Performance improvement in pentacene organic thin film transistors by inserting a C60 ultrathin layer

The contact effect on the performances of organic thin film transistors is studied here. A C₆₀ ultrathin layer is inserted between Al source--drain electrode and pentacene to reduce the contact resistance. By a 3 nm C₆₀ modification, the injection barrier is lowered and the contact resistance is reduced. Thus, the field-effect mobility increases from 0.12 to 0.52 cm²/(V·s). It means that inserting a C₆₀ ultra thin layer is a good method to improve the organic thin film transistor (OTFT) performance. The output curve is simulated by using a charge drift model. Considering the contact effect, the field effect mobility is improved to 1.15 cm²/(V·s). It indicates that further reducing the contact resistance of OTFTs should be carried out.     

光学元件库--欧普特科技

北京欧普特公司参照国际通常规格及技术指标,备有完整系列的精密光学零部件(备有产品样本供参考) ,供国内各大专院校、科研机构、实验室随时选用,公司同时可为用户提供技术咨询.光学透镜:平凸、双凸,平凹,双凹,消色差胶合透镜等.直径 1～15 0mm ;焦距1～10 0 0mm ;材料包括光学玻璃,紫外石英玻璃,有色光学玻璃,红外材料.光学棱镜:1～5 0mm各种规格直角棱镜,及其他常用棱镜.光学反射镜:各种尺寸规格的镀铝,镀银,镀金,及介质反射镜.直径 5～2 0 0mm .光学窗口:各种尺寸规格、材料的光学平面窗口,平晶.直径 5～2 0 0mm .各种有色玻璃滤光片:规…     

Lagrangian Structure Function＇s Scaling Exponents in Turbulent Channel Flow

The Lagrangian structure function＇s scaling exponents and intermittency of three-dimensional incompressible turbulent channel flow are investigated by using direct numerical simulation. The intermittency in streamwise velocity increments is found to increase in the near-wall region, which can be attributed to the presence of strong mean shear and organized motions in the near-wall region. It is found that the intermittency of transverse velocity increments is weaker than that of longitudinal ones. The present ESS evaluation of ζL（q） for the structure function of the streamwise velocity component in the channel centre is fairly close to experimental estimates of isotropic turbulence.     

Infrared Absorption Spectra of Undoped and Doped Few-Layer Graphenes

The infrared absorption spectra of undoped few-layer graphenes with the layer number of N = 1-6, the hole- and electron-doped few-layer graphenes with the layer number of N =1-4 have been studied based upon the tight-binding model. It is found that in contrast with the featureless optical spectrum of the undoped monolayer graphene, the undoped AB-stacking bi-, tri-, tetra- and more-layer graphene exhibit characteristic jumps in their infrared absorption （IR） spectra, which are caused by coupling between different layers. It is also found that the clear peaks exist in the IR spectra of the hole or electron-doped hi-, tri- and tetra-layer graphenes, which are induced by the strong IR transitions between their parallel valence or conduction bands. Based upon their different IR spectra, a powerful experimental tool has been proposed to identify accurately the layer number and doping type for the few-layer graphenes.     

数学建模竞赛中大学生创新绩效影响因素的量化评估研究

学科竞赛已成为提升大学生创新绩效水平的重要途径.本文以大学生数学建模竞赛为例,量化评估影响大学生创新绩效的5个因素,通过KMO检验以及对调查结果的探索性因子与多元回归分析,得到影响大学生创新绩效评价指标的比重,其作用大小依次为:学生科研能力、师生融洽关系、团队协作情况、高校创新氛围和参与竞赛动机.根据实证分析结果可知,高校需注重培养和锻炼学生的创新思维,提升科研实践能力;增进师生在科研创新过程中的融洽关系,重视团队成员间的相互协作;营造积极向上的校园创新氛围,强化提升自我能力为主的竞赛动机;以此提升大学生参与学科竞赛的创新绩效.     

金融中的变分不等式问题

现代金融的很多决策问题在数学上可以表述成最优停时或奇异控制问题.这些问题从偏微分方程角度属于变分不等式问题,相应的自由边界对应于最优策略.本文给出金融中的一些典型的变分不等式模型、结果及尚待解决的问题.这些模型来自现代金融的3个重要研究方向:金融衍生品定价、投资组合选择及公司金融.