LPCVD氮化硅薄膜的室温可见光发射

在4.66eV的激光激发下,在室温下LPCVD氮化硅薄膜可发射高强度可见光,其峰位位置分别为2.97,2.77,2.55,2.32,2.10和1.90eV的6个PL峰,建立了可见光发射的能隙态模型,讨论了发光机制     

The band gap of 1D viscoelastic phononic crystal

The band gap of one dimensional (1D) phononic crystal with viscoelastic host material is studied in this paper. The standard solid model is used to simulate the viscoelastic behavior of the host material and the fillers embedded in the host material are still assumed elastic material. The band gap problem in 1D phononic crystal leads to an eigenvalue problem by using the plane wave expansion method and the Bloch–Floquet wave theory in a periodic structure. An iterative algorithm is designed to obtain the band gap structure due to the dependence of elastic constants on frequency for the viscoelastic host material. A numerical example is given for steel/epoxy phononic crystal. The band gap of 1D phononic crystal is evaluated for different viscoelastic constants, namely, relaxation time, initial and final state elastic modulus. It is found that the viscoelastic constants of host material affect not only the location but also the width of band gaps.     

Preparation of wide gap Cu(In,Ga)S2 films on ZnO coated substrates

We have prepared Cu(In,Ga)S₂ films at growth temperatures from 300 °C to 580 °C with a homogeneous gallium depth distribution (estimated band gap 1.67 eV) onto soda lime glass (SLG) substrates with one of three different kinds of back contact: Mo(1000 nm), ZnO(500 nm), and Mo(30 nm)/ZnO(500 nm), respectively. We have also investigated the depth profiles of Zn and Na (diffused from SLG) in Cu(In,Ga)S₂ films by secondary ion mass spectroscopy (SIMS). The efficiency of solar cells on Mo increases with increasing growth temperature. It is higher on Mo/ZnO than on ZnO, and increases from 350 °C to 450 °C, then decreases above 450 °C. It was observed by SIMS that the amount of Zn in Cu(In,Ga)S₂ on Mo/ZnO is lower than it is on ZnO up to 450 °C, and a large amount of Zn diffuses into absorbers over 450 °C, which contributes to decreasing efficiency. The amount of Na in the back contact increases with growth temperature. The depth distribution of Na in Cu(In,Ga)S₂ films on Mo is almost constant in the order of 10¹⁷-10¹⁸ cm^− 3, on ZnO and Mo/ZnO the Na concentration increases towards the surface and is in the range of 10¹⁵-10¹⁷ cm^− 3.     

二维复合三角格子光子晶体FDTD带隙结构分析

设计一种二维复合三角晶格结构光子晶体,采用时域有限差分法数值计算了这种光子晶体的带隙结构。计算结果表明,介质圆柱在空气中按复合三角形排列存在E偏振和M偏振模完全重叠的光子带隙区,即具有绝对光子带隙。绝对光子带隙的宽度与介质柱的介电常数有关,介电常数差越显著越有     

铝合金焊接图像焊缝位置和间隙提取

基于自行设计的CCD被动视觉传感系统,在仅依靠电弧光照明的情况下,实现了钨极氩弧焊过程中实时提取清晰的熔池正前方图像.通过分析退化恢复、平滑后的图像间隙处灰度值特点,采取了特定区域自动域值分割、空穴检出法统计各8-连通域面积、基于8-领域面积阈值去噪、面积统计转换等步骤可以求得间隙值,进一步进行间隙细化,最后采用Hough小变换对细化后的间隙点进行拟合,检测出焊缝位置.     

强化金属材料强化系数对矫直机辊缝设定的影响分析

介绍了金属带材弹塑性变形弯曲基本理论和概念,建立了过拉伸因子OS(Overstrech fac-tor)与塑区比P(rate of plastification)之间的对应关系,指出金属带材在反复弯曲过程中,变形程度最大处OS取值为7比较合理,此时金属带材变形塑区比为85%。对强化金属材料强化系数对矫直机辊缝设定的影响进行了模拟计算和分析,结果表明:要想达到相同的塑区比,强化系数越大,所需的压下量就越大;但当强化系数小于0.01时,与理想金属材料相比,增大的压下量微乎其微,可按理想金属材料近似处理,根据某精整分厂现有产品大纲,带钢的强化系数一般不超过0.01,因此在辊缝预设定模型中,为了简化计算,均按理想金属材料处理,对带钢矫直效果无明显影响。     

管端钢骨架大间隙径向外抱式强制密封

介绍了国内外钢管水压试验机管端常用的小间隙径向密封和端面密封的结构及工作原理,详细阐述了钢骨架大间隙径向外抱式强制密封结构、性能、工作原理及其与常规密封的比较。实际生产应用表明,钢骨架大间隙径向外抱式强制密封装置引管方便,胶圈使用寿命长,可大大提高生产效率。     

氮化铜薄膜的研究

氮化铜(Cu_3N)薄膜是一种新型的电、光学材料,它具有典型的反三氧化铼结构,由于Cu原子没有很好地占据(111)晶格面的紧密位置.在薄膜中掺杂之后,薄膜的电、光学性质会发生显著变化.Cu_3N在较低温度下会分解为Cu和N_2.介绍了Cu_3N的制备方法,总结了该膜制备方法和工艺参数对薄膜结构的影响,分析了在不同N_2分压下薄膜由(111)晶面转向(100)晶面择优生长和薄膜定向生长的原因,讨论了薄膜的电学、光学、热学等物理性质及其在相关方面的应用,并对该膜的物理性质与结构之间的关系作了简要分析.     

Complex susceptibility analysis of magneto-fluids: Optical band gap and surface studies on the nanomagnetite-based particles

An aqueous stable magnetic fluid containing Fe₃O₄ nano-particles with a mean diameter of 4–7 nm, which is in the range of super-paramagnetism, is prepared. The particles are synthesized via co-precipitation method from ferrous and ferric solutions. X-ray diffraction, transmission electron microscopy, transformer method are used to study the physical properties of the magnetic fluids and powders. A method is given to analyze and resolve the real and imaginary parts of the measured complex susceptibility of magnetic fluids. The band gap parameters of the magneto-nanopowders such as the direct-, indirect-band gap energies, Fermi energy and Urbach energy are determined. A comparative study between the different techniques used to calculate the powder particle size is presented. Adsorption of nitrogen gas is used to identify and determine the particles mean diameter and to study their microstructure, the magnetic properties and surface porosity. The study showed that the total pore system of the magnetic nano-powders consists mainly of mesopores.     

Superfluid Density and Angular Dependence of the Energy Gap in Optimally Doped (BiPb)2(SrLa)2CuO6+δ

We present a muon-spin rotation study of the optimally doped cuprate superconductor (BiPb)₂(SrLa)₂ CuO_6+δ . The measured magnetic field dependence of the in-plane magnetic penetration λ _ab suggests superconductivity with a dominant d-wave order parameter. The comparison of the temperature dependence of λ _ab with calculations, assuming the angular gap symmetry as obtained from photoemission measurements, is consistent with a partial suppression of the quasi-particle weight towards the anti-nodal region of the Fermi surface. This suggests that the superconducting and the pseudogap state are dominated by different parts of the Fermi surface.