ZnO/Si纳米孔柱阵列的真空蒸镀及其光致发光特性

以硅纳米孔柱阵列(Si-NPA)为衬底,通过采用真空蒸镀技术沉积金属锌,再在纯氧气氛中进行氧化退火的方法,制备出具有阵列特征的ZnO/Si-NPA异质结构材料.研究发现,ZnO/Si-NPA的表面形貌、结构和光致发光特性强烈依赖于氧化退火温度.当氧化退火温度低于400 ℃时,样品的发光主要来自于Si-NPA衬底;当氧化退火温度高于700 ℃时,样品的发光主要来自于ZnO薄膜;经过600 ℃氧化退火的样品则同时包含有来自于Si-NPA和ZnO薄膜的发光.上述结果表明,通过控制ZnO/Si-NPA制备过程中的氧化退火温度,可以在一定程度上实现对其光致发光谱的有效调控.这对未来制备具有特定功能的半导体光电器件具有重要的实际意义.     

Multipeak-structured photoluminescence mechanisms of as-prepared and oxidized Si nanoporous pillar arrays

Silicon dominates the electronic industry, but its poor optical properties mean that it is not preferred for photonic applications. Visible photoluminescence (PL) was observed from porous Si at room temperature in 1990, but the origin of these light emissions is still not fully understood. This paper reports that an Si nanocrystal, silicon nanoporous pillar array (Si-NPA) with strong visible PL has been prepared on a Si wafer substrate by the hydrothermal etching method. After annealing in O₂ atmosphere, the hydride coverage of the Si pillar internal surface is replaced by an oxide layer, which comprises of a great quantity of Si nanocrystal (nc-Si) particles and each of them are encapsulated by an Si oxide layer. Meanwhile a transition from efficient triple-peak PL bands from blue to red before annealing to strong double-peak blue PL bands after annealing is observed. Comparison of the structural, absorption and luminescence characteristics of the as-prepared and oxidized samples provides evidence for two competitive transition processes, the band-to-band recombination of the quantum confinement effect of nc-Si and the radiative recombination of excitons from the luminescent centres located at the surface of nc-Si units or in the Si oxide layers that cover the nc-Si units because of the different oxidation degrees. The sizes of nc-Si and the quality of the Si oxide surface are two major factors affecting two competitive processes. The smaller the size of nc-Si is and the stronger the oxidation degree of Si oxide layer is, the more beneficial for the luminescent centre recombination process to surpass the quantum confinement process is. The clarification on the origin of the photons may be important for the Si nanoporous pillar array to control both the PL band positions and the relative intensities according to future device requirements and further fabrication of optoelectronic nanodevices.     

氧化锌/硅纳米孔柱阵列的结构和光致发光特性研究

以硅纳米孔柱阵列(Si-NPA)为衬底、用化学气相沉积法制备了具有规则阵列结构特征的ZnO/Si-NPA纳米复合体系，并对其结构和光致发光性质进行了表征. 实验结果显示，组成ZnO/Si-NPA表面阵列的每个柱子均呈现层壳结构. 不同于衬底Si-NPA的红光和蓝光发射，ZnO/Si-NPA在紫外光区和蓝绿光区呈现出两个强的宽发光峰. 分析表明，紫外光发射应归因于ZnO晶体的带边激子跃迁；而蓝绿光发射则来自于ZnO晶体本征缺陷所形成的两类深能级复合中心上载流子的辐射跃迁.     

硅纳米孔柱阵列的结构和光学特性研究

采用水热腐蚀技术在单晶硅衬底上制备出一种新的硅微米／纳米结构复合体系——硅纳米孔柱阵列(Si-NPA)，并对其表面形貌、结构及光学特性进行研究.Si-NPA的结构复合性体现为 在微米和纳米两个尺度上形成了三个分明的结构层次，即微米尺度的硅柱阵列结构、硅柱上 的纳米多孔结构以及组成孔壁的硅纳米晶粒.积分光反射谱和荧光光谱测试表明，Si-NPA具 有良好的光吸收和光致发光特性.依据Si－NPA积分反射谱的实验数据，采用Kramers-Kronig 变换关系计算得到了Si-NPA的复折射率和复介电函数、吸收系数等光学常数，并由此讨论了 Si-NPA相对于单晶硅的光学特性发生显著变化的原因.最后，通过分析Si-NPA的光吸收系数 与入射光子能量之间的关系，揭示出Si-NPA具有直接带隙半导体的电子结构特征，而且理论 计算得到的Si-NPA的带隙能与其光致发光谱的峰位能很好符合. 关键词： 硅纳米孔柱阵列 光学特性 电子结构 水热腐蚀     

