纳米锗颗粒镶嵌复合薄膜的显微结构研究

用离子束浅射技术成功地制备了Ｇｅ－ＳｉＯ２纳米颗粒镶嵌复合薄膜。采用透射电子显微镜研究了不同热处理条件下获得的薄膜样品的显微组织结构，并用Ｘ射线光电子能谱技术分析了薄膜样品的成分。研究结果表明，镶嵌纳米锗颗粒为ｆｃｃ结构、其点阵参数随着锗颗粒度的不同而有一个变化范围。     

纳米晶Ge颗粒镶嵌SiO2复合膜的多峰光致发光及其机理

用射频共溅射和热退火处理的方法制备了纳米锗颗粒镶嵌ＳｉＯ２复合薄膜，观察到了多峰的光致发光现象。发现随着激光光波长的增长，多峰发光谱的最强峰向低能方向移动，但是各子峰的位置不发生改变，而且不同样品的发光谱子峰位置非常一致，Ｘ射线光电子能谱分析显示膜中不存在纳米晶硅成分，表明多峰光致发光与镶嵌在ＳｉＯ２复合中的纳米锗颗粒有关。     

纳米晶Ge颗料镶嵌SiO_2复合膜的多峰光致发光及其机理

用射频（RF）共溅射和热退火处理的方法制备了纳米锗颗粒镶嵌SiO2复合薄膜（nc－Ge／SiO2），观察到了多峰的光致发光现象，发现随着激发光波长的增长，多峰发光谱的最强峰向低能方向移动，但是各子峰的位置不发生改变，而且不同样品的发光谱子峰位置非常一致．X射线光电子能谱（XPS）分析显示膜中不存在纳米晶硅成分，表明多峰光致发光与镶嵌在SiO2复合中的纳米锗颗粒有关。     

锗硅纳米晶材料光学性质的第一性原理研究

为了研究锗硅纳米镶嵌结构的光学性质与晶粒尺寸之间的关系,采用基于第一性原理局域密度泛函理论的平面波近似方 法对SiO2基质中的不同纳米晶粒模型进行了模拟计算,并分析了其能带结构、态密度和光学性质。结果表明,锗晶结构和硅晶结构分别 在费米能级以上3.3eV及4.3eV附近引入中间能级;微小尺寸晶粒的光吸收边随晶粒尺寸的增大先红移后蓝移。本文关于锗硅纳米晶结构 的可见光发射来自界面处缺陷的说法具有较高的可信度。镶嵌于SiO2基质中的锗纳米晶和硅纳米晶存在适用量子限制模型的最小尺寸限。 这些结论为改进材料的光学性能和深入研究纳米镶嵌材料的发光机理提供了一定的依据。     

注碳外延硅光致蓝光发射研究

N型外延硅经过碳注入、氢气氛下高温退火和电化学腐蚀后,发出峰值波长位于431nm左右的蓝色荧光。随电化学腐蚀条件的变化,蓝色荧光峰先变强后消失,并出现位于716nm处的红光峰。研究认为样品中C=O复合体杂质镶嵌在退火过程所形成的纳米硅颗粒的表面而形成的纳米硅镶嵌结构导致了蓝光发射。     

半导体锗纳米团簇和纳米层的生成与结构研究

我们在硅锗合金衬底上采用氧化等制膜方式生成零维和二维的纳米结构样品，用高精度椭偏仪(HPE)、卢瑟福背散射谱仪(RBS)和高分辨率扫描透射电子显微镜(HR-STEM)测量样品的纳米结构，并采用美国威思康新州立大学开发的Rump模拟软件对卢瑟福背散射谱(RBS)中的CHANNEL谱和RANDoM谱分别进行精细结构模拟，测量并计算出纳米氧化层与锗的纳米薄膜结构分布，并且反馈控制加工过程，优化硅锗半导体材料纳米结构样品的加工条件。我们测量出样品横断面锗纳米团簇和纳米层的PL发光谱。我们在硅锗合金的氧化层表面中首次发现纳米锗量子点组成的几个纳米厚的盖帽膜结构，我们首次提出的生成硅锗纳米结构的优化加工条件的氧化时间和氧化温度匹配公式的理论模型与实验结果拟合得很好。     

激光加工形成硅基上的氧化低维纳米结构的PL发光

用激光辐照硅样品和硅锗合金样品能够形成多种氧化低维纳米结构,可以用激光与半导体相互作用产生的等离子体波模型来解释这些结构的形成机理.其中,在单晶硅上形成的网孔壁结构有很强的706nm波长的光致发光(PL)峰,在硅锗合金上形成的多孔状结构于波长为725nm处有极强的PL峰,在硅锗合金上形成的条形片状结构分别在波长为760nm和866nm处也有较强的PL峰;这些结构表面都覆盖有氧化硅层,在硅锗合金上的氧化硅层中镶嵌有纳米锗品团簇,并用相应的模型解释了这些氧化低维纳米结构的强光致发光效应.     

