Impact of phosphorus doping to multiple-stacked Si quantum dots on electron emission properties

We have fabricated multiple-stacked phosphorous doped Si quantum dots (P-doped Si-QDs) embedded in SiO₂ on n-Si(100) structures and characterized their field electron emission under DC bias application to semitransparent Au top-electrodes. At applied biases of −8 V and over, the electron emission signal with a peak kinetic energy at ~2.0 eV was detected. In addition, we also found that the electron emission was drastically enhanced with an increase in the applied DC bias over −11 V. The applied bias dependence of emission intensities shows that the P-doped Si-QDs is effective to improve electron emission efficiency while undoped Si-QDs stack is suited to low power operation. This indicates that electric field was reduced near the top side of the Si-QDs stack and an increase in electron injection rate from the n-Si(100) to the dots by phosphorus doping plays a role on high efficient electron emission from the Si-QDs stacked structures.     

Study of rectifying property of ITO/PI/TIPS-pentacene/Au diodes by electric field induced optical second harmonic generation

By using time-resolved electric field induced optical second harmonic generation (TR-EFISHG) measurement, we studied the rectifying property of organic double-layer diodes with a structure of indium-tin-oxide/polyimide/6,13-Bis(triisopropylsilylethynyl)-pentacene/gold (ITO/PI/TIPS-pentacene/Au). Upon application of a step voltage to the diodes, the TR-EFISHG probed the electric field changes induced in the TIPS-pentacene layer by hole injection from the ITO electrode, followed by the hole accumulation at the PI/TIPS-pentacene interface. Consequently, the electric field distributions in the diodes before and after the carrier injection were traced with accumulated charges at the PI/TIPS-pentacene interface, depending on the DC biasing applied to the diodes. Analyzing the carrier behavior in ITO/PI/TIPS-pentacene/Au on the basis of a Maxwell–Wagner model, we discussed the rectifying property of the diodes in terms of DC biasing effect, i.e., threshold-voltage shift, and concluded that space charge limited current process that flows across the PI layer governs the rectification of the diodes. Using the TR-EFISHG measurement is an effective way to study the rectifying property of organic double-layer diodes.     

Microwave breakdown voltages in hydrogen from DC data

The general microwave breakdown characteristic in hydrogen is obtained from the DC dependence of the ionization coefficient and electron mean energy on the reduced electric field, using the basic equations of motion of electrons in a high frequency electric field. Excellent agreement is obtained between the calculated characteristic and experimental values from the literature. With the aid of the derived effective reduced electric field concept, specific breakdown characteristics are then obtained for given microwave cavities. These also agree well with experimental results except well below the Paschen minimum, confirming the validity of the concept. The subject is presented as a self-contained entity and its analogy with an applied crossed magnetic field is emphasized. A direct comparison between the microwave and the DC Paschen formula is made.     

Spin response of 2D electrons to a lateral electric field

The spin orientation of two-dimensional (2D) electrons by a lateral electric field is considered. The electron dispersion law is assumed to contain linear terms due to the spin-orbit band splitting in an asymmetric quantum well. The coefficient of spin orientation in a DC electric field is found. The mean electron spin is oriented in the sample plane perpendicularly to the electric field. The interaction of an AC electric field with spins of 2D electrons is studied. It is shown that transitions between different spin states give rise to a narrow absorption band. These states are mixed with 2D plasmons in the frequency range related to these transitions, with the result being that the plasmon spectrum is modified and a new type of oscillations arises (spin-plasmon polariton). The problem of the generation of spin-plasmon polaritons by an external field is solved.     

光折变GaAs在直流电场下双光束耦合的增强效应(英文)

Two-beam coupling and energy transfer occur, because of the birefrin-gent nature of the photorefractive grating formed by the two interfering beams. We report the observation of the enhanced two-beam coupling in the semi-insulation Cr-doped GaAs crystals at 1.15μm polarized beam from a CW He-Ne infrared laser under DC electric fields.We have measured the gain coefficients as a function of the applied DC electric field and the grating spacing. The optimum experimental crystallographic orientation in cubic photo-optic crystals with on applied field has been discussed. These measured results are close to the predicted theoretical values.     

Influence of electron mobility modeling on DC I-V characteristicsof WZ-GaN MESFET

We report on the drift-diffusion based simulation of a wurtzite (WZ) GaN MESFET. The main emphasis is put on the influence of electron mobility modeling on DC current-voltage (I-V) characteristics of the WZ-GaN MESFET. Two different analytical expressions are used for the electron mobility as a function of electric field. The first model is based on a simple saturation of the steady-state drift velocity with electric field (conventional three-parameter model). The other model is more realistic since it well reproduces the drift velocity-field characteristics obtained by Monte Carlo (MC) calculations, revealing the peak drift velocity with subsequent saturation at higher electric fields. Thus, it should be implemented in the drift-diffusion model for a following device simulation. However, the MC electron transport data for WZ-GaN are influenced by the specific choice of the material and band structure parameters, resulting in a variation of drift velocity-field characteristics. In addition, it should be noted that the MC simulation also neglects crystal defects in GaN, which, for example, might lead to uncontrolled electron compensation and additional electron scattering. In the present study we show that the DC I-V characteristics of the WZ-GaN MESFET are strongly affected by the MC-like electron mobility model, in particular by the peak steady-state velocity and the shape of the velocity-field characteristics even for the same drift velocity saturation level     

