Supply voltage scaled dependency of the recovery of single event upset in advanced complementary metal-oxide-semiconductor static random-access memory cells

Using the technology computer-aided design three-dimensional simulation, the supply voltage scaled dependency of the recovery of single event upset and charge collection in static random-access memory cells are investigated. It reveals that the recovery linear energy transfer threshold decreases with the supply voltage reducing, which is quite attractive to the dynamic voltage scaling and subthreshold circuits radiation-hardened design. Additionally, the effect of supply voltage on charge collection is also investigated. It is concluded that the supply voltage mainly affects the bipolar gain of parasitical bipolar junction transistor (BJT) and the existence of the source plays an important role in the supply voltage variation.     

The modulation effect of substrate doping on multi-node charge collection and single-event transient propagation in 90-nm bulk complementary metal-oxide semiconductor technology

Variation of substrate background doping will affect the charge collection of active and passive MOSFETs in complementary metal-oxide semiconductor (CMOS) technologies, which are significant for charge sharing, thus affecting the propagated single event transient pulsewidths in circuits. The trends of charge collected by the drain of a positive channel metal-oxide semiconductor (PMOS) and an N metal-oxide semiconductor (NMOS) are opposite as the substrate doping increases. The PMOS source will inject carriers after strike and the amount of charge injected will increase as the substrate doping increases, whereas the source of the NMOS will mainly collect carriers and the source of the NMOS can also inject electrons when the substrate doping is light enough. Additionally, it indicates that substrate doping mainly affects the bipolar amplification component of a single-event transient current, and has little effect on the drift and diffusion. The change in substrate doping has a much greater effect on PMOS than on NMOS.     

Temperature and drain bias dependence of single event transient in 25-nm FinFET technology

In this paper,we investigate the temperature and drain bias dependency of single event transient(SET) in 25-nm fin field-effect-transistor(FinFET) technology in a temperature range of 0-135°C and supply voltage range of 0.4 V-1.6 V.Technology computer-aided design(TCAD) three-dimensional simulation results show that the drain current pulse duration increases from 0.6 ns to 3.4 ns when the temperature increases from 0 to 135°C.The charge collected increases from 45.5 fC to 436.9 fC and the voltage pulse width decreases from 0.54 ns to 0.18 ns when supply voltage increases from 0.4 V to 1.6 V.Furthermore,simulation results and the mechanism of temperature and bias dependency are discussed.     

Polar Dependence of Threading Dislocation Density in GaN Films Grown by Metal-Organic Chemical Vapor Deposition

We investigate the threading dislocation(TD) density in N-polar and Ga-polar GaN films grown on sapphire substrates by metal-organic chemical vapor deposition.X-ray diffraction results reveal that the proportion of screw type TDs in N-polar GaN is much larger and the proportion of edge type TDs is much smaller than that in Ga-polar.Transmission electron microscope results show that the interface between the AlN nucleation layer and the GaN layer in N-polar films is smoother than that in Ga-polar films,which suggests different growth modes of GaN.This observation explains the encountered difference in screw and edge TD density.A model is proposed to explain this phenomenon.     

空间激光通信最新进展与发展趋势

空间激光通信凭借其带宽优势,成为未来高速空间通信不可或缺的有效手段,是近年来国际上的研究热点。本文详细介绍了美国、欧洲和日本在空间激光通信技术领域的最新研究进展和未来发展规划,总结了国内外空间激光通信演示计划的主要参数指标。通过对空间激光通信最新研究计划的分析,归纳出空间激光通信高速化、深空化、集成化、网络化、一体化5个发展趋势,以及需要突破的高阶调制、高灵敏度探测、多制式兼容、"一对多"通信等关键技术。为我国激光通信设备及相关研究提供借鉴和参考。     

