Anomalously Strong Scattering of Spontaneously Produced Laser Radiation in the First Free-Electron Laser and Study of Free-Electron Two-Quantum Stark Lasing in an Electric Wiggler with Quantum-Wiggler Electrodynamics

We calculate the scattering cross section of an electron with respect to the spontaneously produced laser radiation in the first free-electron laser （FEL） with quantum-wiggler electrodynamics （QWD）. The cross section is 1016 times the Thomson cross section, confirming the result obtained by a previous analysis of the experimental data. A QWD calculation show that spontaneous emission in an FEL using only an electric wiggler can be very strong while amplification through net stimulated emission is practically negligible.     

Cumulative quantum work-deficit versus entanglement in the dynamics of an infinite spin chain

We find that the dynamical phase transition (DPT) in nearest-neighbor bipartite entanglement of time-evolved states of the anisotropic infinite quantum XY spin chain, in a transverse time-dependent magnetic field, can be quantitatively characterized by the dynamics of an information-theoretic quantum correlation measure, namely, quantum work-deficit (QWD). We show that only those nonequilibrium states exhibit entanglement resurrection after death, on changing the field parameter during the DPT, for which the cumulative bipartite QWD is above a threshold. The results point to an interesting inter-relation between two quantum correlation measures that are conceptualized from different perspectives.     

Quantum weakdynamics as an SU(3)_I gauge theory: Grand unification of strong and electroweak interactions

Quantum weakdynamics (QWD) as an gauge theory with the vacuum term is considered to be the unification of the electroweak interaction as an gauge theory. The grand unification of beyond the standard model is established by the group . The grand unified interactions break down to weak and strong interactions at a new grand unification scale, GeV, through dynamical spontaneous symmetry breaking (DSSB); the weak and strong coupling constants are the same, , at this scale. DSSB is realized by the condensation of scalar fields, postulated to be spatially longitudinal components of gauge bosons, instead of Higgs particles. Quark and lepton family generation, the Weinberg angle , and the Cabbibo angle are predicted. The electroweak coupling constants are , , , and ; there are symmetric isospin interactions. Received: 21 January 2001 / Published online: 21 November 2001     

Electric-Wiggler-Enhanced Three-Quantum Scattering and the Output Power Affected by this Scattering in a Free-Electron Laser

We derive the cross section of scattering through the three-quantum interaction of an electron with the incident laser field, the emitted photon, and an axial electrostatic field produced by the magnetic wiggler in the magnetic wiggler acting as the sole zeroth-order perturbing classical field in the first free-electron laser （FEL）. In the derivation, we apply quantum-wiggler electrodynamics （QWD）. We find that this scattering predominates the usual two-quantum scattering. The output power of spontaneous free-electron two-quantum Stark emission driven by the above electrostatic field attenuated by the three-quantum scattering agrees within a factor of 10 with the measured power in the case of the first FEL.     

闪光－I加速器的预脉冲电压研究

分析了闪光－Ｉ的预脉冲电压和降低预脉冲电压的效果,采用容性电压探测器实现了对阴阳极之间预脉冲电压的测量。在比较实测波形和预计波形后,提出了改进的等效电路模型,并指出了Ｂｌｕｍｌｅｉｎ中筒与二极管之间耦合电容的影响,提出了进一步降低预脉冲电压的途径。     

A threshold voltage analytical model for high-k gate dielectric MOSFETs with fully overlapped lightly doped drain structures

We investigate the influence of voltage drop across the lightly doped drain(LDD) region and the built-in potential on MOSFETs,and develop a threshold voltage model for high-k gate dielectric MOSFETs with fully overlapped LDD structures by solving the two-dimensional Poisson’s equation in the silicon and gate dielectric layers.The model can predict the fringing-induced barrier lowering effect and the short channel effect.It is also valid for non-LDD MOSFETs.Based on this model,the relationship between threshold voltage roll-off and three parameters,channel length,drain voltage and gate dielectric permittivity,is investigated.Compared with the non-LDD MOSFET,the LDD MOSFET depends slightly on channel length,drain voltage,and gate dielectric permittivity.The model is verified at the end of the paper.     

Two-dimensional threshold voltage model of nanoscale silicon-on-insulator tunneling field-effect transistor

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 the TFET device design, simulation, and fabrication.     

LCC谐振变换器的电路建模与参数设计

对用于高压场合的LCC谐振变换器进行了分析和研究,采用基波近似法推导等效模型,建立了谐振电路的大信号模型和等效模型,对LCC谐振变换器的稳态特性进行分析,采用了一种以输入阻抗角为限定条件的参数设计方法,该方法可以实现谐振变换器零电压开关的同时兼顾谐振电流对效率的影响。在大信号模型的基础上,建立了小信号模型,得到输出电压与输入占空比之间的传递函数,从而建立闭环系统,实现电压的宽范围输出。通过Simulink仿真验证了所设计的LCC谐振变换器可实现全负载范围的零电压开关(ZVS),说明了设计方法的可行性。     

Two-dimensional threshold voltage model of a nanoscale silicon-on-insulator tunneling field-effect transistor

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.     

