Space Charge Observation in Aramid/Epoxy Insulations Under DC Electric Fields

With the progress of printed circuit technology, the reliability of bulk insulation has become important, as well as that of surface insulation, particularly in multilayer boards and embedded boards. We observed the space charge behavior of various insulating materials used in printed circuit boards, and found that internal charges move in aramid/epoxy specimens under dc electric fields. The electric field near the surface of the specimen, therefore, was increased to have more than twice the strength of the average applied field. The space charge profile was influenced by the internal structure, and its formation was accelerated by the increase of temperature. Since the space charge profile affects the internal electric field distribution, the internal charge behavior should be examined with respect to the design of the insulation of a printed circuit board.     

一种用于分离pMOS器件热载流子应力下氧化层陷阱电荷和界面陷阱电荷对阈值电压退化作用的方法

在电荷泵技术的基础上,提出了一种新的方法用于分离和确定氧化层陷阱电荷和界面陷阱电荷对pMOS器件热载流子应力下的阈值电压退化的作用,并且这种方法得到了实验的验证.结果表明对于pMOS器件退化存在三种机制:电子陷阱俘获、空穴陷阱俘获和界面陷阱产生.需要注意的是界面陷阱产生仍然是pMOS器件热载流子退化的主要机制,不过氧化层陷阱电荷的作用也不可忽视.     

空间电荷波传播特性的PIC粒子模拟

采用周期性边界条件的二维准静电PIC粒子模拟程序对空间电荷波的产生及传播过程进行了数值模拟,给出了静止和一维定向漂移空间电荷波的产生及传播特性随等离子体参数变化的关系,通过单电子跟踪的方法,得到了波动过程带电粒子的空间状态的变化规律。其结果,将作为进一步实现空间电荷波与电磁波产生波一波相互作用过程模拟的基础。     

一种用于分离pMOS器件热载流子应力下氧化层陷阱电荷和界面陷阱电荷对阈值电压退化作用的方法

在电荷泵技术的基础上,提出了一种新的方法用于分离和确定氧化层陷阱电荷和界面陷阱电荷对p MOS器件热载流子应力下的阈值电压退化的作用,并且这种方法得到了实验的验证.结果表明对于p MOS器件退化存在三种机制:电子陷阱俘获、空穴陷阱俘获和界面陷阱产生.需要注意的是界面陷阱产生仍然是p MOS器件热载流子退化的主要机制,不过氧化层陷阱电荷的作用也不可忽视.     

一种求解连续空间优化问题的动态蚁群算法

在实现了连续蚁群算法的基础上,针对蚁群算法容易陷入局部最优解的问题,对连续蚁群算法的全局转移概率进行改进,提出一种动态蚁群算法(DACO),根据动态全局转移概率分配蚂蚁个数,进行不同阶段的搜索.仿真实验表明,动态蚁群算法能够得到更精确的解.     

Dynamic Turn-On Mechanism of the n-MOSFET Under High-Current Stress

In this letter, the dynamic turn-on mechanism of the n-MOSFET under high-current-stress event is investigated by using a real-time current and voltage measurement. Results reveal the existence of ldquoself-consistent effect,rdquo i.e., the turn-on region of the parasitic n-p-n bipolar can change from one region to another region and increases with the stress current (ID). Furthermore, experimental data show that the minimum substrate potential to sustain a stable snapback phenomenon is 0.9 V and increases with ID instead of 0.6-0.8 V and independent of ID as reported in early literatures.     

