拉曼光谱和红外光谱分析沉积气压对微晶硅薄膜微结构的影响

采用射频等离子体增强化学气相沉积法(RF-PECVD),在玻璃和硅衬底上以230—310Pa之间的沉积气压生长微晶硅(μc-Si:H)薄膜。利用拉曼光谱和红外光谱分析样品的微结构。结果发现样品的微结构强烈依赖于沉积气压,并且存在着最佳沉积气压250Pa,在此条件下的微晶硅薄膜晶化率为60.6%,氢含量为最小值9.1%。     

Formation of Iron Silicides Under Graphene Grown on the Silicon Carbide Surface

Physics of the Solid State - The formation of iron silicide thin films under graphene grown on the silicon carbide surface is investigated. The thin films are synthesized by consecutive...     

Microdisperse Iron Silicide Structures Produced by Implantation of Iron Ions in Silicon

Iron implanted and subsequently annealed n-type Si(111) was studied by conversion electron Mössbauer spectroscopy for phase analysis and Auger electron spectroscopy for sputter depth profiling and element mapping. During implantation (200 keV, 3 × 10¹⁷ cm^?2, 350°C) a mixture of β- and α-FeSi₂ is firmed and after the subsequent annealing (900°C for 18 h and 1150°C for 1 h) a complete transition to the β- and the α-phase can be detected. The as-implanted profile has Gaussian shape and is broadening during annealing at 900°C to a plateau-like profile and shows only a slight broadening and depth depending fluctuations of the iron concentration after the 1150°C annealing. With scanning Auger electron spectroscopy the lateral iron and silicon distribution were investigated and show for the sample annealed at 900°C large separated β-FeSi₂ precipitates which grow due to the process of Ostwald ripening. At 1150°C additionally coalescence of the precipitates occur and a wide extended penetration α-FeSi₂ network structure is formed.     

High Pressure Study of HfNi Crystallographic and Electronic Structure

The crystallographic structure and electronic properties of HfNi were studied as a function of pressure by combining X-ray diffraction results with the full potential linearized augmented plane wave (LAPW) calculations. No phase transition was observed up to a pressure of 35.3 GPa, with a total volume contraction of V/V ₀ = 0.85, a bulk modulus value of B ₀ = 52 ± 3 GPa and B ₀ ^′ = 1.29 ± 0.26. The calculated linear increase in the V _zz value as a function of the pressure induced volume reduction at the hafnium site was attributed mainly to the p–p contribution, while in the nickel site, a non negligible d–d contribution to V _zz is also observed, and attributed to the high 3d-partial DOS near the nickel nucleus. Based on the total electronic DOS at E _Fermi calculated for 0 K (N(E ⁰ _Fermi)), a value of 6.85 and 5.03 (mJ/mol/k²) was calculated for the band contribution (γ _band) to the electronic specific heat coefficient (γ) at a pressure of 0 and 35.3 GPa, respectively.     

原子发射光谱法测定镁砂中的硅和铁

镁砂是生产烧结焊剂的重要原料。本文采用原子发射光谱分析法，通过加入合金的缓冲剂，并选择合理的内标，成功地对镁砂中的硅和铁进行了测定。     

电感耦合等离子体-原子发射光谱法测定铁精矿粉中的氧化硅

通过系统考察铁精矿粉的分解方法以及熔剂的配比实验,确定铁精矿粉分解完全的实验方法,并进行了光谱干扰、放置时间、基体效应、精密度、准确度和对照等实验.与分光光度法和重量法相比此方法准确、快速.试样熔融方法与铁矿石的国家标准分析方法相比更适合于铁精矿粉的分析.测定范围在0.20％-10.00％之间.     

金刚石线锯切割多晶硅片的气相刻蚀制绒研究

采用气相刻蚀制绒法研究金刚石线锯切割多晶硅片制绒.加热体积比1∶3、总体积400 mL的HF-HNO3酸混合溶液到90℃,使酸混合溶液受热产生气相,利用气相对金刚石线锯切割多晶硅片表面进行制绒.结果表明,制绒15 min之后,硅片表面的切割纹被完全去除;小腐蚀坑密布硅片表面,尺寸小于1μm,而传统湿法酸制绒所形成的腐蚀坑尺寸大于10μm.气相刻蚀后的金刚石线锯切割多晶硅片表面的微观粗糙度比传统酸混液制绒后的金刚石线锯切割多晶硅片表面的微观粗糙度高3倍多.气相制绒效果明显,并仅有12.11％的低反射率.     

