Comprehensive modeling of electrochemical metallization memory cells

This paper reviews our previous theoretical studies on the simulation and modeling of resistively switching electrochemical metallization memory devices. The focus is on the current understanding of the dynamic behavior of this type of memory cells. A wide range of simulation scales is presented ranging from atomistic kinetic Monte Carlo models to 1D compact and analytical models. While these models show consistent results in the mean dynamic behavior, they address different aspects of the device behavior. With the compact and analytical models, the dynamic behavior on timescales ranging from nanoseconds to thousands of seconds can be investigated. The computationally more expensive multidimensional continuum models and kinetic Monte Carlo models, in contrast, give additional information on the detailed filamentary growth and dissolution mechanism, which is the origin of the resistance switching effect in electrochemical metallization memory cells. Using the different models, the different aspects of the resistance switching effect such as switching dynamics, multilevel programming, filament shape, polyfilamentary switching, variability, quantized conduction and polarity-independent filament dissolution are addressed. Moreover, it will be discussed how the models need to be extended in order to address further properties of the switching process.     

Nanomagnetic logic: compact modeling of field-coupled computing devices for system investigations

In this paper we investigate error rates of nanomagnetic logic devices with perpendicular magnetization by compact modeling. Two different types of nanomagnets for information propagation and logic computing are introduced. The switching behavior of field-coupled nanomagnets is measured and analyzed. A compact model is derived from physics and experimental results are applied to the magnetic compact model. General requirements for fabrication parameters and clocking fields for reliable operation are extracted. We perform simulations and measurements on single devices to demonstrate the accuracy of the macromodel. Simulations on complex systems show that the error rate of a field-coupled magnetic system strongly depends on the variation of the switching field and the strength of the coupling field between the nanomagnets. The error rate of a 1-bit full adder is investigated for varying dot parameters. The results demonstrate the importance of fast simulation tools for investigations on the design of nanomagnetic computing devices and systems.     

功率开关器件多时间尺度瞬态模型(Ⅰ)——开关特性与瞬态建模

开关模式是电力电子系统实施电磁能量变换的基本模式,功率半导体器件的开关特性则成为这种能量变换的关键属性。从开关特性的角度出发,基于对器件开关特性和对电力电子系统多时间尺度特性的认识,提出一组功率开关器件多时间尺度瞬态模型。根据时间尺度的不同选取不同的瞬态模型来描述器件的开关瞬态过程,并反映不同的开关特性。所提多时间尺度瞬态模型,参数可直接从器件数据手册中提取,对提取方法进行较详细的阐述。所提的功率开关器件多时间尺度瞬态模型在装置和系统的分析设计中具有很强的实用性。     

10kV配电变压器自动调压的研究以及试验分析

针对配电变压器机械式有载调压装置复杂、调压不方便等问题,提出一种基于电力电子开关的5档自动调压技术方案。采用启动保护电路,避免电力电子开关承受合闸电压和励磁涌流冲击,保证电力电子开关退出时变压器的正常运行;考虑变压器高压侧绕组不同接线方式,分析开关器件两端承受的电压以及分接头对地电压的分布情况,为电力电子开关器件的参数选择提供参考。结果表明高压侧为星形接线的中性点调压方式更加有利于电力电子器件的工作,高压侧为三角形接线的中部调压方式对于电力电子器件的工作电压以及隔离电压均有较高的要求。在完成电路设计与器件选型的基础上,研制了基于电力电子开关的自动有载调压变压器,并安装于现场试运行。理论研究、仿真分析、样机试验以及上网试运行均表明所提方案具有可行性与可靠性。     

Multiscale modeling of oxide RRAM devices for memory applications: from material properties to device performance

RRAM devices have been subjected to intense research efforts and are proposed for nonvolatile memory and neuromorphic applications. In this paper we describe a multiscale modeling platform connecting the microscopic properties of the resistive switching material to the electrical characteristics and operation of RRAM devices. The platform allows self-consistently modeling the charge and ion transport and the material structural modifications occurring during RRAM operations and reliability, i.e., conductive filament creation and partial disruption. It allows describing the electrical behavior (current, forming, switching, cycling, reliability tests) of RRAM devices in static and transient conditions and their dependence on external conditions (e.g., temperature). Thanks to the kinetic Monte Carlo approach, the inherent variability of physical processes is properly accounted for. Simulation results can be used both to investigate material properties (including atomic defect distributions) and to optimize stack and bias pulses for optimum device performances and reliability.     

