of HPA is similar to that of single-crystal aluminium.

With the environment temperature varying from 273 K to 773 K, the dynamic process of void growth in pure aluminium at high strain-rate loading is calculated based on the dynamic growth equation of a void with internal pressure. The result shows that the effect of temperature on the growth of void should be emphasized. Because the initial pressure of void with gas will increase and the viscosity of materials will decrease with the rising of temperature, the growth of void is accelerated. Furthermore, material inertia restrains the growth of void evidently when the diameter exceeds 10 μm. The effect of surface tension is very weak in the whole process of void growth.

The structural transition of bulk and nano-size Gd2O3:Eu are studied by high pressure energy disperse x-ray diffraction (XRD) and high pressure photoluminescence. Our results show that in spite of different size of Gd2O3 particles, the cubic structure turns into a possible hexagonal one above 13.4 GPa. When the pressure is released, the sample reverses to the monoclinic structure. No cubic structure presents in the released samples. That is to say, the compression and relaxation of the sample leads to the cubic Gd2O3:Eu then turns into the monoclinic one.

Al2O3 thin films are grown by atomic layer deposition on GaAs substrates at 300°C. The structural properties of the Al2O3 thin film and the Al2O3/GaAs interface are characterized using x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and x-ray photoelectron spectroscopy (XPS). The XRD results show that the as-deposited Al2O3 film is amorphous. For 30 atomic layer deposition growth cycles, the thicknesses of the Al2O3 thin film and the interface layer from the HRTEM are 3.3 nm and 0.5 nm, respectively. XPS analyses reveal that the Al2O3/GaAs interface is almost free from As2O3.

We design a pulsed power source based on the technique for explosive-driven demagnetization. The physical process and geometry structure of this power source are described in detail and several formulae are deduced to predict some important properties of the power source. With a Φ 40 mm×20 mm×10 mm cylindrical magnet, the maximum output voltage and current reaches 125.5 V and 862.9 A, respectively. The rise time of the front edge of the output voltage is about 264 ns. On the 0.05 Ω simulative load, the net power is 37 kW.

Failure wave generations on both impacted surface and internal surface inside the sample have been observed for K9 glass under planar shock wave loading, which demonstrates that formation of failure wave is a process related to the surface microcracks nuclei developing. Based on these observations, a hypothesis is suggested that the large local strains resulting from the rearrangement of SiO4 tetrahedral within the permanent densification region behind the shock wave front and then strains releasing due to the surface microcracks developing could be responsible for the failure wave generation.

A novel dmit2− salt: (tetramethylammonium)bis(1,3-dithiole-2-thione-4,5-dithiolato) copper, abbreviated as MECu, is synthesized and its third-order optical nonlinearity is characterized by Z-scan technique at a wavelength of 1064 nm with laser duration of 30 ps. Z-scan curves reveal a negative Kerr coefficient at 1064 nm and no nonlinear absorption is observed. The nonlinear refraction coefficient n2 and the second hyperpolarizability γ have been determined to be as large as 2.15×10−11 esu and 3.23×10−31 esu, respectively, suggesting MECu is a potential material for optical device applications.

In this paper, a controlled laboratory experiment to investigate the response properties of reflectometry to the density fluctuations is presented. The reflectometer signal is observed to be highly spatially localized in the plasma. The quantitative measurement has demonstrated that the signal originates about one free space wavelength of the probe wave in front of the critical layer and this position is independent of the fluctuation wavenumber. It is also found that the sensitivity of transverse response to wavenumbers is different from that of longitudinal response.

We investigate the photorefractive phase conjugation in a Ce:Fe:LiNbO3 crystal as a function of temperature (293-393 K) and find the phase conjugate reflectivity increases sharply in the vicinity of 55, 70 and 110° C. The anomalous phenomenon is possibly concerned with the structural phase transformation of a crystal, which induces an extra internal electric field to influence the phase conjugation. The value of the field is estimated at the order of 105 V/m, in agreement with the published data.

We present a method of measuring the parameters of a photorefractive crystal in codirectional two-wave mixing that is suitable for two-wave mixing in the intermediate stage (before saturation). Three parameters of a crystal, the exponential gain coefficient, saturation intensity and intensity absorption coefficient, can be measured simultaneously by using this method. The three parameters of a Ce:KNSBN are measured and the measured data are checked by another independent measurement.

Graphite doped MgB2−xCx (x = 0.00, 0.05, 0.10) wires were fabricated via the in situ powder-in-tube method in flowing argon by using low carbon steel tubes as the sheath materials. With the increase of graphite concentration, the amount of unreacted graphite in the core area increases, and the average grain size of MgB2 decreases. It is found that the critical current density Jc can be significantly improved by graphite doping. The MgB2 wire with x = 0.05 exhibits the best Jc value of 16710 A/cm2 at 6 K, 4.5 T, but the MgB1.9C0.1 wire has the highest Jc value of 2060 A/cm2 at 6 K, 8 T. It is suggested that the enhancement of Jc is due to not only the improvement of the microstructure features but also the introduction of pinning centres.

