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In this paper, we derived an exact solution of the spherically symmetric Hayward black hole surrounded by perfect fluid dark matter (PFDM). By applying the Newman–Janis algorithm, we generalized it to the corresponding rotating black hole. Then, we studied the shadows of rotating Hayward black hole in PFDM. The apparent shape of the shadow depends upon the black hole spin [Formula: see text], the magnetic charge [Formula: see text] and the PFDM intensity parameter [Formula: see text]. The shadow is a perfect circle in the non-rotating case [Formula: see text] and a deformed one in the rotating case [Formula: see text]. For a fixed value of [Formula: see text], the size of the shadow increases with the increasing [Formula: see text], but decreases with the increasing [Formula: see text]. We further investigated the black hole emission rate. We found that the emission rate decreases with the increasing [Formula: see text] (or [Formula: see text]) and the peak of the emission shifts to lower frequency. Finally, we discussed the observational prospects corresponding to the supermassive black hole Sgr A[Formula: see text] at the center of the Milky Way.

The quantitative method of iodine monoxide radical (IO) using incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) in the 435–465 nm band is described in this paper. In order to obtain the concentration of IO accurately, the parameters such as the mirror reflectivity, effective cavity length and sample loss of the IBBCEAS system are evaluated. Using the difference of Rayleigh scattering between nitrogen and helium, the reflectivity curve of the high-reflection mirror is obtained. The reflectivity R of the mirror at 436.1 nm of the IO absorption peak is about 0.99982, and the effective absorption optical path reaches 3.83 km under vacuum condition. According to the absorption of O4, the effective cavity length of the modified system is 60.7 cm. The Allan deviation is used to evaluate the performance of the system, and the standard deviation is used to analyze the detection sensitivity of the system. When the time resolution is 60 s, the detection sensitivity (2σ) of the system for IO and NO2 are 1.9 pptv and 20 pptv (part per trillion by volume), respectively. The iodine dissolved in potassium iodide (KI) solution is taken out by the bubbling method and react with ozone after photolysis to produce a stable concentration of IO sample gas. The IO loss in the sampling tube is calibrated, and the results show that the sampling tube has no significant effect on the IO loss. The IBBCEAS system is used to determine the linearity of IO, and the correlation coefficient R2 between the measured concentration of IO and the proportioned concentration in a concentration range from 39 to 530 pptv is 0.99. The IO produced by the reaction of iodine released from kelp with ozone is measured.

The second-generation high-temperature superconductor (2G HTS) is a good candidate for high field magnet due to its high critical temperature Tc,high critical current density Jc,and high irreversibility field Hirr.This paper presents the design and development of a 4.08 T (46 K) coil made of homemade 2G HTS.In order to meet the design requirement of HTS coil,the electromagnetic finite element modeling and optimization are carried out on the basis of the research of the properties of YBa2Cu3O7-x(YBCO) tapes.And the design scheme of HTS coil is completed.Then the HTS coil with an inner diameter of 100 mm is successfully constructed according to the scheme.It consists of a stack of 10 double-pancakes with the same outer diameter wound with YBCO tapes.The diameter and height of the HTS coil are 236 and 359 mm,respectively.A total of 1600 meters of YBCO tape are used to wind this HTS coil.We measure the I-V curves of superconducting coil at different cryogenic temperatures.First,liquid nitrogen is used to cool the HTS coil to 77 K,and then the temperature is reduced to 65 K by the decompression cooling method.The cooling coil containing liquid helium is used to exchange heat and cool the solid nitrogen to obtain much lower cryogenic temperature.The maximum operating currents of the HTS magnet at 77,65,and 55 K are 65,147,and 257 A,respectively,corresponding to the center magnetic field of 0.78,1.77,and 3.1 T.At 46 K,the HTS coil with an inner diameter of 100 mm generates a 4.08 T field at the center.And the magnetic field of superconducting coil is basically uniform in the medium plane.The results demonstrate a strong potential of home-made YBCO magnet for direct current high-field applications.

Ge is an indirect bandgap semiconductor, which can be converted into a direct bandgap semiconductor by using the modification techniques. The carrier radiation recombination efficiency of modified Ge is high, which can be used in optical devices. The mobility of Ge semiconductor carriers is higher than that of Si semiconductor carriers, so Ge device can work fast and have good frequency characteristics in electronic device. In view of the application advantages of modified Ge semiconductors in both optical devices and electrical devices, it has been a potential material of monolithic optoelectronic integration. The Ge and GeSn as optoelectronic device materials have a great competitive advantage, but there is no mature Ge-based monolithic photoelectric integration. In order to realize Ge-based optical interconnection, the bandgap of luminous tube, detector and waveguide active layer material must satisfy the following sequence:Eg,waveguide Eg,luminoustube Eg,detector. Therefore, in order to achieve the same layer monolithic photoelectric integration, we must modulate the energy band structure of the active layer material of the device. Unfortunately, the literature in this area is lacking. The band structure is one of the theoretical foundations for the monolithic photoelectric integration of the modified Ge materials, but the work in this area is still inadequate. In this paper, this problem is investigated from three aspects. 1) Based on the generalized Hooke's law and the principle of deformation potential, a modified Ge bandgap type transformation model is established under different modification conditions, perfecting the theory of converting the indirect switching into direct band gap of Ge. 2) On the basis of establishing the strain tensor and deformation potential model, a modified Ge band E-k model is established, and the relevant conclusions can provide key parameters for LED and laser device simulation models. 3) Based on the theory of solid energy band, the bandgap width modulation scheme of the modified Ge under the uniaxial stress is proposed, which provides an important theoretical reference for realizing the Ge-based single-layer photoelectric integration. The results in this paper can provide an important theoretical basis for understanding the material physics of the modified Ge and designing the active layers of the light emitting devices in the Ge based optical interconnection.