应变Si沟道nMOSFET阈值电压模型

在研究分析弛豫SiGe衬底上的应变Si 沟道nMOSFET纵向电势分布的基础上,建立了应变Si nMOSFET阈值电压模型,并利用该模型对不同的器件结构参数进行仿真,获得了阈值电压与SiGe层掺杂浓度和Ge组分的关系、阈值电压偏移量与SiGe层中Ge组分的关系、阈值电压与应变Si层掺杂浓度和厚度的关系. 分析结果表明：阈值电压随SiGe层中Ge组分的提高而降低,随着SiGe层的掺杂浓度的提高而增大;阈值电压随应变Si层的掺杂浓度的提高而增大,随应变Si层厚度增大而增大. 该模型为应变Si 器件阈值电压设计 关键词： 应变硅 阈值电压 电势分布 反型层     

Target voltage behaviour of a vanadium-oxide thin film during reactive magnetron sputtering

This paper simulates reactive magnetron-sputtering in constant current mode in a Vanadium-O 2 /Ar system equipped with a DC power supply by adopting both kinetics model and Berg’s model.The target voltage during the reactive sputtering has been investigated as a function of reactive gas flow.Both experiments and simulations demonstrate a hysteresis curve with respect to the oxygen supply.The time-dependent variation of the target mode is studied by measuring the target voltage for various reactive oxygen gas flows and pre-sputtering times.The presputtering time increases with the increased initial target voltage.Furthermore,a corresponding time-dependent model simulating target voltage changes is also proposed.Based on these simulations,we find some relationships between the discharge voltage behaviour and the properties of the formed oxide.In this way,a better understanding of the target voltage changes during reactive sputtering can be achieved.We conclude that the presented theoretical models for parameter-dependent case and time-dependent case are in qualitative agreement with the experimental results and can be used to comprehend the target voltage behaviour in the deposition of vanadium oxide thin films.     

金属-氧化物-半导体场效应管辐射效应模型研究

基于氧化层陷阱电荷以及界面陷阱电荷的产生动力学以及辐射应力损伤的微观机理,推导出了金属-氧化物-半导体场效应管(MOSFET)中辐射应力引起的氧化层陷阱电荷、界面陷阱电荷导致的阈值电压漂移量与辐射剂量之间定量关系的模型. 根据模型可以得到:低剂量情况下,氧化层陷阱电荷与界面陷阱电荷导致的阈值电压漂移量与辐射剂量成正比;高剂量情况下,氧化层陷阱电荷导致的阈值电压漂移量发生饱和, 其峰值与辐射剂量无关,界面陷阱电荷导致的阈值电压漂移量与辐射剂量呈指数关系. 另外,模型还表明氧化层陷阱电荷与界面陷阱电荷在不同的辐射剂量点开始产生饱和现象, 其中界面陷阱电荷先于氧化层陷阱电荷产生饱和现象.最后,用实验验证了该模型的正确性. 该模型可以较为准确地预测辐射应力作用下MOSFET的退化情况.     

SUPERCONDUCTING JUNCTIONS IN THE CASE OF CORRELATED SYMMETRIC NOISES

We study two models for Josephson junctions, i.e.,a Gaussian white noise model and a symmetric dichotomous noises model. In this study we find that the correlated symmetric noises can produce a net voltage. This phenomenon is due to the correlation between the additive and the multiplicative noises. We show some characteristic features for this phenomenon: the net voltage is always negative and has a peak value when the strength of the additive noises varies for the former model(or when the strengths of the noises vary for the latter model). The results provide a theoretical foundation for reducing the net voltage caused by the correlated symmetric noises.     

Response model of resistance-type microbolometer

There are certain limitations in the application of uncooled focal plane array (FPA) detectors owing to the shortage of the response model that transforms bias voltage to analog output voltage at a certain constant radiation power; Moreover, bias voltage affects the input radiation gain. In this study, we established a response model of a microbolometer through examining the detection theory of a microbolometer and the heat balance equation under the condition of the pulse voltage bias. In the establishment process, we simplified the heat balance equation in order to acquire a simple answer. The experimental data show that, in the full variable range of bias voltages, the biggest difference between the model data and the experiment data is about 0.7 K. This model can reflect the real responses of microbolometers with only small differences, which are acceptable in engineering applications.     

新型高速半导体器件IMOS阈值电压解析模型

本文在研究IMOS器件结构的基础上, 分析了该器件不同区域的表面电场, 结合雪崩击穿条件, 建立了P-IMOS的阈值电压解析模型. 应用MATLAB对该器件阈值电压模型与源漏电压、栅长和硅层厚度的关系进行了数值分析, 并用二维器件仿真工具ISE进行了验证. 结果表明, 源电压越大, 阈值电压值越小; 栅长所占比例越大, 阈值电压值越小, 硅层厚度越小, 阈值电压值越小. 本文提出的模型与ISE仿真结果一致, 也与文献报道符合. 这种新型高速半导体器件IMOS阈值电压解析模型的建立为该高性能器件及对应电路的设计、仿真和制造提供了重要的参考.     

