不同偏置影响锗硅异质结双极晶体管单粒子效应的三维数值仿真研究

针对国产锗硅异质结双极晶体管(SiGe HBT),采用半导体器件三维计算机模拟工具,建立单粒子效应三维损伤模型,研究不同偏置状态对SiGe HBT单粒子效应的影响.分析比较不同偏置下重离子入射器件后,各端口电流瞬变峰值和电荷收集量随时间的变化关系,获得SiGe HBT单粒子效应与偏置的响应关系.结果表明:不同端口对单粒子效应响应的最劣偏置不同,同一端口电荷收集量和瞬变电流峰值的最劣偏置也有所差异.载流子输运方式变化和外加电场影响是造成这种现象的主要原因.     

Phebalosin的全合成

以间苯二酚和D,L-苹果酸为原料,经Pechmann反应、Reimer-Tiemann反应、Darzens缩合反应及Wittig反应合成了Phebalosin,总收率1.3%,其结构经~1H NMR和~(13)C NMR表征.     

rGO/Ag0.005 Sn0.995 Se热电复合材料的制备及性能研究

为了实现石墨烯纳米相在基体中的均匀分散,提高多晶SnSe的热电性能,本文首先利用熔炼法合成了多晶Ag0.005 Sn0.995 Se材料,然后采用液相沉淀法实现了Ag0.005 Sn0.995 Se与氧化石墨烯(GO)均匀复合,再经过氢气还原和SPS烧结制备得到rGO/Ag0.005 Sn0.995 Se复合材料.研究结果表明,复合rGO显著提高了载流子迁移率,电导率由基体的33.64 S/cm提高到39.29 S/cm.同时第二相rGO的引入,增加了晶界数量,增强了声子散射,降低了热导率.当复合rGO量为0.50wt; 时,在垂直热压方向上获得了最高的ZT值0.73(773 K).     

若干镍(Ⅱ)、铜(Ⅱ)的平面型配合物对丙烯氧化反应的催化作用

本文报道若干平面四方多酮配合物对丙烯氧化反应的催化作用。指出Ni(Ⅱ)平面四方配合物可以利用其轴向的配位空穴活化烯键。     

Uniaxial stress influence on lattice, band gap and optical properties of n-type ZnO:first-principles calculations

The lattice, the band gap and the optical properties of n-type ZnO under uniaxial stress are investigated by first-principles calculations. The results show that the lattice constants change linearly with stress. Band gaps are broadened linearly as the uniaxial compressive stress increases. The change of band gap for n-type ZnO comes mainly from the contribution of stress in the c-axis direction, and the reason for band gap of n-type ZnO changing with stress is also explained. The calculated results of optical properties reveal that the imaginary part of the dielectric function decreases with the increase of uniaxial compressive stress at low energy. However, when the energy is higher than 4.0 eV, the imaginary part of the dielectric function increases with the increase of stress and a blueshift appears. There are two peaks in the absorption spectrum in an energy range of 4.0-13.0 eV. The stress coefficient of the band gap of n-type ZnO is larger than that of pure ZnO, which supplies the theoretical reference value for the modulation of the band gap of doped ZnO.     

Three-dimensional simulation of fabrication process-dependent effects on single event effects of SiGe heterojunction bipolar transistor

The fabrication process dependent effects on single event effects(SEEs) are investigated in a commercial silicon–germanium heterojunction bipolar transistor(SiGe HBT) using three-dimensional(3D) TCAD simulations. The influences of device structure and doping concentration on SEEs are discussed via analysis of current transient and charge collection induced by ions strike. The results show that the SEEs representation of current transient is different from representation of the charge collection for the same process parameters. To be specific, the area of C/S junction is the key parameter that affects charge collection of SEE. Both current transient and charge collection are dependent on the doping of collector and substrate. The base doping slightly influences transient currents of base, emitter, and collector terminals. However, the SEEs of SiGe HBT are hardly affected by the doping of epitaxial base and the content of Ge.     

新型锕填充硼碳笼型化合物的超导电性

Ac元素作为锕系第一号元素,AcH₁₀的超导转变温度(T_c)达到251 K,是潜在的室温超导体。XB₃C₃(X表示不同的金属掺杂元素)是新发现的sp³笼型化合物,同时具有强共价特性和超导特性,是潜在的高温超导材料。采用第一性原理密度泛函理论,探索以XB₃C₃、XB₂C₄和XB₄C₂笼型结构为原型、引入Ac元素掺杂的AcB₃C₃、AcB₂C₄和AcB₄C₂的晶体结构、晶格动力学、电子性质和超导特性。研究发现:AcB₂C₄在0～200 GPa区间内难以合成;常压下AcB₃C₃表现为间接带隙半导体,带隙宽度约为1.154 eV。根据力学稳...     

新课程下高中生化学学习成就动机水平的现状调查

结合学科特点,对AMS进行修订,用编制的《高中生化学学习成就动机水平现状调查问卷》并结合访谈,对重庆市4所重点中学高中生的化学学习成就动机水平现状进行调查。结果表明:新课程改革下,高中生的化学学习成就动机处于中等偏高水平,不同性别和学业水平的学生均存在显著差异。学生在面对评价自身能力的化学学习任务时,追求成功的动机最强,避免失败的动机最弱;在面对不确定的化学学习任务时,避免失败的动机最强,追求成功的动机最弱。与解答化学试题相比,学生在面对化学实验和科学探究活动时成就动机水平较高。研究结果为激发和训练高中生化学学习成就动机提供了启示。     

高耸塔台结构抗风实验研究

本文对首都机场新塔台结构的刚性模型和气动弹性模型进行了风洞试验研究。提出了考虑弗劳德数等一系列相似参数模拟的高耸塔台结构气动弹性模型的设计制作方法。获得了高耸塔台结构的风压分布规律及加速度风振响应特性。     

高效液相色谱-蒸发光散射法测定食品中的单糖、双糖、低聚果糖和糖醇

建立了食品中常用的木糖、果糖、葡萄糖、蔗糖、麦芽糖、乳糖、蔗果三糖、蔗果四糖、蔗果五糖、赤藓糖醇、木糖醇、甘露糖醇、麦芽糖醇等13种单糖、双糖、低聚果糖和糖醇的高效液相色谱同时分离检测的方法。该法采用NH₂色谱柱,以乙腈-水为流动相梯度洗脱,蒸发光散射检测器检测;13种糖在0.1~5 g/L内均具有良好的线性关系,检出限均在0.1 g/L以下,精密度(RSD)为2.69%~7.21%,回收率为96.1%~105.2%,结果较为理想。将该法用于实际样品检测,结果显示食品标签明示和实际成分相差较大。