OEM代工模式和原厂制造孰优孰劣

＂原厂制造与OEM代工孰优孰劣,是仁者见仁、智者见智的话题。＂目前,活跃在中国笔记本电脑市场的品牌厂商可以分为两大阵容：一大阵营是三星和富士通等坚持原厂生产的厂商;而另一阵营是联想、戴尔、惠普等以OEM代工为主的厂商。一直以来,原厂制造与OEM代工孰优孰劣,在业内是一个仁者见仁、智者见智的话题。     

基于双稳态势能调节的仿生纤毛流速传感器

针对流速传感器的高分辨率需求,提出了一种基于双稳态势能调节的仿生纤毛流速传感器。该传感器由纤毛、电极层、上部结构层、中间连接层和下部支撑层等多层结构构成,其中上部结构层一方面采用不对称梳齿结构实现差分电容检测,另一方面布置周期性调制梳齿实现系统势能函数呈现双稳态。通过流体-固体力学-静电多物理场耦合分析,得到电容随流速的变化关系,分辨率优于0.001m/s,另外通过调制梳齿的静电场分析,绘制出系统势能函数曲线。最后,基于MEMS加工技术,通过设计合理的工艺流程制备出了该传感器。     

基于STM32和ZigBee的微电容在线检测系统

为了构建电容式无线微传感器网络,设计了基于STM32单片机和ZigBee的微电容在线检测系统。该系统由上位机 和下位机组成,使用TI公司的CC2530 ZigBee模块进行无线通信,下位机采用STM32F103单片机控制AD7746采集电容数据,通过ZigBee路由器节点无线发送,上位机使用ZigBee协调器节点无线接收数据,并且基于Visual Studio 2015开发了上位机软件对数据进行实时显示。结果表明:该系统可以准确地测量电容信号,具备低功耗,组网方便,传输稳定可靠等特点,具有较好的应用前景。     

Quantitative and sensitive detection of prohibited fish drugs by surface-enhanced Raman scattering

Rapid and simple detections of two kinds of prohibited fish drugs, crystal violet(CV) and malachite green(MG),were accomplished by surface-enhanced Raman scattering(SERS). Based on the optimized Au/cicada wing, the detectable concentration of CV/MG can reach 10~(-7) M, and the linear logarithmic quantitative relationship curves between log I and log C allows for the determination of the unknown concentration of CV/MG solution. The detection of these two analytes in real environment was also achieved, demonstrating the application potential of SERS in the fast screening of the prohibited fish drugs, which is of great benefit for food safety and environmental monitoring.     

Preparation, structural and electrical properties of zinc oxide grown on silicon nanoporous pillar array

Polycrystalline thick film of zinc oxide (ZnO) is grown on a unique silicon substrate with a hierarchical structure, silicon nanoporous pillar array (Si-NPA), by using a vapour phase transport method. It is found that as-grown ZnO film is composed of closely packed ZnO crystallites with an average size of $\sim$10\,\mu$m. The film resistivity of ZnO/Si-NPA is measured to be $\sim$8.9\Omega\cdot$\,cm by the standard four probe method. The lengthwise $I$-$V$ curve of ZnO/Si-NPA heterostructure is measured. Theoretical analysis shows that the carrier transport across ZnO/Si-NPA heterojunction is dominated by two mechanisms, i.e. a thermionic process at high voltages and a quantum tunnelling process at low voltages.     

PC产业将向巨头化趋势发展

从世界上第一台PC诞生以来，时光已掠过30年。30年的发展历程，PC产业已以迅猛的速度造就了IT行业和人们生活繁盛期的同时，也造就了千百万的发烧友和爱好者，让中国PC产业发生了质的蜕变。