Responses of Electric-Field Probes Near a Cylindrical Model of the Human Body

A theoretical and experimental study on the response of an E-field probe near a cylindrical model of the human body has been conducted. The body is simulated with a long cylindrical dielectric shell filled with saline water, and a single E-field probe oriented in various directions, or an orthogonal probe is heated near its surface. The model with the probe is illuminated by a TE or TM plane EM wave. The response of the probe was found to be strongly dependent on the probe location with respect to the direction of the incident EM wave, the probe separation from the model surface, the probe orientation and the polarization of the incident EM wave. The effect due to the dielectric shell on the probe response, with and without the presence of saline water, was carefully investigated. In all cases, the agreement between theory and experiment was found to be very good.     

Accurate modeling of the effects of fringing area interface traps on scanning capacitance microscopy measurement

Scanning capacitance microscopy (SCM) is a dopant profile extraction tool with nanometer spatial resolution. While it is based on the high-frequency MOS capacitor theory, there are crucial second-order effects which make the extraction of dopant profile from SCM data a challenging task. Due to the small size of the SCM probe, the trapped charges in the interface traps at the oxide-silicon dioxide interface surrounding the probe significantly affect the measured SCM data through the fringing electric field created by the trapped charges. In this paper, we present numerical simulation results to investigate the nature of SCM dC/dV data in the presence of interface traps. The simulation takes into consideration the traps' response to the ac signal used to measure dC/dV as well as the fringing field of the trapped charge surrounding the probe tip. In this paper, we present an error estimation of experimental SCM dopant concentration extraction when the interface traps and fringing field are ignored. The trap distribution in a typical SCM sample is also investigated.     

Instrumentation for quantitative assessment of intestinal viability

The development of an instrumentation system to quantify the survivability of ischemic intestine is reported. The device is a second-generation effort intended to provide the surgeon with an instrument to give immediate information on the amount of ischemic bowel which will not survive and must be surgically resected. The instrument delivers a precisely-controlled electrical stimulus to a small segment of bowel measures the resulting evoked contractile response. This device, which is termed the electronic contractility meter, was evaluated in a series of preliminary experiments. The instrument consist of two main components: a measurement probe which attaches to the intestine and a signal processing/display module. The probe provides an electrode interface for the electrical stimulus as well as the transducer for the measurement of contractile response. The probe can be detached and gas-sterilized for reuse. The signal processing/display module produces a precisely-controlled electrical stimulus, detects and processes the probe contractility signals, and displays the results     

Modeling Piezoelectric Interfacial Wave Near an Imperfect Interface

The interface wave propagating along an imperfect interface between two piezoelectric half spaces is derived firstly. The wave equations based on the interface modeled, called ＂spring model＂, are presented. The micro-scale structures of the interface for connecting the spring constant with the interface micro-structures are examined. For some simple interface micro-structure, exact dynamic solution is available, and the spring constant is obtained by comparing solutions. For the complex micro structures, it remains as a challenge of micro-mechanics modeling to connect the ＂spring constant＂ and micro-structure.     

Networked telemicromanipulation systems "Haptic Loupe"

In this paper, "Haptic Loupe" telemicromanipulation systems are proposed. We have developed telemicromanipulation systems that enable human operators to perform micro tasks, such as assembly or manufacturing without stress . These systems are based on a scaled bilateral teleoperation system between different structures. The systems are composed of an original six-degrees-of-freedom (6-DOF) parallel link manipulator to carry out micromanipulation and a 6-DOF haptic interface with force feedback. A parallel mechanism is adopted as a slave micromanipulator because of its good features of accuracy and stiffness. The haptic master interface is developed for micromanipulation systems. Haptic device system modeling and a model reference adaptive controller are implemented to compensate for friction forces, which spoil the free motion performance and force response isotropy of the system. Total system performance as a telemicromanipulator system is evaluated by performing some primitive manipulation tasks in a teleoperation experiment. Experimental results are presented and discussed.     

Radiation damage of thermally oxidized MOS capacitors

The influence of preparation parameters and the effect of X-rays (150 keV, 10⁴rad (Si)) on oxide charge Qoxand interface state density Nssin thermally oxidized MOS varactors under different biasing conditions during irradiation has been investigated. The interface state density was determined by the ac conductance method before and after irradiation. The oxide charge has been evaluated with regard to the charge Qssof the interface states. Qsshas beeu discussed with the aid of simple models concerning the energetic distribution and recharge character of the interface states. The results indicate a similar dependence between flatband voltage, interface state density, and normalized oxide charge density as a function of gate bias during irradiation. Furthermore, the so-called "oxidation triangle" of oxide charge before irradiation exists for interface states as well. Calculations on the basis of the Schottky barrier model of the irradiated MOS structure show that the radiation-induced charge exists at both interfaces in the oxide layer. Radiation tolerance of the MOS capacitors as a function of technological parameters is discussed.     

