Quantitative Analysis of the Degradation Behavior of Silicon Solar Cell Irradiated by 1 MeV Electron Beams Using Photocarrier Radiometry Combined with Lock-in Carrierography

Silicon solar cells with cover glass irradiated by 1 MeV electron beams at various fluences were investigated using photocarrier radiometry (PCR) combined with lock-in carrierography (LIC, spectrally gated dynamic photoluminescence). The minority carrier transport properties (i.e., minority carrier lifetime τ, diffusion coefficient D, surface recombination velocities S) and the degradation of these properties were studied using PCR. The relative damage coefficient obtained by LIC was consistent with the PCR measurement. The local series resistance of the solar cell before and after irradiation was characterized by LIC. The results showed that the series resistance increased with electron fluences.     

Reliability Modeling for Ultrathin Gate Oxides Subject to Logistic Degradation Processes with Random Onset Time

With device dimension downscaling, the oxide thickness reduction less than 3 nm in a metal–oxide–semiconductor structure has led to important changes in degradation mechanisms and failure modes. After the first breakdown event of ultrathin gate oxides, the leakage current presents a less dramatic and noisy continuous breakdown mode called progressive breakdown. In this article, we characterize the overall breakdown process of ultrathin gate oxides as a randomized logistic degradation process with a random onset time. The explicit result of the lifetime distribution is derived on the basis of this logistic degradation model. A numerical example is provided to calculate the lifetime distribution. The simulated lifetime data of our model fits lognormal distribution better than the Weibull distribution, which agrees with the experimental work in literature. Copyright © 2012 John Wiley & Sons, Ltd.     

High Phase Purity of Large‐Sized 1T′‐MoS2 Monolayers with 2D Superconductivity

The development of transition metal dichalcogenides has greatly accelerated research in the 2D realm, especially for layered MoS₂. Crucially, the metallic MoS₂ monolayer is an ideal platform in which novel topological electronic states can emerge and also exhibits excellent energy conversion and storage properties. However, as its intrinsic metallic phase, little is known about the nature of 2D 1T′‐MoS₂, probably because of limited phase uniformity (<80%) and lateral size (usually <1 µm) in produced materials. Herein, solution processing to realize high phase‐purity 1T′‐MoS₂ monolayers with large lateral size is demonstrated. Direct chemical exfoliation of millimeter‐sized 1T′ crystal is introduced to successfully produce a high‐yield of 1T′‐MoS₂ monolayers with over 97% phase purity and unprecedentedly large size up to tens of micrometers. Furthermore, the large‐sized and high‐quality 1T′‐MoS₂ nanosheets exhibit clear intrinsic superconductivity among all thicknesses down to monolayer, accompanied by a slow drop of transition temperature from 6.1 to 3.0 K. Prominently, unconventional superconducting behavior with upper critical field far beyond the Pauli limit is observed in the centrosymmetric 1T′‐MoS₂ structure. The results open up an ideal approach to explore the properties of 2D metastable polymorphic materials.     

高流动性星型尼龙12的合成与表征

在均苯三甲酸的存在下,进行十二内酰胺的水解聚合,合成了四种不同臂长的三臂星型尼龙12,对产物的分子量进行了测定,并对其力学性能和流变行为进行了研究。结果表明,星型尼龙12的分子量随着均苯三甲酸含量的提高而降低,与相应分子量的线型尼龙12相比,星型尼龙12的拉伸强度和弯曲强度基本保持,冲击强度保持率在80%以上,断裂伸长...     

水稻基因组MSAP指纹图谱构建及DNA甲基化修饰位点分离与鉴定

采用EcoR I和Hpa II/Msp I双酶切建立了适合于水稻基因组的甲基化敏感扩增多态性(MSAP)分析体系,在全基因组水平检测了水稻DNA甲基化修饰位点.以12对MSAP引物进行选择性扩增,共检测到甲基化修饰位点120个,"CCGG/GGCC"位点甲基化修饰比例为20.17%.对部分水稻基因组甲基化修饰位点进行回收,最终分离了55条存在甲基化位点变异的DNA序列,通过BLAST比对分析将其联配到水稻基因组序列上.分析表明,这些甲基化修饰位点主要集中于基因启动子区(47%)和第一外显子区(22%),在其侧翼序列中存在类似"CpG island" 典型序列特征的"CpG"二核苷酸成簇富集区.在此基础上,对应用MSAP技术分离水稻基因组DNA甲基化修饰位点的有效性以及水稻基因组序列中"CpG island"类似序列分布特征和生物意义进行了讨论.     

全层片状TiAl基合金断裂过程的原位观察

利用ＳＥＭ拉伸台，研究了Ｔｉ－３３Ａｌ－３Ｃｒ－０．５Ｍｏ合金的室温拉伸断裂动态过程。试验结果表明，具有全层片状显微组织的ＴｉＡｌ合金室温断裂韧性较高，归因于合金拉伸过程中裂纹尖端发生分叉致使应力松弛而使裂纹钝化；在变形过程中，主裂纹尖端附近的微裂纹之间形成剪切韧带，剪切韧带韧化是ＴｉＡｌ合金的一种韧化机理。     

A Bifunctional-Modulated Conformal Li/Mn-Rich Layered Cathode for Fast-Charging,High Volumetric Density and Durable Li-Ion Full Cells

Lithium- and manganese-rich (LMR) layered cath-ode materials hold the great promise in designing the next-genera-tion high energy density lithium ion batteries....