A supercell of a nanotube heterojunction formed by an (8, 0) carbon nanotube (CNT) and an (8, 0) silicon carbide nanotube (SiCNT) is established, in which 96 C atoms and 32 Si atoms are included. The geometry optimization and the electronic property of the heterojunction are implemented through the first-principles calculation based on the density functional theory (DFT). The results indicate that the structural rearrangement takes place mainly on the interface and the energy gap of the heterojunction is 0.31 eV, which is narrower than those of the isolated CNT and the isolated SiCNT. By using the average bond energy method, the valence band offset and the conduction band offset are obtained as 0.71 and −0.03 eV, respectively.

The feature of conduction band (CB) of Tensile-Strained Si(TS-Si) on a relaxed Si1-xGex substrate is systematically investigated, including the number of equivalent CB edge energy extrema, CB energy minima, the position of the extremal point, and effective mass. Based on an analysis of symmetry under strain, the number of equivalent CB edge energy extrema is presented; Using the KP method with the help of perturbation theory, dispersion relation near minima of CB bottom energy, derived from the linear deformation potential theory, is determined, from which the parameters, namely, the position of the extremal point, and the longitudinal and transverse masses (m*1 and m*t) are obtained.

The carrier microscopic transport process of uniaxial strained Si n-channel metal-oxide-semiconductor field-effect transistor (NMOSFET) is analyzed under -ray radiation. The model of radiation-induced defect densities that are quantitative representations of trapped charges integrated across the thickness of the oxide (Not), and the number of interface traps at the semiconductor/oxide interface (Nit), is established. The variations of electrical characteristics of the uniaxial strained Si nanometer NMOSFET are also investigated under the total dose radiation. The device of uniaxial strained Si nanometer NMOSTET is irradiated by a 60Co -ray laboratory source at a constant dose rate of 0.5 Gy (Si)/s. The TID is deposited in several steps up to a maximum value of 2.5 kGy. Electrical measurements are performed at each TID step. All irradiated samples are measured using field test, and are required to finish measurement within 30 min, in order to reduce the annealing effect. Static drain-current ID vs. gate-voltage VGS electrical characteristics are measured with an HP4155B parametric analyzer. Some parameter extractions presented here come from these static measurements including the threshold voltage VTH, the trans-conductance gm, and the leakage current IOFF (ID at VGS=0 V and VDS=VDD). Irradiation bias:VG=+1 V, drain voltage VD is equal to source voltage VS (VD=VS=0). Measurement bias:VG=0-1 V, scanning voltage Vstep=0.05 V, VD=50 mV, and VS=0. The results indicate the drift of threshold voltage, the degradation of carrier mobility and the increase of leakage current because of the total dose radiation. Based on quantum mechanics, an analytical model of tunneling gate current of the uniaxial strained Si nanometer is developed due to the total dose irradiation effect. Based on this model, numerical simulation is carried out by Matlab. The influences of total dose, geometry and physics parameters on tunneling gate current are simulated. The simulation results show that when radiation dose and bias are constant, the tunneling gate current increases as the channel length decreases. When the structure parameters and the stress are fixed, the tunneling gate current increases with the increase of radiation dose. Whereas at a given the radiation dose, tunneling gate current will decrease due to the stress. When radiation dose and bias are kept unchanged, the tunneling gate current increases with the thickness of the gate oxide layer decresing. When the gate-source voltage, the thickness of oxide layer and stress are fixed, tunneling gate current is reduced with the increase of doping concentration in channel. When the structural parameters, the gate-source voltage and radiation dose are constant, the tunneling gate current decreases with increasing drain-source voltage. In addition, to evaluate the validity of the model, the simulation results are compared with experimental data, and good agreement is confirmed. Thus, the experimental results and proposed model provide good reference for research on irradiation reliability and application of strained integrated circuit of uniaxial strained Si nanometer n-channel metal-oxide-semiconductor field-effect transistor.