Dynamic model of direct matrix converter and its experimental validation

Power electronics is a major candidate in the ongoing research of electrical power grids because they can provide better control with more information (voltage ratio, efficiency, power flow direction, etc.) than the all‐passive solutions such as transformers and so forth. Power electronic transformer has the possibility to replace the conventional one by ac/ac matrix converter with high‐frequency compact electronic transformers. In this work, a dynamic model of matrix converter is studied and issues such as efficiency, voltage ratio limitation, and transient behavior are discussed and the equivalent numerical calculations are presented. Moreover, an experimental converter is built to validate the numerical results and also to describe the switching frequency impact on the operation. It is concluded that the control creates voltage ratio saturation and high‐switching frequency results in lower efficiency values. On the other hand, efficiency can be increased by using resonances of the circuit, which can also provide higher operating frequencies. Copyright © 2015 John Wiley & Sons, Ltd.     

基于实时仿真的ADC模型参数优化方法

采用伴随离散电路(ADC)建模方法时系统矩阵为常系数矩阵,大幅降低了实时仿真求解的计算量。但是将电力电子开关器件等效为L/C模型会造成其在开关过程中产生振荡现象,从而导致仿真误差。分析了采用ADC建模方法时电力电子器件开关等效导纳G_s与其两端电压、流过电流的误差关系,通过建立损耗函数,研究了最优G_s参数的选取方法;以基于LCL滤波的三相电压源型脉宽调制整流器为例,对G_s参数优化方法进行了离线仿真验证;在现场可编辑门阵列实现仿真模型时,基于Vivado高层次综合工具可以显著简化设计和仿真任务,缩短设计时间并提高可靠性。     

Resistive switching memory using biomaterials

Resistive switching memory (ReRAM) is emerging as a developed technology for a new generation of non-volatile memory devices. Natural organic biomaterials are potential elements of environmentally-benign, biocompatible, and biodegradable electronic devices for information storage and resorbable medical implants. Here, we highlight progress in exploiting biomaterials to fabricate a special category of bio-nanoelectronic memories called biodegradable resistive random access memory (bio-ReRAM). Bio-ReRAMs are beneficial because they are non-toxic and environmentally benign. Various types of biomaterials with their chemical compound, bio-ReRAM device design and structure, their relevance resistive switching (RS) behavior, and conduction mechanism are considered in detail. Particularly, we report physically-transient devices, their corresponding switching mechanism, and their dissolution by immersion in water. Finally, we review recent progress in the development of various types of flexible bio-ReRAMs, focusing on their flexibility and reliability as bendable nanoelectronics. Because most of these devices are candidates to become wearable, skin-compatible, and even digestible smart electronics, we discuss the future improvement of natural materials and the perspective of novel bio-ReRAMs.     

Photonics for switching and routing

The ongoing growth of data traffic from existing and new applications poses a challenge to the packet-switched network infrastructure. High-capacity transport can be achieved in such networks by using dense wavelength-division-multiplexed systems, and reconfigurable optical add-drop multiplexers allow the optical layer to provision wavelength-based circuits between routing nodes. However, construction of the high-capacity packet routers provides significant scaling issues due to complexity, interconnect, and thermal limits. In this paper we will not seek to cover all aspects of optical packet switching and routing but outline some of the challenges facing the construction of such future routers and describe the role photonics can have in overcoming some of these issues. We will discuss how photonics' primary role will be to provide interconnection between racks of electronic routing elements and describe how fast wavelength switching can provide a high-capacity distributed switch fabric that will allow these packet routers to scale to higher capacities. The fast wavelength switching can be seen as the packet analog of wavelength-based circuit switching of today's transparent optical networks.     

