Observation of electron weak localization and correlation effects in disordered graphene

We have studied the electron transport properties of a disordered graphene sample, where the disorder was intentionally strengthened by Ga⁺ ion irradiation. The magneto-conductance of the sample exhibits a typical two-dimensional electron weak localization behavior, with electron-electron interaction as the dominant dephasing mechanism. The absence of electron anti-weak localization in the sample implies strong intersublattice and/or intervalley scattering caused by the disorders. The temperature and bias-voltage dependencies of conductance clearly reveal the suppression of conductance at low energies, indicating opening of a Coulomb gap due to electron-electron interaction in the disordered graphene sample. Supported by the National Natural Science Foundation of China (Grant Nos. 10774172 and 10874220), and the National Basic Research Program of China from the MOST (Grant No. 2006CB921304)     

强反射复杂表面随机缺陷检测照明系统分析

分析了采用CCD光电检测法对强反射复杂表面随机缺陷进行检测时的光学照明问题。给出了缺陷显现力的具体定义。对比了平行光和均匀散射光对消除强反射光的不同作用及对不同表面缺陷的显现力。分析了使用均匀散射光作为光源时，工件表面照度对成像质量的影响。给出了在上述条件下光照系统设计的基本原则。     

含有本征SiGe层的SiGe异质结双极晶体管集电结耗尽层宽度模型

本文分别建立了含有本征SiGe层的SiGe HBT(异质结双极晶体管)集电结耗尽层各区域的电势、电场分布模型,并在此基础上,建立了集电结耗尽层宽度和延迟时间模型,对该模型进行了模拟仿真,定量地分析了SiGe HBT物理、电学参数对集电结耗尽层宽度和延迟时间的影响,随着基区掺杂浓度和集电结反偏电压的提高,集电结耗尽层延迟时间也随之增大,而随着集电区掺杂浓度的提高和基区Ge组分增加,集电结耗尽层延迟时间随之减小. 关键词： SiGe HBT 集电结耗尽层 延迟时间     

A planar left-handed metamaterial based on electric resonators

A planar left-handed metamaterial(LHM) composed of electric resonator pairs is presented in this paper.Theoretical analysis,an equivalent circuit model and simulated results of a wedge sample show that this material exhibits a negative refraction pass-band around 9.6GHz under normal-incidence and is insensitive to a change in incidence angle.Furthermore,as the angle between the arm of the electric resonators and the strip connecting the arms increases,the frequency range of the pass-band shifts downwards.Consequently,this LHM guarantees a relatively stable torlerence of errors when it is practically fabricated.Moreover,it is a candidate for designing multi-band LHM through combining the resonator pairs with different angles.     

基于高介电常数基板和金属结构负折射材料的设计,仿真与验证

通过将单回路镜像对称开口金属环结构印制在高介电常数基板上,实现了一种金属含量比传统负折射材料更少,"双负"通带比全介质负折射材料更宽的负折射材料.分析了高介电常数基板产生负介电常数以及"双负"通带形成的机理,通过仿真实验分析了影响"双负"通带的因素.通过制作样品验证了这一机理实现"双负"的可行性,理论分析与实验结果都表明这种方法可实现较宽频段内的"双负"通带. 关键词： 负折射材料 负介电常数 负磁导率 介质谐振器原理     

γ辐照掺杂SiO2的ESR研究

分别掺有磷和硼的二氧化硅经γ辐照后产生多种顺磁性中心,ESR研究指出氧空穴O^-主要稳定在杂质离子附近.O₂^-自由基稳定在Si离子上.F心的研究认为氧缺位俘获电子存在一个动态平衡过程.     

Continuity of Effect Algebra Operations in the Interval Topology

We study the continuity of and of effect algebras in the interval topology, and present several examples of effect algebras with interesting properties.     

单长周期光栅迈克耳孙干涉仪特性研究

单长周期光栅迈克耳孙（Michelson）干涉仪是由尾纤端面蒸镀高反膜的单根长周期光纤光栅构成。入射光经长周期光栅后,部分被耦合到包层中传输。经过包层和纤芯传输的光信号经尾纤端面反射后,重新耦合回到长周期光栅中,在光栅区域形成干涉。通过理论计算分析了各种因素对其光谱响应的影响。从实验上得到了干涉光谱的谐振峰波长位移与光纤段温度变化成良好的线性关系,测得其温度系数为31．3pm／℃。表明这种结构可用于高温传感或作为波分复用滤波器。     

Reversibility window in as-quenched Ge-As-S glasses

Thermoanalytical characteristics and Raman scattering of high purity sulfur and ternary bulk glasses Ge_xAs_xS_(100−2x) for x=4-22 at. % were studied. The intermediate phase characterized by vanishing of non-reversing heat flow ΔH_nr, i.e. so-called the thermally reversing window was found between mean coordination number 〈r〉∼2.28-2.47. Separated phase of non-crystalline cycloocta-S, manifesting itself by λ-transition at ∼155 °C, was found for glasses with sulfur content higher than ∼80 at.%. Raman spectra of studied Ge-As-S glasses showed different shapes in three different areas according to three distinct phases of network glasses-floppy, intermediate, rigid.     

基于NbN，AIN技术的体声波器件研究

体声波滤波器由于其低插损、小尺寸、高带外抑制等特性，随着第三代移动通信以及蓝牙技术的发展而得到广泛研究，而MEMS技术和压电薄膜制备技术的进一步发展使高性能的体声波滤波器制作成为可能．我们以单晶MgO作为器件衬底，MgO/NbN多层结构作为AIN薄膜体声波器件的反射器，NBN／AIN／NbN三层结构为谐振器．在这样的多层结构的设计中由于各种材料之间的晶格失配小，可以获得从几十纳米到几百纳米厚度不等的单晶AIN薄膜．通过控制AIN薄膜和NbN薄膜的不同厚度，可以获得不同频段范围的谐振器．压电薄膜的质量，以及体声波在多层结构界面上的能量损耗，直接影响到谐振器电学性能．基于AIN材料的压电性能，设计了NBN／AIN／NBN三层结构的谐振器，并进行了数值模拟．