As a positionsensitive detector, laser quadrant photodetector(QPD) is widely used in the areas such as laser guidance, laser radar and space optical communication. In the echoed laser pulse detection mode, the laser pulse signal arrived at the QPD photosensitive surface is changed in pulse amplitude, pulse width and pulse waveform due to the influences of target characteristic, atmospheric transmission and other complex factors. In addition, there are random noises in QPD itself and the signal processing circuit. These factors will have an uncertainty effect on the angle measurement accuracy of the QPD. However, the study on the statistical distribution of digital angle measurement of pulsed laser QPD has not been carried out so far. To investigate this angle measurement statistical distribution, the channel of laser angle measurement circuit and the echoed laser spot on QPD photosensitive surface should be modeled first. A measurable signal model in one quadrant of QPD processing circuit channel is established based on the type of random noise and the type of desired ideal signal. The random noise model is considered to be a Gaussian distribution, and the ideal laser pulse signal is considered to have the Gaussian or inverted parabolic distribution in the time domain. Taking into account the QPD symmetry, the statistical distributions of angle measurement value αy for five different spot centers are calculated by the Monte Carlo simulation method within the range θ0∈[0,π/4], under the conditions of different signal distribution types in the time domain, different total peak powers of the spots, different ideal signal widths at half maximum, and different standard deviations of equivalent noise voltage probability density. Simulation results show that the statistical distribution of the measured angle αy value is a normal distribution, and is influenced by the above-mentioned conditions, especially by the signaltonoise ratio in one quadrant. QPD possesses higher angular accuracy as the spot center is closer to the axis center. While the spot center is not closer to the axis center, the mean of statistical distribution of the QPD measurement angle αy is always less than the ideal angle measurement value. Therefore, in order to improve the angle measurement accuracy of the pulsed laser QPD for digital purpose, laser pulse transmit power should be increased, or the noise of each circuit channel of QPD should be reduced, or the laser pulse width should be increased by modulating appropriately.

Micron grade boron-doped diamond crystals with octahedral morphology are successfully synthesized in a Fe—Ni—C—B system under high pressure and high temperature (HPHT). The effects of the additive boron on synthesis conditions, nucleation and growth, crystal morphology of diamond are studied. The synthesized micron grade diamond crystals were characterized by optical microscope (OM), scanning electron microscope (SEM), x-ray diffraction (XRD) and Raman spectroscopy. The research results show that the V-shaped section of synthetic diamond moves downwards to the utmost extent due to 0.3a wt% (a is a constant.) boron added in the synthesis system. The crystal colour is black, and the average crystal size is about 25 μm. The crystal faces of synthetic diamond are mainly {111} face. The synthesis of this kind of diamond is few reported, and it will have important and widely applications.

In YBa2Cu3O7-x (YBCO) film there exists thickness effect: the critical current density of YBCO film drops precipitously as the coating thickness increases, especially in the case that the thickness of YBCO film exceeds 1 m. In this paper, we introduce very thin layers of CeO2 into YBCO layers and successfully fabricate the structure of YBCO/YBCO/CeO2/YBCO superconducting thick film. Firstly, YBCO films with two layers are fabricated on a LaAlO3 substrate by a multiple coatings process using a trifluoroacetate metal organic deposition method. Secondly, CeO2 thin films are deposited on YBCO films by RF-sputtering. Finally, we prepare the third YBCO film on CeO2interlayer. No cracks are observed in scanning electron microscopy images of these films; further, the majority of the grains in the films are well-textured and c-axis oriented. The full-width-half-maximum of the out-of-plane texture is measured to be 1.395 for the multilayer YBCO film at a thickness of 2 m Using this multilayer technology, we achieve Jc values of up to 1.36 MA/cm2 (77 K, self-field) in films as thick as 2 m, for an extrapolated critical current of 272 A/cm. We attribute the enhanced performance of the thick YBCO film to the CeO2 interlayer which playsan important role in transmission texture and stress relaxation.

Laser proximity fuze is a kind of active detecting system which has been extensively equipped in both conventional and guided missile ammunitions. It uses a pulsed laser for detecting and ranging a target, accurately providing information about target angle and distance. The system emits a short pulse of laser beams which come into contact with the target and receives the light scattered back. After transducing light into electric signal, target range could be obtained with proper signal processing technique. The width and amplitude of the echo could vary if targets are of different characteristics, which leads to distributed target ranging results. Therefore, a better understanding of the relationship between target characteristic and ranging distribution can increase the precision of the pulsed laser proximity detecting system.In this paper, the emitted laser is modeled as a Gaussian pulse. The corresponding impulse response equation and echo equation of the pulsed laser for the planer target are derived. Considering the echo broadening effect, relative broadening ratio is determined from the echo equation. Then the relationships between the echo broadening coefficient and the parameters of tilt angle of planar target, laser divergence angle, and laser pulse width are analyzed. The results show that relative broadening ratio increases with the increase of the tilt angle of planar target or laser divergence angle, and decreases as the laser pulse width decreases. Based on the echo equation of pulsed laser and constant threshold leading edge detection, the probability density function of the planar target ranging is derived analytically. The influences of changing parameters of tilt angle of planar target, power of emitted laser, laser divergence angle, and threshold-to-noise ratio（TNR) on statistical ranging distribution are simulated.Monte Carlo simulation is performed for the whole waveform ranging experiment. The pulsed laser ranging platform is built and 20 m ranging experiment is conducted. The result shows that the ranging probability density distribution from Monte Carlo simulation is close to that from the experiment. As the tilting angle of target increases, ranging mean and variance both increase. When the tilting angles are 0, 20, 40 or 60, the signal-to-noise ratio（SNR) is larger than the TNR, and the ranging distribution is Gaussian. When the tilting angle is 70, the SNR is smaller than the TNR, and the ranging distribution is distorted with a longer rising edge and a shorter falling edge from the original Gaussian profile. This study could provide theoretical basis for the research of the ranging distribution of pulsed laser detector with the consideration of target characteristic.