Improved Stability of Pd/Ti Contacts to <Emphasis Type="Italic">p</Emphasis>-Type SiC Under Continuous DC and Pulsed DC Current Stress

The enhanced stability of Pd/Ti contacts to p-type SiC under high-current-density continuous direct-current (DC) stressing is investigated and compared with previous work on Ti/Al contacts. Additionally, differing failure modes were observed for the Pd/Ti contacts under continuous DC and pulsed DC stress. The improved stability of the Pd/Ti contacts is demonstrated through a 29% increase in the applied continuous DC current required to cause electrical failure during a 1 h test compared with the Ti/Al contacts. The metallization scheme includes a TiW barrier and a thick electroplated Au overlayer. While severe intermixing and voiding in the ohmic contact layer caused the Pd/Ti contacts to fail under continuous DC stress, electromigration of the Au overlayer degraded the contacts under pulsed DC stress. The temperature of the surface of the contacts was reduced from over 649°C for contacts that failed under continuous DC current to between 316°C and 371°C for pulsed DC current. The difference in temperature and failure modes of the continuous and pulsed DC stressed contacts indicates different failure mechanisms.     

深空动态场景目标红外图像仿真研究

针对深空背景空间目标的红外图像仿真问题,首先根据热平衡理论,对典型空间目标进行建模,得到目标不同部分的温度;然后建立目标的红外辐射模型,得到目标的红外辐射光谱特性;接着提出了一种基于红外星表数据库的星空背景建模方法,模拟任意时刻,任意视场大小和指向的红外星空背景;最后得到了不同距离、不同姿态空间目标与深空背景合成的红外图像仿真序列,实现了探测器不断接近目标过程中的红外辐射图像仿真.     

高鲁棒性N型沟道RF-LDMOS在TLP应力下的电学机理研究

提高射频功率器件的鲁棒性有利于增强器件的抗静电放电能力和抗失配能力.为了直观地了解器件内部发生的电学过程,本文研究了高鲁棒性N型沟道RF-LDMOS（Radio Frequency Lateral Diffusion MOS）在TLP（Transmission Line Pulse）应力下的电学机理.利用0.18μm BCD（Bipolar/CMOS/DMOS）先进制程,实现了特定尺寸器件的设计与流片.通过实测与仿真的对比,发现静电放电失效的随机性、芯片内部的热效应是导致仿真和实测差异的非理想因素.通过对TLP仿真的各阶段重要节点的分析,证明了源极下方的P型埋层有利于提高空穴电流的泄放能力,从而提高RF-LDMOS的鲁棒性.     

Dynamic Characterstics of the Push-Pull DC to DC Converter

The dynamic characteristics of the push-pull dc to dc converter are analyzed both theoretically and experimentally for the modes of operation which are caused by the interaction between magnetizing current of the transformer and that of the reactor. Among all six modes of operation, four modes are of the first-order system. In two out of the four modes, the instantaneous reactor current does not fall to zero at any point in the switching cycle.     

Stability of Amorphous-Silicon and Nanocrystalline Silicon Thin-Film Transistors Under DC and AC Stress

Bottom-gated n-channel thin-film transistors (TFTs) were fabricated using hydrogenated amorphous-silicon (a-Si:H)/ nanocrystalline silicon (nc-Si:H) bilayers as channel materials, which are deposited by plasma-enhanced chemical vapor deposition at low temperatures. The stability of these devices is investigated under static and dynamic bias stress conditions. For comparison, the stability of a-Si:H and nc-Si:H single-layer TFTs is investigated under similar bias stress conditions. The overall results demonstrate that the a-Si:H/nc-Si:H bilayer TFTs are superior compared with their counterparts of a-Si:H and nc-Si:H TFTs regarding device performance and stability.     

Al/SRO/Si结构中横向电压作用下的电荷俘获效应

利用Al/ SRO/ Si MOS,对富硅二氧化硅(SRO)材料在横向电压作用下的电荷俘获效应进行了研究.用L PCVD法在n型Si衬底上沉积SRO材料,通过C- V测量研究其电荷俘获性质.发现对于n型Si衬底,在横向电压作用下,SRO层能够俘获正电荷,电荷俘获效应与SRO层的性质有关.基于电位在器件内部的分布及诱导pn结的形成,提出了一个简单的物理模型来解释所得到的实验结果     

Al/SRO/Si结构中横向电压作用下的电荷俘获效应

利用Al/SRO/Si MOS,对富硅二氧化硅(SRO)材料在横向电压作用下的电荷俘获效应进行了研究.用LPCVD法在n型Si衬底上沉积SRO材料,通过C-V测量研究其电荷俘获性质.发现对于n型Si衬底,在横向电压作用下,SRO层能够俘获正电荷,电荷俘获效应与SRO层的性质有关.基于电位在器件内部的分布及诱导pn结的形成,提出了一个简单的物理模型来解释所得到的实验结果.     