基于部分采样及混合分段的超高次谐波检测方法

高频电力电子设备的广泛应用导致电网中的超高次谐波问题日趋严重,而现有的谐波检测方法在用于检测频率范围更宽的超高次谐波时存在检测速度慢、处理数据多等问题,针对超高次谐波的检测缺乏统一且有效的标准。在全面剖析电力电子变流设备产生的超高次谐波频次特征与开关频率的关联性的基础上,提出一种基于特征频率分段的混合检测方法。通过部分采样FFT运算得到谐波峰值来确定开关频率,根据开关频率及其倍数频率附近的峰值特性自动确定频谱聚合的分段策略。仿真分析表明该方法在保障超高次谐波准确检测的基础上有效提升了检测速度,试验结果验证了方法的可行性和有效性,可为统一超高次谐波检测标准提供新思路。     

基于统一离散时域建模法的晶闸管串联运行暂态仿真

现有晶闸管仿真模型虽能较准确地模拟单只晶闸管开通和关断的动态过程,却较少涉及多只器件的串并联仿真。文中在分析晶闸管开关过程中动态特性的基础上,利用统一离散时域建模法建立了包含开关动态过程的晶闸管数学模型。由于该模型采用时变电阻来描述晶闸管工作过程中电压、电流的变化关系,因此适用于晶闸管串联电路的暂态仿真分析。仿真和实验结果表明所建立的晶闸管数学模型可较为准确地描述串联运行的晶闸管开关过程中电压的动态分配,从而为需晶闸管串联运行的大型电力电子装置的动静态均压电路设计提供了依据。     

Two silicon optical modulators realizable with a fully compatiblebipolar process

In this paper, we describe two different kinds of silicon optical modulators both integrated into a silicon on silicon optical channel waveguide which can be realized using a standard bipolar process. The possibility of using standard, well-known technology presents several advantages with respect to III-V optoelectronics. The first device presented is based on a three-terminal active device and exploits the plasma dispersion effect to achieve the desired modulation. The active device used is a bipolar mode field effect transistor; we show how the introduction of the third control terminal introduces some definite advantages with respect to commonly p-i-n driven modulators. The second is an electrically controlled Bragg reflector. In this case, although controlled by a p-i-n diode, fast switching speed is achieved. because lower injection levels are required. Numerical simulations and preliminary experimental results are presented on both devices     

GaN基功率电子器件及其应用专辑特邀主编述评

GaN基功率电子器件因其具有开关速度快、开关频率高、工作结温高、通态电阻小、开关损耗低等优势,适合应用于新型高效、大功率等的电力电子系统。国内关于GaN基功率电子器件的研究已经取得了较为明显的进展,但与发达国家相比仍有一定的差距。为此,《电源学报》特别推出了"GaN基功率电子器件及其应用"专辑,基本涵盖GaN功率电子器件及其应用研究的热点问题,展示了不同研究机构和企业在该领域的研发现状,具有良好的学术研究和应用参考价值。     

Efficient and realistic device modeling from atomic detail to the nanoscale

As semiconductor devices scale to new dimensions, the materials and designs become more dependent on atomic details. NEMO5 is a nanoelectronics modeling package designed for comprehending the critical multi-scale, multi-physics phenomena through efficient computational approaches and quantitatively modeling new generations of nanoelectronic devices as well as predicting novel device architectures and phenomena. This article seeks to provide updates on the current status of the tool and new functionality, including advances in quantum transport simulations and with materials such as metals, topological insulators, and piezoelectrics.     

The Modeling and Calculation of One Transistor Memory Devices

Metal/Ferroelectrics/Metal/Insulator/Si (MFMIS) and Metal/Ferroelectrics/ Insulator/Si (MFIS) one-transistor devices are being proposed for non-volatile memory applications. In order to determine the basic theory of one-transistor memory devices, we use equivalent circuits to model and calculate the basic properties of one-transistor memory devices. The capacitance of MFMIS and MFIS capacitors, memory windows, operation voltages, threshold voltages, and both switching and retention properties of one-transistor memory devices have also been calculated. According to the modeling and calculation, the ferroelectric materials with lower dielectric constant (?), low polarization (P_R), appropriate coercive field and square hysteresis loop are required for one-transistor memory devices and low voltage applications. High dielectric constant insulator materials may improve the performance of one-transistor memory devices. In addition, the effects of depolarization fields, leakage current, and defect density on the switching and retention properties of one-transistor memory devices are also calculated. Based on the modeling and calculation, the retention problem dealing with depolarization fields and leakage current is a big challenge for one-transistor memory devices.     