激光加工形成硅基上的氧化低维纳米结构的PL发光

用激光辐照硅样品和硅锗合金样品能够形成多种氧化低维纳米结构,可以用激光与半导体相互作用产生的等离子体波模型来解释这些结构的形成机理.其中,在单晶硅上形成的网孔壁结构有很强的706nm波长的光致发光(PL)峰,在硅锗合金上形成的多孔状结构于波长为725nm处有极强的PL峰,在硅锗合金上形成的条形片状结构分别在波长为760nm和866nm处也有较强的PL峰;这些结构表面都覆盖有氧化硅层,在硅锗合金上的氧化硅层中镶嵌有纳米锗品团簇,并用相应的模型解释了这些氧化低维纳米结构的强光致发光效应.     

纳米Ge颗粒镶嵌硅基薄膜的结构与光吸收特性的研究

采用射频磁控共溅射方法制备了纳米Ge颗粒镶嵌于SiQ中的复合薄膜(Ge—SiO2)，结合样品结构对光吸收特性进行深入的研究。研究发现该类样品存在较强的光吸收，并且光吸收边随Ge颗粒尺寸变小有显著的蓝移现象。采用量子限域模型和介电限域模型分别作了相应的理论计算，结果表明两种模型的理论计算结果与实验值均有一定的偏差；在小尺寸的Ge颗粒情况下，前者与实验值有明显的差异。对此结果我们给出了相应的分析讨论。     

纳米硅镶嵌氮化硅薄膜的制备与光致发光特性

为研究氮化硅薄膜发光材料的制备工艺及其光致发光机制,实验采用射频磁控反应溅射技术与热退火处理制备了纳米硅镶嵌氮化硅薄膜材料.利用红外光谱(IR)、X射线衍射谱(XRD)、能谱(EDS)和光致发光谱(PL),对不同工艺条件下薄膜样品的成分、结构和发光特性进行研究,发现在制备的富硅氮化硅薄膜材料中形成了纳米硅颗粒,并计算出其平均尺寸.在510 nm光激发下,观察到纳米硅发光峰,对样品发光机制进行了讨论,认为其较强的发光起因于缺陷态和纳米硅发光.     

Serpentine superlattice nanowire-array lasers

We report characterization and modeling of serpentine superlattice nanowire-array lasers. These samples were grown by molecular beam epitaxy on (100) n⁺-GaAs vicinal substrates. In-plane ridge-waveguide lasers with ridge stripes either parallel or perpendicular to the nanowire arrays have been characterized at low temperatures. The measured net gain spectra at 1.4 K showed strong optical gain anisotropy such that the TM mode gain became greater than the TE mode gain when the optical cavity was placed along the nanowire direction. This provides strong evidence that the lateral quantum confinement in the serpentine superlattice is stronger than the vertical quantum confinement. Optical gain spectra in the serpentine superlattice are calculated with consideration of coupling between wires and homogeneous line broadening. A good fit to the measured polarization-dependent gain spectra is achieved when the lateral Al segregation and the homogeneous line broadening are chosen to be 8% and 7 meV, respectively. This small but finite Al segregation in the serpentine superlattice provides lateral quantum confinement for holes, which results in significant anisotropy in the relation between net gain and injection current density,     

Organic Nanoclusters on Inorganic Nanostructures for Tailoring the Emission Properties of Organic Materials

Inorganic nanostructures have been intensively studied because of their size‐dependent emission color as a result of quantum confinement effects. In contrast, no significant size dependence of the optical properties is expected for organic nanostructures owing to the weak nearest‐neighbor interactions in molecular crystals; however, the optical properties of organic materials can be significantly affected by aggregation and molecular packing, which can result in large differences between the emission spectra of solutions and thin films. Thus, the emission spectra of organic nanostructures may differ considerably from the bulk material despite the absence of quantum confinement effects. We demonstrate that 3,4,9,10‐perylenetetracarboxylicdiimide (PTCDI) nanoclusters grown on ZnO nanorods exhibit an intense blue‐white photoluminescence, different from the weak red emission of PTCDI films. Light emitting diodes consisting of ZnO nanorods and PTCDI nanoclusters also exhibited white emission.     