A 6-boson system has been qualitatively studied based on symmetry consideration. Emphasis is placed on the ground rotation band based on the octahedron structure. In this band the L = 1, 2, and 3 states are found to be prohibited by symmetry. Therefore there is a gap to hinder the rotational excitation of the ground state.

A complete set of quantum numbers for the eigenstates of the Na3+ system has been introduced. The structure of the ground rotation band has been deduced based on symmetry considerations. This band is found to be different from that of H3+, though they are similar in dynamics.

The evolution of two-component cold atoms on a ring with spin–orbit coupling has been studied analytically for the case with N noninteracting particles. Then, the effect of interaction is evaluated numerically via a two-body system. Two cases are considered: (i) Starting from a ground state the evolution is induced by a sudden change of the laser field, and (ii) the evolution starting from a superposition state. Oscillating persistent spin-currents have been found. A set of formulae have been derived to describe the period and amplitude of the oscillation. Based on these formulae the oscillation can be well controlled via adjusting the parameters of the laser beams. In particular, it is predicted that movable stripes might emerge on the ring.

The capacitance model is fundamental for the transient analysis, AC analysis and noise analysis of uniaxially strained Si MOSFET device and circuit. Firstly, the 16-differential capacitance model for uniaxially strained Si NMOSFET is developed. Secondly, the simulation results from that model match the experimental results well, which validates the accuracy of the model. Meanwhile the simulated relations of key gate capacitance Cgg to stress intensity, bias voltage，channel length and concentration of poly gate are obtained and analyzed, showing that the value of Cgg is a little larger than that of strainless bulk device while the changing tendency keeps the same.

Performance of a nano-scale MOS (metal-oxide-semiconductor) can be significantly improved by uniaxial stress, caused by the SiN film deposited on the surface of MOS. Although this technique has been widely used in the performance improvement of CMOS and integrated circuit, the physical mechanism for instance, how is the strain in MOS channel caused by the SiN film? how about the relation between the kinds of the structure of SiN film needed to be discussed in depth. On the basis of the ISE TCAD, three typical models for stress analysis——such as the segmentation structure model, the closed-loop structure model and the integrity structure model——are proposed. And then, this paper reveals the physical mechanism about how the stress in MOS channel is caused by the SiN film and how much the magnitude of the stress in MOS channel is induced. Results shows that: 1) The “step” structure is the necessary condition for the strain in the MOS channel to be caused by the SiN film. 2) With the tendency for SiN film to shrink or expand, the film may lead to the deformation along the MOS source/drain region of the Si material, which causes the deformation of Si in the channel. 3) The whole of the channel stress in SiN film is equal to the sum of the stress in the source/drain imposed by the SiN film above the source/drain, the stress which the “closed loop structure” applies to the channel, and the stress generated in the channel by the whole SiN film. Our conclusions may provide the valuable references to the manufacture of nano-scaled MOS and the research of the novel inducing stress technique.

We study the propulsion matrix of bacterial flagella numerically using slender body theory and the regularized Stokeslet method in a biologically relevant parameter regime. All three independent elements of the matrix are measured by computing propulsive force and torque generated by a rotating flagellum, and the drag force on a translating flagellum. Numerical results are compared with the predictions of resistive force theory, which is often used to interpret micro-organism propulsion. Neglecting hydrodynamic interactions between different parts of a flagellum in resistive force theory leads to both qualitative and quantitative discrepancies between the theoretical prediction of resistive force theory and the numerical results. We improve the original theory by empirically incorporating the effects of hydrodynamic interactions and propose new expressions for propulsive matrix elements that are accurate over the parameter regime explored.

Based on the structure of strained Si/SiGe NMOSFET, a unified charge model is presented, in which charge conservation is guaranteed by using the charge as the state variable. The model describes device characteristics from subthreshold to strong inversion as well as from the linear to the saturation operating regions using a smoothing function, and guarantees the continuities of charges and capacitances. Furthermore, capacitance models have been presented using Verilog-A, a language to describe analog behavior. Comparisons between the model and measured data show that the charge model can describe the device characteristics well. The proposed model is useful for the design and simulation of integrated circuits made of strained Si.

Hot carrier gate current is one of the factors that influence the power and reliability of metal-oxide-semiconductor field effect transistor (MOSFET). Based on the physical process of generation of the hot carrier effect, a model of hot carrier gate current for uniaxially strained Si NMOSFET is developed. With that model, the simulation results of hot carrier gate current against stress intensity, gate-source bias, channel doping concentration, and drain-source bias are obtained and analyzed. The relationship between life time of time-dependent dielectric break down (TDDB) and gate-source bias is simulated and analyzed. Results show that the uniaxially strained Si MOSFET not only has smaller hot carrier gate current, but also has more stable reliability as compared with the strainless bulk device. Meanwhile, the simulation results match the experimental results very well, which validates the accuracy of the model.