电致发光聚合物在外电场中行为的动力学研究

用电子－晶格耦合的紧束缚模型和求介实时牛顿动力学方程的方法研究了具有额外电子和空穴的电致发光高分子在外电场中的行为。发现外电场注入的额外电子和空穴使电致发光高分子晶格弛豫,形成双极化子激子;并存在一个临界电场,当外电场大于或者等于临界电场时,双极化子激子解离成正、负极化子,导致发光猝灭．该结果与电致发光高分子的光荧光被强电场猝灭的实验现象一致．这个一致性反映了双极化子激子是电致发光高分子中的一种发光实体,说明了电致发光高分子在强电场下光荧光猝灭的物理原因是在强电场作用下电致发光高分子中的双极化子激子被解离成正、负极化子     

Effects of electric field during deposition on spray deposited indium‐doped zinc oxide films

Indium‐doped zinc oxide (IZO) thin films were deposited on a glass substrate using spray technique with a direct current (DC) voltage applied to the nozzle to create an electric field during deposition. It was found that the presence of the electric field has a strong effect on doping efficiency, structural, electrical, and optical properties. Incorporation of indium in ZnO was confirmed by the Rutherford back scattering and X‐ray diffraction peak analysis. Scanning electron microscope micrograph showed that the surface morphology changed from rice‐like structure to flower‐like compact structure. The electrical resistivity of IZO film prepared under the electric field was 2 × 10⁻³ Ω cm, transmission in the visible region was more than about 80%, and figure of merit (Φ_TC) was 3.39 × 10⁻³ Ω⁻¹. The films deposited under the electric field showed a band gap narrowing, which is explained using the many body effects in the perturbation theory. Spray deposited IZO film under the electric field was shown to be useful for making self‐cleaning top glass in solar cell module fabrication. Copyright © 2015 John Wiley & Sons, Ltd.     

用“不变本征算符法 ”求解均匀外电场中带电谐振子的量子化能谱

采用不变本征算符法求出均匀外场中带电谐振子的能级间隔,利用“积分变换法”求出均匀外场中带电谐振子的基态能量和相应波函数,通过分析推求出均匀外场中带电谐振子的量子化能谱。     

Induced second-harmonic generation in planar waveguides by anexternally applied periodic DC electric field: efficiency as a functionof field structure

The efficiency of second-harmonic generation (SHG) induced by an externally applied periodic DC electric field was investigated. A finite element method was used to find the static electric field due to different interdigitated electrode structures. The resulting fields were used to calculate the overlap integrals which determine the SHG efficiency in an optical waveguide. The results show that there are reasonable differences in SHG efficiencies for the structures investigated     

Hot electron energy relaxation in quantizing magnetic fields

A systematic study of the radiative recombination of hot electrons between Landau levels in several n-InSb samples has been carried out as a function of the free electron concentration and the applied electric and magnetic fields (E ～ H). The magnetic field range investigated was 0.5 to 3.0 T. Electron temperatures are derived in dependence of the total electric and the magnetic field applied. The carrier heating is impeded with increasing electron concentration and also with increasing magnetic field. From the direct observation of the recombination radiation intensity on electric field response the electron lifetime in the first Landau level is found to be less than 10^?8. The results obtained are discussed in light of a new theoretical approach. We give evidence that electron-electron scattering plays an important role both for the carrier distribution established and for the electron lifetime in the first Landau level.     

电场对非对称半抛物量子阱中的子带内跃迁引起的线性与非线性折射率改变的影响

利用量子力学中密度矩阵及谐振子变换与数值求解相结合的方法,理论考察了带偏置电场的非对称半抛物量子阱中的子带内跃迁引起的线性与非线性折射率改变特性．以GaAs材料参数计算了总折射率改变对入射光的强度、半抛物量子阱受限势频率、外加直流电场强度的依赖关系．结果发现,总折射率改变敏感地依赖于这些因素．     

应用于高Q跨导-电容带通滤波器的线性跨导运放设计

设计了一种具有高的直流增益的宽带线性全差分跨导运放.一方面,并联一个工作在线性区的场效应管来补偿直流三阶系数,得到了一种应用于连续时间滤波器、增加跨导器饱和区输入信号幅度的简单方法.另一方面,结合负电阻电路提高了输出阻抗,实现高的直流增益而不需要额外的内部结点,并减小了因有限直流增益和寄生电容引起的相位偏差.将此全差分跨导运放应用于0.18μmCMOS工艺二阶带通滤波器,在3.3V电源电压、输入峰峰值1V时,HSPICE仿真结果的总谐波失真小于40dB,中心频率为20MHz,3dB带宽为0.18MHz,即Q为110.     