数字信号处理技术在新型惯导系统中应用的研究

数字信号处理是一种具有特殊结构的微处理器,可以用来快速实现各种数据信号处理算法,在新型惯导系统———光纤陀螺的应用中取得了很好的效果,使得陀螺系统质量轻,耗电少,成本低,寿命长,体积小,在军民品中都有广泛的应用前景。飞机、飞船和轮船一直都使用陀螺定位仪来导航,最新技术的定位仪是光纤陀螺,采用光纤技术的光纤陀螺很好地解决了汽车、建筑、工业机器人,天线系统和大型农场的农业机械定位问题,方便且灵敏的光纤陀螺在陀螺定位领域具有广泛的应用前景。基于萨格奈克效应（ＳａｇｎａｃＥｆｅｃｔ）的第一代干涉型光纤陀螺经过了２０年的研究历程,期间几乎所有内在与外在的噪声因素都得到了分析与消除,检测的方法也得到了很大的改进,使得光纤陀螺在军民两方面都有着重要的应用背景。     

Resonant inelastic light scattering and photoluminescence in isolated nc-Si/SiO2 quantum dots

Observation at the room temperature the spectra of the resonant inelastic light scattering by the spatially confined optical phonons as well as the excitonic luminescence caused by confinement effects in the ensemble of isolated quantum dots (QDs) nc-Si/SiO₂ is reported. It is shown that the samples investigated are high purity and high crystalline perfection quality nc-Si/SiO₂ QDs without amorphous phase α-Si and contaminants. Comparison between the experimental data obtained and phenomenological model of the strong space confinement of optical phonons revealed the need of the more accurate form of the weighted function for the confinement of optical phonons. It is shown that simultaneous detection of the inelastic light scattering by the confinement of phonons and the excitonic luminescence spectra by the confined electron-hole pairs in the nc-Si/SiO₂ QDs allows selfconsistently to determine more accurate values of the diameter of the nc-Si/SiO₂ QDs.     

Optofluidic Intracavity Spectroscopy of Canine Lymphoma and Lymphocytes

Multiple transverse mode, intracavity spectra of canine lymphoma cells in a passive Fabry-Perot cavity are distinct from single-mode spectra of normal lymphocytes. Two-dimensional effective-index modal calculations provide insight into the nuclear size versus refractive index relationship and clarify the impact of lateral optical confinement on modal shift.     

低维聚合物纳米线中的激子限域和能量传递效应研究

在共混的两种低维聚合物量子线中,采用分子自组装技术制备了嵌段低维聚合物纳米线的异质结构,通过对室温下吸收光谱、发光光谱和激发光谱的研究,证实了在这种嵌段低维聚合物纳米线的异质结构中存在很强的激子限域效应以及链内和链间的能量传递效应。     

成像光谱仪“混光”特性分析

成像光谱仪是新型多光谱遥感器，它具有获得地面的更丰富光谱信息的特点。无论采用滤光片分光还是色散元件分光，都不同程度地存在光空间的混杂。文中分析成像光谱仪“混光”特性，提出保障系统光谱特征和空间特性的判据。     

Structural,Optical, and Electrical Properties of Cobalt-Doped CdS Quantum Dots

In the present work, a systematic study has been carried out to understand the influence of cobalt (Co) doping on various properties of CdS nanoparticles. CdS and Co-doped CdS quantum dots have been prepared at room temperature using a chemical precipitation method without using catalysts, capping agents, or surfactants. X-ray diffraction reveals that both undoped and Co-doped CdS nanoparticles exhibit hexagonal structure without any impurity phase, and the lattice constants of CdS nanoparticles are observed to decrease slightly with increasing cobalt concentration. High-resolution transmission electron microscopy (HRTEM) shows that the particle size of CdS and 5.02% Co-doped CdS nanoparticles is in the range of 2 nm to 4 nm. The Raman spectra of Co-doped CdS nanoparticles exhibit a red-shift compared with that of bulk CdS, which may be attributed to optical phonon confinement. The optical absorption spectra of Co-doped CdS nanoparticles also exhibit a red-shift with respect to that of CdS nanoparticles. The electrical conductivity of CdS and Co-doped CdS nanoparticles is found to increase with increasing temperature and cobalt concentration.     

High-coupling-efficient 1.3-μm laser diodes with goodtemperature characteristics

We have proposed uniformly beam-expanded structures based on the advanced concept for realizing high coupling efficiency and good temperature characteristics. Beam expansion (optical confinement reduction) by narrowing the core layer width as well as a carrier confinement are strongly enhanced by adopting a larger bandgap InGaAsP for MQW barriers and separate confinement heterostructure layers. These laser diodes (LD's) were fabricated by the conventional buried heterostructure laser process, which is very important in reducing the cost. Our results have proven the effectiveness of our proposition. The LD's with high coupling efficiency (-3.2 dB) and good temperature characteristics have been achieved even using the simple approach of reducing optical confinement. The threshold currents at 25 and 85°C are 9.3 and 39.4 mA, respectively. The slope efficiency at 25°C is 0.39 W/A and still high (0.26 W/A) even at 85°C     

Photoelastic channel optical waveguides in epitaxial GaAs layers

Photoelastic channel optical waveguides have been fabricated in GaAs epitaxial layers. These waveguides exhibit strong lateral confinement in a single region of their cross-section. They compare favourably with previously demonstrated integrated optical waveguide structures.