In this work, the carrier microscopic transport process of biaxial strained Si p-channel metal-oxide-semiconductor field-effect transistor (PMOSFET) under γ -ray radiation has been studied. Effect of γ-ray on devices and the relationship between the variation of device electrical characteristics and the total dose are investigated. A model for considering the degradation of threshold voltage and transconductance due to the total dose radiation is established. Based on this model, numerical simulation has been carried out. Results show that the threshold voltage of PMOSFET decreases with increasing radiation dose. At a lower total dose, the threshold voltage decreases linearly. However, at a higher total dose, it becomes saturated. The degradation can be explained by the generation of trapped charges which increase the impact possibility of carriers in the channel and induce the reduction of mobility and transconductance accordingly. Finally, the simulation results are compared with the experimental data. A good agreement is observed, indicating the validation of our proposed model.

Indirect bandgap Ge can be turned to a direct bandgap semiconductor by the alloy-modified technique, which can be applied to advanced photonic devices and electronic devices. Based on 8 bands Kronig-Penny Hamilton, this paper focuses on the physical parameters of direct bandgap Ge1-xSnx, such as conduction band effective density of states, valence band effective density of states and the intrinsic carrier concentration, and aims to provide valuable references for understanding the direct bandgap modified Ge materials and device physics as well as their applications. Results show that: conduction band effective density of states in direct bandgap Ge1-xSnx alloy decreases obviously with increasing Sn fraction, while its valence band effective density of states almost does not change with increasing Sn fraction. Compared with bulk Ge, the conduction band effective density of states and valence band effective density of states in direct bandgap Ge1-xSnx alloy are lower by two and one orders of magnitude respectively; the intrinsic carrier concentration in direct bandgap Ge1-xSnx alloy increases with increasing Sn fraction, and its value is an order of magnitude higher than that of bulk Ge.

The tunneling field-effect transistor (TFET) is a potential candidate for the post-CMOS era. In this paper, a threshold voltage model is developed for this new kind of device. First, two-dimensional (2D) models are used to describe the distributions of potential and electric field in the channel and two depletion regions. Then based on the physical definition of threshold voltage for the nanoscale TFET, the threshold voltage model is developed. The accuracy of the proposed model is verified by comparing the calculated results with the 2D device simulation data. It has been demonstrated that the effects of varying the device parameters can easily be investigated using the model presented in this paper. This threshold voltage model provides a valuable reference to TFET device design, simulation, and fabrication.

A comprehensive analysis is made on the performance of decoy-state quantum key distribution with a heralded pair coherent state photon source from the effectiveness, stability and feasibility. The key generation rate, quantum bit error rate, and optimal signal intensity each as a function of secure transmission distance are simulated and analyzed by the three-intensity decoy-state method based on a heralded pair coherent state photon source with four groups of experimental data. Considering the intensity fluctuation, the stability of this method is simulated and discussed. Furthermore, the feasibility of the simple and easy method that is proposed with a heralded pair coherent state photon source is analyzed. The simulation results show that the key generation rate and secure transmission distance obtained from the decoy-state method with a heralded pair coherent state photon source are better than those obtained from the methods with a weak coherent state source and heralded single photon source. With the same intensity fluctuation, the heralded pair coherent state photon source is less stable than the heralded single photon source, but more robust than the weak coherent state source. However, the advantage in the effectiveness of the heralded single photon source can give rise to the shortage of the stability. Moreover, the two same modes of the heralded single photon source provide the feasibility to design a simple and easy passive decoy-state method.

Based on the structure of strained Si/SiGe NMOSFET, a unified drain current model is presented in this paper. The model describes current characteristics from subthreshold to strong inversion as well as from the linear to the saturation operating regions with a smoothing function, and guarantees the continuities of the drain current and its derivatives.Furthermore, the model accuracy is enhanced by including carrier velocity saturation and channel length modulation effects. Comparisons between the model and the measured data show that the drain current model can describe the device characteristics well. The proposed model is useful for the design and simulation of digital and analogy circuits made of strained Si.

Based on surrounding-gate schottky barrier metal-oxide semiconductor field transistor (MOSFET) structure, the distribution of surface potential is obtained by solving two-dimensional Poisson equation in cylindrical coordinates, and the threshold voltage model of surrounding-gate schottky barrier NMOSFET which is applicable to the low voltage of drain is built. According to the calculation results, the dependences of threshold voltage and drain-induced barrier-lowering on voltage of drain, channel radius and channel length are studied in detail, which can provide some reference for the design of surrounding-gate schottky barrier MOSFET device and circuit.

A new strained Si MOSFET structure with hetero-polycrystalline SiGe gate was studied, which combines the advantages of “gate engineering” and “strain engineering”. The new structure improved the carrier transport efficiency, suppressed the short-channel effects (SCE), and enhanced the performance on the basis of strain. Then a physically modeling strategy such as quasi-2D surface potential of strong inversion, threshold voltage, and channel current was presented for the strained Si NMOSFET. Finally, the above model was computed and the results were analyzed.