Numerical calculation of gyromonotron parameters using orbital theory

In this paper, the orbital equations of electron motion in the gyroton are derived, starting from the fundamental equations of relativistic electron motion. These equations are applicable to the general case of arbitrary TE_mnl mode with varying DC magnetic field B₀(z) and consider the effect of the RF magnetic field. The calculation formulae for gyromonotron parameters are given, The effect of the longitudinal field profile in an open-ended cavity is discussed, and the computation method and program are briefly described. As examples, numerical results for the gyromonotron in the X and Ka bands in terms of orbital theory are given. For the gyromonotron operating at the TE₀₁₁ mode and fundamental cyclotron harmonic in the X band, and at the TE₀₂₁, mode and second harmonic in the Ka band, orbital efficiencies of 72% and 40% are obtained respectively. Some problems about making use of the orbital equations to calculate the case with varying DC magnetic field or higher TE modes are also discussed.     

计算二维半导体体系电子能带的ATM(英文)

It is pointed out that in terms of the asymptotic transfer method (ATM) suggested by us, the electron subbands and wavefunctions can be solved consistently for both type-I and type-Ⅱ semiconductor multi-quantum-well systems in which the bandedges of conduction bands and valence bands are not flat (oblique lines or curves). As illustrative examples,we performed a self-consistent calculation of electron subbands and wavefunctions of a Ga1-xAlxAs sawtooth superlattice taking account of the variation of the effective mass of electrons with the concentration of Al. We also finished a calculation of electron subbands of type-Ⅱ semiconductor multi-quantum-well systems when an electric field was applied along the growth axis. It is shown that for type-Ⅱ semiconductor multi-quantum-well systems the application of an electric field also results in a strong localization of the eigenstates.     

一种基于PDLC-KIO_3的新型光倍频开关设计与实现

利用聚合物分散液晶(PDLC)的开关特性与KIO3微晶体的非线性光学特性,研制出具有倍频效应(SHG)并且倍频光强电控可调谐的光变频开关。将YAG激光脉冲入射到开关器件,通过调制施加在开关上的驱动电压,当光开关闭合时,可阻挡基频光脉冲,抑制SHG,当光开关开启时,可在散射光路中观察到显著的SHG,开、关态倍频光强对比度可达6∶1。实验发现,驱动电压在0～80 V间,倍频光强能够实现近似线性的调制。测试表明,该变频开关的响应时间为20 ms。     

Simple estimation of equivalent magnetic dipole moment tocharacterize ELF magnetic fields generated by electric appliancesincorporating harmonics

A simple method of quantifying the ELF (extremely low frequency) magnetic field distribution around electric appliances, which takes the harmonics into account, is newly proposed. The proposed method involves: (1) a simple estimation of the position of an equivalent magnetic dipole moment inside an appliance, using two magnetic field meters; (2) identification of the amplitude of the dipole moment magnetic-field measurements at certain points; and (3) calculation of the magnetic field distribution around the appliance using the estimated dipole moment. In this method, the dipole moment vector is assumed to be a similar value by allowing an uncertainty of 6 dB in the estimated magnetic field, which enables easy estimation of the dipole moment. In addition, the frequency characteristics of the magnetic field are taken into account by considering the harmonic components in the magnetic field waveform. The proposed method was applied to 13 types of appliances, and their equivalent magnetic dipole moments and harmonic components were determined. The results revealed that the proposed method is applicable to many electric appliances. The conditions required for the adoption of the method were also clarified     

Losses in a high-temperature superconductor exposed to AC and DCtransport currents and magnetic fields

Summary form only given, as follows. The development of high-temperature superconductors (HTSs) is for the moment intensive and it is likely that HTSs will be used in different electric devices in a few years. In some of these devices that conductor will be exposed to both AC and DC transport currents and magnetic fields. In the design of electric devices, the power loss is indeed one of the most important parameters. Therefore there is a need of models that predict the power loss in an HTS under application-like conditions. In this paper, the authors present a semi-empirical model including a transport current and an applied magnetic field with both AC and DC components. The semi-empirical model is mainly based on the critical state theory. The results of the model are compared and found to be in good agreement with experimental results obtained with a calorimetric experimental set-up. The power loss was measured on a multi-filamentary Bi-2223 tape as function of transport current and applied magnetic field at a fixed temperature and frequency     

Enhancement of high-harmonic gyrotron gain by a dielectric rod

A dielectric rod is shown to reduce the energy requirements of the electron beam for high-harmonic gyrotron operation. A large interaction filling factor can occur for moderate-energy electrons (～80 keV) spiralling around the rod within the evanescent region of a dielectric waveguide mode. Since the magnetic field strength is reduced by an order of magnitude in an interaction at the tenth harmonic of the cyclotron frequency, a submillimeter-wave gyrotron is now truly feasible because the acceleration voltages can be conveniently produced by DC power supplies.     

±800kV云广UHVDC输电线路合成电场测试与分析

通过开展不同运行方式下、不同海拔高度处直流输电线路合成电场的实测,分析了直流输电过程中合成电场的特性,总结了运行方式、气象条件和海拔高度对直流输电线路合成电场的影响规律,为特高压技术的发展和环境评估提供了有力的数据支持。