单晶金刚石氢终端场效应晶体管特性

基于微波等离子体化学气相淀积生长的单晶金刚石制作了栅长为2μm的耗尽型氢终端金刚石场效应晶体管,并对器件特性进行了分析.器件的饱和漏电流在栅压为-6 V时达到了96 mA/mm,但是在-6 V时栅泄漏电流过大.在-3.5 V的安全工作栅压下,饱和漏电流达到了77 mA/mm.在器件的饱和区,宽5.9 V的栅电压范围内,跨导随着栅电压的增加而近线性增大到30 mS/mm.通过对器件导通电阻和电容-电压特性的分析,氢终端单晶金刚石的二维空穴气浓度达到了1.99×10~(13)cm~(-2),并且迁移率和载流子浓度均随着栅压向正偏方向的移动而逐渐增大.分析认为,沟道中高密度的载流子、大的栅电容以及迁移率的逐渐增加是引起跨导在很大的栅压范围内近线性增加的原因.     

基于区域特色和专业特点的药学分析化学课程改革

为培养更加符合区域特色的应用型药学人才,通过加强基础知识和基本技能的培训、更换实验教学内容、改变理论教学方式、针对不同专业采用不同模块化教学的方式,对分析化学开展全方位的课程改革。经调查,本次课程改革教学效果、学生学习兴趣、创新能力明显提高。     

两个四唑配合物的原位合成、多样化配位模式和强荧光性质

在路易斯酸ZnCl₂或MnSO₄·7H₂O作用下,通过1-甲基-1-氢-咪唑-4,5-二甲腈与NaN₃水热原位合成了2个四唑配合物：{[Zn₂（midt）（Hmidt）]（N₃）·H₂O}_n （1）和[Mn（midt）₂·（H₂O）₂]·H₂O （2）（midt=1-甲基-1-氢-咪唑-4,5-二四唑）。X射线单晶衍射表明尽管配合物1和2均结晶于同样的P1 空间群,但他们有完全不同的结构。配合物1为一个有趣的二维聚合物结构,含有两个不同配位环境的锌原子和多种配位模式的midt配体,而配合物2为一个三维超分子结构,包含一个有趣的水分子链结构。固态下1和2分别在353和382 nm处显示出较强的蓝色荧光。     

用于目标跟踪/识别中红外AOTF光谱相机光学系统的设计与优化

为获得红外目标的空间信息和光谱信息,设计了一种用于中波红外声光可调谐光谱相机的光学系统.设计中引入折/衍射混合透镜,在用6片透镜的情况下达到了12×变倍,在长焦处时能识别2 000m远的目标.采用ZEMAX光学设计软件模拟声光晶体的衍射,在晶体出射面上优化设计了4°的楔角,使-1级衍射光能共轴出射.该光学系统在空间频率17lp/mm处调制传递函数值最大达到0.7,能量集中度大于90%,能够满足光谱相机用于识别/跟踪目标的要求.     

Improvement in a-plane GaN crystalline quality using wet etching method

Nonpolar （1120） GaN films are grown on the etched a-plane GaN substrates via metalorganic vapor phase epitaxy. High-resolution X-ray diffraction analysis shows great decreases in the full width at half maximum of the samples grown on etched substrates compared with those of the sample without etching, both on-axis and off-axis, indicating the reduced dislocation densities and improved crystalline quality of these samples. The spatial mapping of the E2 （high） phonon mode demonstrates the smaller line width with a black background in the wing region, which testifies the reduced dislocation densities and enhanced crystalline quality of the epitaxial lateral overgrowth areas. Raman scattering spectra of the E2 （high） peaks exhibit in-plane compressive stress for all the overgrowth samples, and the E2 （high） peaks of samples grown on etched substrates shift toward the lower frequency range, indicating the relaxations of in-plane stress in these GaN films. Furthermore, room temperature photoluminescence measurement demonstrates a significant decrease in the yellow-band emission intensity of a-plane GaN grown on etched templates, which also illustrates the better optical properties of these samples.