ZnO thin films were successfully deposited on Si (100) substrates by chemical vapour deposition (CVD) at atmospheric pressure (1 atm). The only solid source used here is zinc acetate, (CH3COO)2Zn, and the carrier gas is nitrogen. The sample, which was prepared at 550 degrees C during growth and then annealed in air at 900 degrees C, has only a ZnO (002) diffraction peak at 34.6 degrees with its FWHM of 0.23 degrees in the XRD pattern. The room-temperature PL spectrum shows a strong ultraviolet emission with the peak centred at 380 nm. We analysed the effects of many factors, such as the source, substrates, growth and annealing temperatures, and annealing ambience, on the structural and optical properties of our prepared ZnO films.

High-performance thin-film transistors (TFTs) with a low thermal budget are highly desired for flexible electronic applications. In this work, the TFTs with atomic layer deposited ZnO-channel/Al2O3-dielectric are fabricated under the maximum process temperature of 200°C. First, we investigate the effect of post-annealing environment such as N2, H2-N2 (4%) and O2 on the device performance, revealing that O2 annealing can greatly enhance the device performance. Further, we compare the influences of annealing temperature and time on the device performance. It is found that long annealing at 200°C is equivalent to and even outperforms short annealing at 300°C. Excellent electrical characteristics of the TFTs are demonstrated after O2 annealing at 200°C for 35 min, including a low off-current of 2.3 × 10−13 A, a small sub-threshold swing of 245 mV/dec, a large on/off current ratio of 7.6×108, and a high electron effective mobility of 22.1 cm2/Vs. Under negative gate bias stress at − 10 V, the above devices show better electrical stabilities than those post-annealed at 300°C. Thus the fabricated high-performance ZnO TFT with a low thermal budget is very promising for flexible electronic applications.

The effect of higher dimensional quark-gluon condensates on the effective quark-antiquark potential is investigated. In this scenario, c (c) over bar and b (b) over bar spectra are studied. It is shown that the vacuum condensates of the d = 5 and d = 6 operators, where d denotes the dimension of the operator, still cause notable effects. The perturbative loop contributions from the s-channel scattering and t-channel annihilation processes to the potential are almost the same. These contributions are opposite in sign to the non-perturbative contributions of the d = 4 operator condensates.

Amorphous FexCu1-x thin films with x ranging from 0.21 to 0.81 have been obtained by rf-magnetron sputtering. The structure and the electric transport properties of the films can be controlled by both the composition and annealing temperature. The resistances of the films decrease with the temperature increasing from 12 to 300 K, which is the typical semiconductor characteristic. After annealing at 400° C for 5h, the amorphous FexCu1-x thin film is crystallized and exhibits electric transport property an normal metal film. The dependence of resistance-temperature characteristics of the films on the composition and deposition time is described.

The intensity response of an optically erased photorefractive two-wave mixing to the erase beam is studied by using the coupling wave equation and the band-transport model. The concepts of response strength and the minimum response intensity are introduced and their temperature dependence is investigated. A 2-fold increase in the response strength and 4-fold decrease in minimum response intensity have been experimentally observed in Ce:KNSBN at 633 nm when the crystal temperature is raised from 320 to 370 K. These experimental results are in agreement with theoretical analysis and show that the response property can be improved by changing the crystal temperature.

A new Ag rough film system, deposited on silicone oil surfaces by rf-magnetron sputtering method, has been fabricated. The chrysanthemum-like surface morphology at micron length scale is observed. It is proposed that the anomalous critical behavior mainly results from the relative shift between the Ag atom clusters and the substrate. The discussion of the deposition mechanism is also presented.

We present the experimental and numerical results of two-dimensional x-ray imaging due to fast electron transport in a solid target. A 40-μm-thick copper film target is irradiated by a 100 mJ, 50 fs normal incident laser pulse. The full width at half maximum of the x-ray photon dose is 25 μm, and the divergence angle of fast electrons is 25°–30°, which is detected by the pin-hole x-ray imaging technique. The target surface plasma layer is compressed by a ponderomotive force into a depth of 0.2λ. The plasma wave accompanied by fast electrons transporting into the target is studied by dividing the plasma into layers in a radial direction. A narrow fast electron channel, which is approximately 8 μm–10 μm in width, mainly contributes to the x-ray dose.

We focus on the investigation of the spatial distribution and temporal evolution of N2 (A3Σu+, ν = 0) in a very early afterglow of a pulsed dc nitrogen discharge. The results indicate that a fast quenching process of N2 (A3Σu+, ν = 0) exists in the very early afterglow. We study the dependence of this fast quenching process on the discharge pressure 20–40 torr. It seems that this fast quenching behavior of N2 (A3Σu+, ν = 0) found in our experiment can be ascribed to the combined action of pooling reaction and collisions with N atoms through N2 (A3Σu+)+N2 (A3Σu+) → N*2+N2(N*2=N2(B3Πg, C3Πu, C'3Πu, C''5Πu)) and N2(A3Σu+)+N(4S)→N(2P)+N2, respectively. Meanwhile, the decay studies of N2(A3Σu+, ν = 0) near the anode and cathode infer that the production of N(4S) atoms does not distribute uniformly along the axis of the discharge gap at relatively low pressure, and this effect becomes gradually inconspicuous with the increasing discharge pressure.