基于探头导纳模型的复介电常数测量技术

基于开口同轴探头的导纳模型,建立被测材料复介电常数与反射系数之间的数值关系。使用矢量网络分析仪测量探头终端的矢量反射系数,利用虚拟仪器构建可视化界面,通过软件编程反演计算来确定被测介质的复介电常数,并对已知材料的测量值、HFSS软件仿真值、模型理论值对比,能够很好地吻合,验证了该模型的准确性。对一些常见介质及吸波材料进行了测量。本方法具有非破坏性,适于现场测量,而且具有设备简单、操作方便直观、测量精度高等优点。     

玻璃基底和表面粗糙度在氮化硅薄膜椭偏测量中的影响

在光谱椭偏测量中,玻璃基底的背反射会给测量结果造成较大影响。针对平板显示器件玻璃基底表面氮化硅镀膜进行了椭偏测量和模型计算。采用相干背反射模型“空气基底空气”计算并拟合得到与厂商数据符合较好的玻璃基底折射率。对氮化硅薄膜采用Tauc Lorentz色散模型进行了分析拟合,讨论了薄膜与基底界面层、表面粗糙度对光学常数及模型拟合的影响,表明在薄膜与基底间晶格失配的情况下,界面层的引入对改善拟合度是必要的。给出了薄膜体系的光学常数、薄膜结构的分析结果。     

A comprehensive analytical and numerical model of polysilicon emitter contacts in bipolar transistors

A comprehensive model-both analytical and numerical-is proposed as a tool to analyze heavily doped emitters of transistors with polycrystalline silicon (polysilicon) contacts. The grains and grain boundaries of polysilicon, the interfacial oxide-like layer between polycrystalline and monocrystalline silicon are lumped respectively into "boxes" in which the drift minority current component is neglected. The mobility reduction of carriers in polysilicon on the whole is explicitly attributed to the additional scattering due to the lattice disorder in the grain boundaries and the carrier tunneling through the interface. The effect of the poly-contacts on transistors can be modeled as a reduced surface recombination velocity for minority carriers in combination with a series emitter resistance for majority carriers. Furthermore, by characterizing the monocrystalline emitter with an effective recombination velocity, the effect of the polysilicon layer on the current gain can be analyzed analytically. Computer simulation is used to verify the assumptions of the model formulation. Using published data [1], the analytical and numerical approaches are compared and it is shown that for these devices a unique combination of physical parameters are needed for the model to fit the data.     

介质探针式精密液位测试仪的研制

本文介绍了一种物质介质界面变化测量探针(介质探针)的研制过程,并且基于此介质探针研发了新型的液位测试仪.同时详细的介绍了这种新型河流模型水位测试仪的软硬件设计方案、以及通信协议的定制.该系统能精确的测量河流模型的液位深度,同时具备数据保存、液晶显示等功能.实验与运行状况表明该系统具有成本低、可靠、高效、实时性强等特点.     

Normal Metal-High Tc Superconductor Point Contact Properties At Millimeter Waves

Experimental results of the response of a metal-high T_c superconductor (BSCCO-2212) point contact to millimeter wave radiation both at room and liquid nitrogen temperatures are presented. Measurements were carried out with and without bias current. An unexpectedly large response signal was observed when the bias current was applied. This effect is explained by the heating of the interface area below the tip of the metallic probe by the alternating current of the millimeter wave. The response signal was compared with that obtained using a Schottky diode.     

双窗口电磁诱导透明的相干瞬态研究

通过求解准A-型四能级系统的含时密度矩阵方程,研究了系统从单窗口电磁诱导透明(EIT)向双窗口EIT转换的相干瞬态过程.该过程表现为一种量子拍频形式,并利用缀饰态理论很好地解释了量子拍频的规律,指出这种量子拍频效应源于射频驱动场所引起劈裂能级间的量子相干.结果表明:当探测场与相应的裸态跃迁能级共振作用时,拍频频率等于射频驱动场Rabi频率的二分之一;当探测场与强射频驱动场和原子系统相互作用所产生的缀饰态跃迁能级共振时,拍频频率等于射频驱动场的Rabi频率.     

The superlattice barrier capacitor: A structure for the investigation of heterojunction interfaces

A symmetric n- GaAs/AlAs-GaAs superlattice/n- GaAs structure has been fabricated and electrical measurements made between 300 and 77 K. At 238 K and below, the C-V characteristics were clearly symmetric, in good agreement with theory. Such a structure can be used as a sensitive probe of the interface defects at the "normal" and "inverted" heterojunction interfaces associated with the barrier. Furthermore, the highly nonlinear C-V characteristic of this symmetric semiconductor capacitor near-zero bias may have unique applications.     