热声转换的声表面波电压传感机制

提出了一种基于热声转换的高灵敏声表面波(SAW)电压传感机制并开展实验验证。从传热角度以及微扰理论出发建立了基于热声转换机制的SAW电压传感理论模型,探索了结构参数以及环境因素对SAW电压传感器灵敏度的影响规律。为了验证理论模型,在Y切石英基底上同芯片集成设计MEMS微型加热器与200 MHz声表面波器件以制备SAW电压传感器件,并搭建电压测试平台对传感器件开展性能测试。实验结果表明所制备的SAW传感器件电压与频率响应之间具有二次线性关系且在室温(20℃)下具有与理论相近的电压灵敏度(22.4 kHz/V),此外实验获得的环境温度对电压灵敏度的影响规律与理论相符。基于热声转换机制的SAW电压传感器能够显著的提高电压检测灵敏度。     

亚纳秒气体开关中气体击穿的数值计算

 对亚纳秒气体开关的放电过程，提出了气体击穿阶段的物理与数学模型以及数值计算方法，并对氢气和氮气的这一击穿过程进行了数值仿真。对于1mm氮气间隙，计算了充电电压波形为纳秒级上升的斜角平顶波时，开关放电时延以及击穿电压随气压和充电电压上升时间的变化。对于氢气，利用美国Sandia实验室的一个实验结果对数值仿真方法进行了验证，所得到的计算结果与实验结果很好地吻合，初步表明所建立的物理模型与计算方法的正确性。     

One-dimensional single and multipulse simulations of the ON/OFFvoltages and the bistable margin for He, Xe, and He/Xe filled plasmadisplay pixels

A one-dimensional plasma model developed for AC plasma display pixels is used to perform multipulse and single-pulse simulations to model the maximum sustain voltages, the minimum sustain voltages, and the voltage margins for 100% helium, 100% xenon, and for 2% xenon in helium and a 400 torr pressure (p) and a gap (L) of 100 μm. The multipulse simulations describe the growth in wall voltage at the so-called ON voltage and the decay in wall voltage at the so-called OFF voltage. For square wave forms, the ON voltage is the voltage at which a pixel attains to a stable operation in which a discharge occurs in each succeeding pulse and the wall voltage equal to the applied voltage. The OFF voltage is the voltage at which a pixel that is ON goes off and no further discharges occur. Experimental data for helium show the hysteresis in the discharge current observed when the voltage is increased to turn ON pixels and then reduced to turn OFF-pixels in a panel. Simulations which match the helium data are also shown. The difference between the ON and OFF voltages defines the bistable margin. For the helium-xenon Penning mixture, the ON and OFF voltages determined by multipulse simulations are almost identical to the values obtained from the wall voltage transfer curve method. In the helium-xenon Penning mixture, the ionization rate for xenon ground state increases dramatically compared to its ionization rate in pure xenon due to the modification in the electron velocity distribution function in the mixture. This feature provides enhanced volumetric ionization in the discharge and hence a rapid growth rate of the wall voltage which is desirable for a sharp transition from OFF to ON in a pixel     

Directed transport in quantum Hall bilayers

The pseudo-spin model for a double layer quantum Hall system with the total landau level filling factor ν=1 is discussed. In contrast to the “traditional” model where the interlayer voltage enters as a static magnetic field along pseudo-spin hard axis, taking into account the realistic experimental situation, in our model we interpret the influence of applied voltage as a source of additional relaxation process in the double layer system. We show that the Landau-Lifshitz equation for the considered pseudo-magnetic system well describes existing experimental data and reduces to the dc driven and damped sine-Gordon equation. As a result, the mentioned model predicts novel directed intra-layer transport phenomenon in the system. In particular, unidirectional intra-layer energy transport can be realized due to the motion of topological kinks induced by applied voltage. Experimentally this should be manifested as counter-propagating intra-layer inhomogeneous charge currents proportional to the interlayer voltage and total topological charge of the pseudo-spin system.     

多阶平衡式Cockcroft-Walton电路的等效模型与输出特性

基于电路的输出效果,采用电荷转移原理阐述平衡式Cockcroft-Walton(C-W)倍压电路较为复杂的物理过程,将电路中二极管的非线性导通特性等效为周期性线性导通的数学解析模型,推导了表征其输出特性的纹波电压和带载输出电压的理论输出表达式。采用仿真软件对比了基本式和平衡式C-W电路的输出特性曲线,结果表明平衡式拓扑结构的纹波大小约为基本式拓扑结构的8%。同时建立的多阶平衡式C-W电路纹波电压理论模型计算值略低于电路软件仿真值,带载输出电压的理论模型计算值与仿真值的相对误差低于10%。