电子器件散粒噪声测试方法研究

本文分析了超导量子干涉器(SQUID)和超导-绝缘-超导(SIS)约瑟夫森结散粒噪声测试方法的应用局限性,提出了常规器件的散粒噪声测试方案.针对常规电子器件散粒噪声特性,研究了噪声测试基本条件,并建立了低温测试系统.通过采用双层屏蔽结构和超低噪声前置放大器,实现了较好的电磁干扰屏蔽和极低的背景噪声.在10 K温度下对常规二极管散粒噪声进行了测试,通过理论和测试结果对比分析,验证了测试系统的准确和可信性. 关键词： 散粒噪声 电子器件 噪声测试     

崖县风车子茎化学成分研究

研究崖县风车子茎的化学成分。用硅胶柱层析法、制备薄层色谱法、重结晶法和高效液相色谱法进行分离,并根据理化性质和光谱数据对分离化合物进行结构鉴定。分离并鉴定了10个化合物,分别为:3,3',4'-tri-O-methylellagic acid(1),3,3'-di-O-methylellagic acid(2),hederagenin(3),白桦脂酸(4),6R,9R-blumenol B(5),6S,9R-blumenol B(6),2α,3β,23-trihydroxyolean-12-en-28-oic(7),4-hydroxycinnamic acid(8),咖啡酸(9),evofolin B(10)。化合物5、6、9和10为首次从该属植物中分离得到,所有化合物均为首次从该植物中分离得到。     

海南染木树叶中的蒽醌成分研究

从海南染木树叶乙醇提取物的乙酸乙酯萃取部位分离得到9个蒽醌类化合物,采用高分辨质谱、一维和二维核磁共振等现代波谱技术,鉴定上述化合物的结构分别为:7-羟基-1,2-二甲氧基-6-甲基-9,10-蒽醌(1),1-羟基-3,6-二甲氧基-9,10-蒽醌(2),10,10'-二蒽酮(3),9,10-蒽醌(4),甲基异茜草素(5),虎刺醇(6),2-羟基-3-甲基-9,10-蒽醌(7),3-羟基-1,2-二甲氧基-9,10-蒽醌(8)和3-羟基-1-甲氧基-2-甲酯基-9,10-蒽醌(9).其中化合物1和2为新天然产物,且化合物1的波谱数据迄今未见任何报道.除化合物9外,其余化合物均为首次从该属植物中分离得到.抗菌活性测试显示,化合物2和9对多种菌株具有很好的抑制作用,尤其是金黄色葡萄球菌,最小抑菌浓度(MIC)值均达到0.078μg/mL;化合物1和6对枯草芽孢杆菌、金黄色葡萄球菌显示出与阳性对照环丙沙星相当或者更强的抑制活性.     

环糊精手性分离固定相在手性药物的液相色谱和毛细管柱电色谱分析中应用的研究进展

对环糊精手性分离固定相在手性药物的液相色谱和毛细管电色谱法分析中应用的近期研究进展(主要从2008年1月至2013年7月间)情况进行综述。内容主要涉及此类固定相的合成方法,选择性功能基团的固定以及新型环糊精手性分离固定相在液相色谱及毛细管电色谱等方面的应用情况,并对其发展前景作了简述(引用文献49篇)。     

提高分析化学课堂吸引力的教学策略

课堂是老师和学生交流的主要场所,在高校分析化学的课堂教学中,教师可以从转换专注与发散2种学习模式、合理利用图形背景原则、课堂执行Chunk学习法、提倡课堂高效自主学习及开展课堂讨论、自主完形闭合等几个方面入手,让学生成为分析化学课堂的主人翁,真正吸引他们投身其中。     

A theoretical extraction scheme of transport information based on exclusion models

In order to explore how to extract more transport information from current fluctuation,a theoretical extraction scheme is presented in a single barrier structure based on exclusion models,which include counter-flows model and tunnel model.The first four cumulants of these two exclusion models are computed in a single barrier structure,and their characteristics are obtained.A scheme with the help of the first three cumulants is devised to check a transport process to follow the counter-flows model,the tunnel model or neither of them.Time series generated by Monte Carlo techniques is adopted to validate the abstraction procedure,and the result is reasonable.     

金属互连电迁移噪声的非高斯性模型研究

根据电子散射理论,多晶互连中,电阻主要起源于晶界处空位与空洞对电子的散射作用.通过引入自由体积的概念,模拟了晶界处电子的散射过程,建立了基于自由体积的噪声非高斯性表征模型.该模型表明,电迁移前期的噪声信号以高斯噪声为主,随电迁移过程将发生噪声信号从高斯性向非高斯性的突变,表明噪声产生机制发生了转变,并通过双相干系数对信号的非高斯性进行了定量表征.最终,通过实验初步证明了理论结果的正确性.     

Temperature-dependent characteristics of 4H-SiC junction barrier Schottky diodes

The current-voltage characteristics of 4H-SiC junction barrier Schottky(JBS) diodes terminated by an offset field plate have been measured in the temperature range of 25-300 C.An experimental barrier height value of about 0.5 eV is obtained for the Ti/4H-SiC JBS diodes at room temperature.A decrease in the experimental barrier height and an increase in the ideality factor with decreasing temperature are shown.Reverse recovery testing also shows the temperature dependence of the peak recovery current density and the reverse recovery time.Finally,a discussion of reducing the reverse recovery time is presented.     

Monte Carlo study of single-barrier structure based on exclusion model full counting statistics

Different from the usual full counting statistics theoretical work that focuses on the higher order cumulants computation by using cumulant generating function in electrical structures, Monte Carlo simulation of single-barrier structure is performed to obtain time series for two types of widely applicable exclusion models, counter-flows model, and tunnel model. With high-order spectrum analysis of Matlab, the validation of Monte Carlo methods is shown through the extracted first four cumulants from the time series, which are in agreement with those from cumulant generating function. After the comparison between the counter-flows model and the tunnel model in a single barrier structure, it is found that the essential difference between them consists in the strictly holding of Pauli principle in the former and in the statistical consideration of Pauli principle in the latter.