The development of strained-Si physical compact threshold voltage model is based on Poisson's equation, using the gradual channel approximation (GCA) and coherent quasi-two-dimensional (2D) analysis, as well as taking into account the effects of short channel effect (SCE), narrow channel effect (NCE), non-uniform doping effect, and drain-induced barrier lowering (DIBL) effect. Moreover, the threshold voltage parameters are extracted from the experimental results by software. Finally, the validity of our model is derived from the comparison of our simulation results. The proposed model may be useful for the design and simulation of very large scale integrated circuits (VLSI) made of strained-Si.

The gate capacitance-voltage (C-V) characteristic of strained SiGe pMOSFET is very different from that of bulk Si pMOSFET, and can be strongly affected by the channel doping. In this paper, we first study the formation mechanism of the "plateau" which can be observed in the gate C-V characteristics of strained SiGe pMOSFET, and then present a physics based analytical model to predict the gate C-V characteristic of strained SiGe pMOSFET. It is found that this plateau is channel doping dependent. The results from the model are compared with the experimental results and they are found to be in excellent agreement with each other, giving the evidence for its validity.

Accumulation MOS capacitor is more linear than inversion MOS capacitor and is almost independent of the operation frequency. In this paper, we present first the formation mechanism of the plateau, observed in the C-V characteristic of the strained-Si NMOS capacitor, and then a physical model for strained-Si NMOS capacitor in accumulation region. The results from the model show to be in excellent agreement with the experimental data. The proposed model can provide valuable reference for the strained-Si device design, and is has been implemented in the software for extracting the parameter of strained-Si MOSFET.

In this paper, the dispersion relationship is derived by using the k ? p method with the help of the perturbation theory, and we obtain the analytical expression in connection with the deformation potential. The calculation of the valence band of the biaxial strained Ge/(001)Si1?xGex is then performed. The results show that the first valence band edge moves up as Ge fraction x decreases, while the second valence band edge moves down. The band structures in the strained Ge/ (001)Si0.4Ge0.6 exhibit significant changes with x decreasing in the relaxed Ge along the [0, 0, k] and the [k, 0, 0] directions. Furthermore, we employ a pseudo-potential total energy package (CASTEP) approach to calculate the band structure with the Ge fraction ranging from x = 0.6 to 1. Our analytical results of the splitting energy accord with the CASTEP-extracted results. The quantitative results obtained in this work can provide some theoretical references to the understanding of the strained Ge materials and the conduction channel design related to stress and orientation in the strained Ge pMOSFET.

Based on the kp theory, the valence-band dispersion model for biaxial strained Ge/Si1-xGex is derived by taking strained Hamiltonian perturbation into account. The model can be used to calculate the valence band structure and hole effective mass along arbitrarily k wavevector direction in strained Ge grown on arbitrarily oriented relaxed Si1-xGex virtual substrate. The MATLAB simulation results of the model show that by comparison with relaxed Ge, the more anisotropy of the hole effective mass occurs in strained Si1-xGex and the hole effective mass of the top valence band decreases with the increase of Ge fraction. The results can supply valuable references to the conduction channel design related to stress and orientation in the Si-based strained Ge MOS devices and integrated circuits.

Based on Fermi's golden rule and the theory of Boltzmann collision term approximation, hole scattering mechanism in strained Si/(001)Si1-xGex, namely, tetragonal strained Si is studied, including ionized impurity, acoustic phonon, non-polar optical phonon and total scattering rates. It is found that the total scattering rate of hole in strained Si/(001)Si1-xGex decreases obviously with the increase of stress when Ge fraction (x) is less than 0.2 and the values continue to show a constant tendency. The total hole scattering rate of strained Si/(001)Si1-xGex decreases about 66% at most in comparison with one of unstrained Si. The hole mobility enhancement in strained Si material is due to the decrease of hole scattering rate. The result can provide valuable references for the research of hole mobility of strained Si materials and the design of PMOS devices.

Performance enhancement of strained Si material originates from the stress on it, which can be measured by Raman spectroscopy. A study of the theoretical model of strain-induced Raman spectrum frequency shift in strained Si material is of profound theoretical and practical significance. The Raman frequency shift of strained Si is significantly correlated with the stress intensity, the stress type and the crystal plane. However, the corresponding reports republished are lacking in integrality and systematization in the process of modeling. In this paper, according to the theory of Raman spectroscopy, based on Secular equation and Raman selection rules, quantitative relationships between strain tensor and Raman frequency shift for uniaxial and biaxial strained Si grown on (001), (101), and (111) SiGe substrates are achieved. On this basis, theoretical models of mechanical stress and Raman spectrum for uniaxial and biaxial strained Si materials grown on (001), (101), and (111) SiGe substrates are obtained using Hooke's law, respectively. The procedure for setling up these models is elaborate and systematic and the results obtained are comprehensive and quantificational, which can provide an important reference for the stress analysis in strained Si material.