Role of spontaneous polarization in formation of heterojunctions from silicon carbide polytypes

Solution of the Poisson equation is analyzed in terms of the model of a completely depleted contact layer for a heterojunction having as one of its components a noncubic silicon carbide polytype that exhibits a spontaneous polarization P _sp. It is shown that consideration of P _sp leads to broadening of the space charge regions. It is demonstrated that an isotype p-p junction with a quantum well in the valence band of the 3C polytype at the interface with the H-SiC polytype can serve as a model object for studies of the effect exerted by the spontaneous polarization on the properties of SiC heterojunctions. The possibility of a noticeable effect of P _sp on the ground-state energy of an electron in the well is demonstrated for the model with a triangular potential well.     

The VB5 interface

The VB5 interface is an ATM-based broadband interface at the V reference point, the interface between a user access and a service node (SN), also known as the SNI (service node interface) within the ITU-T. The B-ISDN architectural model allows for a number of different user accesses, such as straightforward digital sections and simple multiplexers, but it is anticipated that the most frequent implementation, particularly for mass deployment, will be via a broadband access network (AN) with VB5 interfaces.The VB5 interface is specified in a similar way to its narrowband cousin V5, in two variants – VB5.1, which supports allocation of resources via the management system, and VB5.2, which adds a mechanism for allocating AN resources under the control of the SN, enabling call-by-call concentration in the AN. This paper describes the background to the development of VB5 and explains the two variants VB5.1 and VB5.2.     

玻璃平面波导的热键合制备与界面扩散研究

铒镱共掺磷酸盐玻璃平面波导在散热和抑制非线性效应方面具有独特优势,可开发作为近红外1.5 μm高平均功率固体激光器的增益介质,具有重要意义。文中应用光胶热键合方法制备铒镱共掺磷酸盐玻璃平面波导,研究了预键合阶梯升温过程对键合质量的影响。通过电子探针表面分析（EPMA）得到键合温度和键合时间对键合界面分子扩散层厚度的影响,并根据Fick第二定律,探讨了一维等效假设下的芯层玻璃中的Yb3+扩散机理,建立了热键合过程中的固-固界面分子扩散模型。最终通过选择最优的热处理工艺参数,得到了键合质量良好且键合强度达到11.63 MPa的芯层厚度为100 μm的三明治结构平面波导。     

Consequences of interface corrugation on the lattice dynamics and Raman spectra in high-index AlAs/GaAs superlattices

We have studied the effect of the interface corrugation on the Raman response of (113), (112), (331) and (012)-oriented AlAs/GaAs superlattices. The phonon frequencies and displacements have been calculated using the bond charge model and a supercell approach, and the Raman spectra have been calculated using the bond polarizability model. In (113)-oriented superlattices, the corrugation would give rise to an additional mode coupling and an enhancement of the phonon confinement. The magnitude of these effects and the consequent modifications on the Raman spectra would be quite different for the two interface structures proposed in the literature. For the (112), (331) and (012) superlattices, the modifications induced by the in-plane periodicity would be weak, even in the case of ultrathin superlattices. This is due to the very small height of the interface corrugation and also because the proposed lateral periodicity would not induce any significant mode coupling.     

Gas selectivity of SILAR grown CdS nano-bulk junction

Nano-particles of cadmium sulphide were deposited on cleaned copper substrate by an automated sequential ionic layer adsorption reaction (SILAR) system.The grown nano-bulk junction exhibits Schottky diode behavior.The response of the nano-bulk junction was investigated under oxygen and hydrogen atmospheric conditions.The gas response ratio was found to be 198％ for Oxygen and 34％ for Hydrogen at room temperature.An increase in the operating temperature of the nano-bulk junction resulted in a decrease in their gas response ratio.A logarithmic dependence on the oxygen partial pressure to the junction response was observed,indicating a Temkin isothermal behavior.Work function measurements using a Kelvin probe demonstrate that the exposure to an oxygen atmosphere fails to effectively separate the charges due to the built-in electric field at the interface.Based on the benefits like simple structure,ease of fabrication and response ratio the studied device is a promising candidate for gas detection applications.     

Communicating the Message:Translating tasks into queries in a database context

This paper examines two components of the user-database interface: the data modeling constructs used to represent the database structure and the query language constructs used for data retrieval. From a theoretical perspective, if both the data modeling and query language support high-level abstractions (HLAs), such as generalization and composition, then the "semantic distance" between the user and the interface will be reduced. We used an in-depth verbal protocol study to explore how users were able to effectively complete two tasks: constructing a data model with HLAs and formulating queries against the data model. Results suggest that a successful strategy for modeling with HLAs involves the systematic transition between higher and lower levels of abstraction. In addition, there is some support for the idea that there is a "productivity payoff" to modeling with HLAs, because subsequent query can be simplified.