Kinetics of Space Charge Storage in Composites

Composites of ion and electron conducting phases allow for interfacial storage of a neutral component via space charge effects. The present contribution considers the rate of transport‐controlled incorporation and excorporation in such artificial mixed conductors. The upper limit of the relaxation time is determined by interfacial job‐sharing diffusion which is analyzed in greater detail. In general cases bulk phases assist by migration processes (dual phase transport). For more complex morphological situations, the considerations are complemented by numerical calculations. Thus the treatment also offers a pertinent approach with respect to the kinetics of solid state supercapacitors. Selected experimental results are included in the discussion.     

TLP应力下深亚微米GGNMOSFET特性的仿真

对TLP(传输线脉冲)应力下深亚微米GGNMOS器件的特性和失效机理进行了仿真研究. 分析表明，在TLP应力下，栅串接电阻减小了保护结构漏端的峰值电压；栅漏交迭区电容的存在使得脉冲上升沿加强了栅漏交叠区的电场，栅氧化层电场随着TLP应力的上升沿减小而不断增大，这会导致栅氧化层的提前击穿. 仿真显示，栅漏交迭区的电容和栅串接电阻对GGNMOS保护器件的开启特性和ESD耐压的影响是巨大的. 该工作为以后的TLP测试和标准化提供了依据和参考.     

TLP应力下深亚微米GGNMOSFET特性的仿真

对TLP(传输线脉冲)应力下深亚微米GGNMOS器件的特性和失效机理进行了仿真研究.分析表明,在TLP应力下,栅串接电阻减小了保护结构漏端的峰值电压;栅漏交迭区电容的存在使得脉冲上升沿加强了栅漏交叠区的电场,栅氧化层电场随着TLP应力的上升沿减小而不断增大,这会导致栅氧化层的提前击穿.仿真显示,栅漏交迭区的电容和栅串接电阻对GGNMOS保护器件的开启特性和ESD耐压的影响是巨大的.该工作为以后的TLP测试和标准化提供了依据和参考.     

空间相机连续调焦地面仿真测试系统设计

为使空间相机获得清晰准确的地面目标图像,相机需要依据结构变化对焦面位置进行调整。如果空间相机可以在轨快速对目标景物连续调焦,通过地面下传图像准确判断出最优焦面位置,将会极大提高空间相机的工作质量和效率。为验证连续调焦方法的可行性,提出了一种地面仿真测试方法。采用动态目标发生器和平行光管模拟相机在轨对地面目标成像。应用计算机系统作为目标发生器远程控制、数据处理、信息发送和接收设备,空间相机实时接收飞行器模拟设备发送的命令和工程参数,完成模拟在轨连续调焦。试验结果表明,所设计的系统能够依据图像判断最优焦面位置,满足设计和测试要求。     

考虑空间电荷效应时速调管射频间隙耦合系数的理论与模拟

在大功率速调管中,由于电子注电流较大,间隙距离较长,在间隙中由电子群聚产生的交流空间电荷效应不可忽略。根据传统的运动学理论来计算速调管间隙耦合系数,并没有考虑这个效应,计算的结果高于实际值。该文利用Webster去聚理论,建立了在任意间隙场分布情况下,考虑空间电荷效应的间隙耦合系数计算模型。利用粒子模拟工具,进行了仿真模拟,理论计算与仿真结果一致。