A threshold voltage model is created by analyzing differents distributions of surface electric field and the condition of avalanche breakdown, based on the structure of a novel high speed semiconductor device p-IMOS in this paper. Model verification is carried out using the 2D device simulator ISE. By analyzing the model, the dependences of threshold voltage on drain-source voltage, Si layer thickness and gate length are studied. The results of the model are in good agreement with experimental results and ISE simulation results. The proposed model can also be easily used for the reasonable analysis and the design of p-IMOS.

In this paper, based on the framework of kp method, the influence of uniaxial stress on the conduction band energy-band structure of bulk-Si is analysed first, the coupling of 1 and 2 bands at the X point, and the influence of that band-band coupling on the minimum of energy valley are then separately discussed under the action of shear strain. On that basis, the dispersion relation close to the minimum is obtained. Furthermore, the different valley orientations need to be taken into account. Using the coordinate transformation, the modelling for dispersion relation of each valley with arbitrary uniaxial stress is finally achieved. The proposed analytical model in this paper is also suited to the understanding of the physical properties of uniaxial strained Si material and may provide some references for the study on bandstructure and electrical properties of the inversion layer in uniaxial strained Si nMOSFETs.

In this paper, the hole effective mass along arbitrarily k wavevector direction and the hole isotropic effective masses in strained Ge/(001)(101)(111)Si1-xGex are obtained with in the frame work of kp theory. It is found that the hole effective mass of the top valence band along [010] wave vector decreases obviously with stress increasing and its absolute value is smallest. The hole effective mass of the second valence band tends to gently decrease with stress increasing, and is not significant in magnitude. Compared with the existing isotropic effective quality, the result obtained in this paper is proved to be correct.

Under the control of the prepared initial state, two-body scattering of trapped neutral fermions is studied theoretically. Since the fermions collide inside the trap frequently, the effect of atom-atom interaction can be accumulated. On the momentum-representation, we find the presence of periodic probability density, which is much longer than that of bosons. The measurement and details of this periodic phenomenon might be valid information about weak interactions among neutral particles.

An analytical expression for the collector resistance of a novel vertical SiGe heterojunction bipolar transistor (HBT) on thin film silicon-on-insulator (SOI) is obtained with the substrate bias effects being considered. The resistance is found to decrease slowly and then quickly and to have kinks with the increase of the substrate—collector bias, which is quite different from that of a conventional bulk HBT. The model is consistent with the simulation result and the reported data and is useful to the frequency characteristic design of 0.13 μm millimeter-wave SiGe SOI BiCMOS devices.

Silicon germanium (SiGe) heterojunction bipolar transistor (HBT) on thin silicon-on-insulator (SOI) has recently been demonstrated and integrated into the latest SOI BiCMOS technology. The Early effect of the SOI SiGe HBT is analysed considering vertical and horizontal collector depletion, which is different from that of a bulk counterpart. A new compact formula of the Early voltage is presented and validated by an ISE TCAD simulation. The Early voltage shows a kink with the increase of the reverse base—collector bias. Large differences are observed between SOI devices and their bulk counterparts. The presented Early effect model can be employed for a fast evaluation of the Early voltage and is useful to the design, the simulation and the fabrication of high performance SOI SiGe devices and circuits.

The SiGe heterojunction bipolar transistor (HBT) on thin film SOI is successfully integrated with SOI CMOS by folded collector. This paper deals with the collector depletion charge and the capacitance of this structure. An optimized model is presented based on our previous research. The results show that the charge model is smoother, and that the capacitance model with considering different current flow areas, is vertical and horizontal depletion capacitances in series, showing that the depletion capacitance is smaller than that of a bulk HBT. The charge and capacitance vary with the increase of reverse collector-base bias. This collector depletion charge and capacitance model provides valuable reference to the SOI SiGe HBT electrical parameters design and simulation such as Early voltage and transit frequency in the latest 0.13 m SOI BiCMOS technology.

By solving Poisson equation, models of voltage and electric field distribution are build respectively in collector junction depletion layer of SiGe HBT (heterojunction bipolar transistor) with intrinsic SiGe layer. On this basis, models of the collector junction depletion layer width and delay time are obtained. Applying MATLAB, the impact of physical and electrical parameters on SiGe HBT collector junction depletion layer width and depletion delay time are quantitatively analyzed. When base doping concentration and collector junction reverse bias are large, the depletion delay time is quite long. But, when base doping external diffusion depth and collector region doping are large, the depletion delay time is quite short.

The strain tensor arising from uniaxial stress along an arbitrary direction on the (001) surface of Si is calculated. With these uniaxial strain tensor, the band structure of silicon material under arbitrary uniaxial stress on the (001) surface is calculated using K ·P perturbation theory coupled with linear deformation potential theory. The relation between energy band structure and stress parameters (type, direction, magnitude) was obtained. Finally, the uniaxial stress induced band structure change, such as that of the conduction band (CB) and the valence band (VB) edge levels, CB and VB splitting energy and the bandgap is demonstrated. Results of these band structure can be used as a guide for the design and the selection of the optimum strain and crystal orientation configuration of uniaxial strained silicon devices.