Physics-based modeling approaches of resistive switching devices for memory and in-memory computing applications

The semiconductor industry is currently challenged by the emergence of Internet of Things, Big data, and deep-learning techniques to enable object recognition and inference in portable computers. These revolutions demand new technologies for memory and computation going beyond the standard CMOS-based platform. In this scenario, resistive switching memory (RRAM) is extremely promising in the frame of storage technology, memory devices, and in-memory computing circuits, such as memristive logic or neuromorphic machines. To serve as enabling technology for these new fields, however, there is still a lack of industrial tools to predict the device behavior under certain operation schemes and to allow for optimization of the device properties based on materials and stack engineering. This work provides an overview of modeling approaches for RRAM simulation, at the level of technology computer aided design and high-level compact models for circuit simulations. Finite element method modeling, kinetic Monte Carlo models, and physics-based analytical models will be reviewed. The adaptation of modeling schemes to various RRAM concepts, such as filamentary switching and interface switching, will be discussed. Finally, application cases of compact modeling to simulate simple RRAM circuits for computing will be shown.     

Insulation coordination associated with distributed generation connected at distribution level

Insulation coordination is defined as the selection of dielectric strength of equipment, taking into account the over-voltages that could appear in the utility system and with the presence of protective devices. Electromagnetic transient (EMT) over-voltages are regarded as disturbances due to lightning surges and switching surges that result in the disruption and possible damage to equipments. The principal subject of this paper is to perform insulation coordination on the distributed generation (DG) by using methods of modeling lightning surges and switching surges. PSCAD/EMTDC is the main software used for the modeling and simulations.     

电力电子装置电磁兼容性的研究进展

电力电子装置的高频化和大容量化不仅导致器件所承受的电应力的增加和开关损耗的增加,而且产生难以抑制的宽带电磁干扰~［１－３］,对电网和环境造成严重的电磁污染,甚至威胁到其本身乃至与其相关的其他电子设备的正常工作。本文从电力电子装置的电磁干扰源产生的机理入手,概括了近年来国外的最新研究成果,并着重分析对比了硬开关与软开关的电磁干扰特性。     

一种采用状态变量反馈控制的三相正弦波PWM逆变器

讨论了一种采用状态变量反馈控制的三相正弦波逆变器，在较重的非线性负载下仍能保持负载输入端的波形较好。这种控制方式可以很容易地推广到其它电力电子装置的控制器中。提出了一种易于用计算机控制实现的脉宽调制（ＰＷＭ）开关控制模式，这种控制模式具有开关损耗较小的优点。     

SPICE modeling of nonlinear memristive behavior

The recent discovery of the ‘modern’ memristor has drawn great attention of both academia and industry. Given their favorable performance merits, memristors are expected to play a fundamental role in electronic industry. Modeling of memristive devices is essential for circuit design, and a number of Simulation Program with Integrated Circuit Emphasis (SPICE) models have already been introduced. The common problem in most models is that there is no threshold consideration; hence, only a few address the nonlinear nature of the device. This paper aims to present a SPICE implementation of a threshold‐type switching model of a voltage‐controlled memristive device that attributes the switching effect to a tunneling distance modulation. Threshold‐type switching is closer to the actual behavior of most experimentally realizable memristive systems, and our modeling approach addresses the issue of programming thresholds. Both the netlist and the simple schematic are provided, thus making it easy to comprehend and ready to be used. Compared with other modeling solutions, it involves significantly low‐complexity operation under an unlimited set of frequencies, and its simulation results are in good qualitative and quantitative agreement with the theoretical formulation. The proposed model is used to simulate an antiserial memristive switch, proving that it can be efficiently introduced in complex memristive circuits. Copyright © 2013 John Wiley & Sons, Ltd.