Based on strained silicon metal-oxide semiconductor field transistor (MOSFET) structure, the distribution of surface potential is obtained by solving two-dimensional Poisson equation, and the threshold voltage model is built. According to calculation results, the dependence of threshold voltage on germanium content of relaxed Si1－βGeβ, channel length, voltage of drain, doping content of substrate and channel are studied in detail, and the influence of drain-induced barrier-lowering on scaled strained silicon MOSFET is obtained, which can provide important reference for the design of strained silicon MOSFET device and circuit.

For scaled metal-oxide semiconductor field effect transistor (MOSFET) devices, normal operation is seriously affected by the static gate tunneling leakage current due to the ultra-thin gate oxide of MOSFET, and the novel MOSFET devices based on strained Si are similar to bulk Si devices in the effects. To illustrate the impact of gate leakage current on performance of novel strained Si device, a theoretical gate tunneling current predicting model by integral approach following the analysis of quasi-two-dimensional surface potential is presented in this study. On the basis of theoretical model, performance of MOSFET device was quantitatively studied in detail using ISE simulator, including different gate voltages and gate oxide thickness. The experiments show that simulation results agree well with theoretical analysis, and the theory and experimental data will contribute to future VLSI circuit design.

The base—collector depletion capacitance for vertical SiGe npn heterojunction bipolar transistors (HBTs) on silicon on insulator (SOI) is split into vertical and lateral parts. This paper proposes a novel analytical depletion capacitance model of this structure for the first time. A large discrepancy is predicted when the present model is compared with the conventional depletion model, and it is shown that the capacitance decreases with the increase of the reverse collector—base bias—and shows a kink as the reverse collector—base bias reaches the effective vertical punch-through voltage while the voltage differs with the collector doping concentrations, which is consistent with measurement results. The model can be employed for a fast evaluation of the depletion capacitance of an SOI SiGe HBT and has useful applications on the design and simulation of high performance SiGe circuits and devices.

A combined Ag nanoparticle with an insulating or conductive layer structure has been designed for molecular detection using surface enhanced Raman scattering microscopy. Optical absorption studies revealed localized surface plasmon resonance, which shows regular red shift with increasing environmental dielectric constant. With the combined structure of surface enhanced Raman scattering substrates and rhodamine 6G as a test molecule, the results in this paper show that the absorption has a linear relationship with the local electromagnetic field for insulating substrates, and the electrical property of the substrate has a non-negligible effect on the intensity of the local electromagnetic field and hence the Raman enhancement.

The structure of a heterojunction made up of an (8, 0) carbon nanotube and an (8, 0) boron nitride nanotube is achieved through geometry optimization implemented in the CASTEP package. Based on the optimized geometry, the model of the heterojunction is established. Its transport properties are investigated by combining the nonequilibrium Green's function with density functional theory. Results show that both the lowest unoccupied molecular orbital and the highest occupied molecular orbital mainly locate on the carbon nanotube section. In the current–voltage characteristic of the heterojunction, a rectification feature is revealed.

A possible heating effect on the process of high deposition rate microcrystalline silicon has been studied.It includes the discharge time-accumulating heating effect,discharge power,inter-electrode distance,and total gas flow rate induced heating effect.It is found that the heating effects mentioned above are in some ways quite similar to and in other ways very different from each other.However,all of them will directly or indirectly cause the increase of the substrate surface temperature during the process of depositing microcrystalline silicon thin films,which will affect the properties of the materials with increasing time.This phenomenon is very serious for the high deposition rate of microcrystalline silicon thin films because of the high input power and the relatively small inter-electrode distance needed.Through analysis of the heating effects occurring in the process of depositing microcrystalline silicon,it is proposed that the discharge power and the heating temperature should be as low as possible,and the total gas flow rate and the inter-electrode distance should be suitable so that device-grade high quality deposition rate microcrystalline silicon thin films can be fabricated.

Strained Si CMOS technology is one of the most advanced technologies in present day microelectronics. Electronical conductivity effective mass of strained Si is a key parameter to study electron mobility enhancement. Using K ·P method with the help of perturbation theory, dispersion relation near conduction band valley was determined, including the longitudinal and transverse masses. And then, electronical conductivity effective masses of strained Si on (001),(101) and (111) planes were obtained with respect to stress, splitting energy and directions. It was found that both the [100]and [010]directional electronical conductivity effective masses of strained Si/(001)Si1-xGex and the [010]directional one of strained Si/(101)Si1-xGex decrease with increasing Ge fraction or stress, and both values tend to be constant. The results provide valuable reference to the conduction channel design related to stress and orientation in the strained Si nMOS devices.

Synthesis of coarse-grain diamond crystals is studied in a China-type SPD6×1670T cubic high-pressure apparatus with high exact control system. To synthesize high quality coarse-grain diamond crystals, advanced indirect heat assembly, powder catalyst technology and optimized synthesis craft are used. At last, three kinds of coarsegrain diamond (about 0.85 mm) single crystals with hexahedron, hex-octahedron and octahedron are synthesized successfully under HPHT (about 5.4 GPa, 1300–1450°C). The growth characters of different shape crystals are discussed. The results and techniques might be useful for the production of coarse-grain diamonds.