基于激光诱导击穿光谱技术检测分析原铝中硅、铁元素含量

利用自行搭建的LIBS装置对原铝中硅铁含量进行了分析测试，测试前对原铝试样进行了微观形貌分析，研究发现原铝中硅元素除有个别区域聚团现象外，其分布相对较为均匀；铁元素多以团状汇聚形态出现，且无明显的分布规律。实验分别考察了激光脉冲能量对激光诱导原铝等离子体光谱的影响，发现随着激光脉冲能量的增大，硅、铁元素信噪比先增加后减小，硅、铁谱线信噪比最大值均出现在160 mJ处，实验选取的激光脉冲能量为160 mJ。在上述较为合理的实验条件下，以内标法为基础，分别采用两种标样（纯铝标样与自选标样）建立了定标模型；结果表明：相比于纯铝标准试样，采用自选试样建立的定标模型不够理想，且数据的离散程度较大，铁元素直线拟合优度仅为0.921 3，相对标准偏差也较大。采用纯铝标样时，在试样不旋转的情况下，硅、铁元素定标曲线拟合优度分别为0.961 1与0.974 1，相对标准偏差分别为8.85%与9.43%，且误差棒显示误差随定标试样的硅、铁含量升高而增大。当试样台保持转速50 r·min-1条件下进行实验，发现硅、铁元素定标曲线的拟合优度分别为0.978 5与0.988，相对标准偏差分别为3.78%与3.4%，相比于试样平台固定情况下的定标结果，拟合优度明显改善，相对标准偏差也有所降低，定标模型明显优于自选试样建立的模型。使用两种定标模型对25个测试样进行了分析测试，比较了两种测试结果的相对误差，纯铝定标试样由于含量梯度较大，跨度较宽，采用该标样建立的定标模型对低铁原铝试样测试适应性相对较差，而自选试样建立的定标模型虽然不够理想，但针对低铁原铝试样的测试适应性相对较好。对激光诱导原铝产生的等离子体进行了诊断，通过镁元素几条离子谱线的玻耳兹曼图，计算出了等离子体温度约为9 163.63 K，利用镁元素一条谱线的Stark展宽估算出等离子体电子密度为1.69×1017 cm-3，验证了激光诱导原铝等离子体处于局部热力学平衡状态的假设是成立的。     

火焰原子吸收光谱法测定工业硅中钙和铁

本文介绍了火焰原子吸收光谱法测定工业硅中钙和铁，研究了样品制备方法及其共存元素的干扰情况，在选择好的实验条件下，检出限分别为钙０．００５％，铁０．００３％。相对标准偏差小于１０％，本法准确度及精密度均达到满意结果，方法简便、快速。     

Structural Anisotropy of Amorphous Silicon Films Modified by Femtosecond Laser Pulses

It is demonstrated that the surface-relief orientation in the form of one-dimensional gratings with a period of 1.20 ± 0.02 μm formed under processing of hydrogenated-silicon films by femtosecond laser pulses (1.25 μm) with an energy density of 0.15 J/cm² is determined by the direction of the polarization vector of the radiation and total laser exposure. Based on the results of the analysis of Raman spectra, the presence of a nanocrystalline phase of silicon with a volume fraction between 15 and 67% (depending on processing conditions) is detected. The observed processes of micro- and nanostructuring are caused by excitation of the surface plasmon–polaritons and nanocrystallization in the near-surface region in the field of high-power femtosecond laser pulses, respectively. In addition, formation of polymorph modifications of silicon Si-III and Si-XII under femtosecond laser processing with a number of pulses exceeding 500 is discovered. Anisotropy of the Raman signal for the above polymorph modifications is revealed.     

X-Ray Diagnostics of Microstructure Defects of Silicon Crystals Irradiated by Hydrogen Ions

Technical Physics - Features of formation and transformation of radiation defects in near-surface layers of silicon plates that are implanted with hydrogen ions are studied. Using the method of...     

一种轴向核苷修饰硅酞菁的合成与光动力抗癌活性

合成了一种轴向核苷修饰硅酞菁,即二[5′-(2′,3′-O-异丙基)-5-甲基胞苷氧基] 硅酞菁,并通过1H NMR和HR-MS等手段进行了表征。该化合物在N,N-二甲基甲酰胺和含1% Cremophor EL水溶液中以单体形式存在,Q带最大吸收波长分别位于676和679 nm,荧光发射峰分别位于685和689 nm。离体光动力抗癌活性表明,该化合物具有显著的光动力抗癌活性,对人肝癌细胞HepG2的半致死浓度(IC₅₀)低至7.8×10-8mol·L-1。荧光共聚焦显微镜研究显示,SiPcG可定位于细胞线粒体中。研究表明,SiPcG是一种有发展潜力的新型抗癌光敏剂。     

导数分光光度法同时测定金属硅中铁和铝的研究

本文研究了用一阶导数分光光度法同时测定金属硅中铁和铝的方法，在ＰＨ＝６．７醋酸铵缓冲溶液中，乳化剂ＯＰ存在下，Ｆｅ＾３＋、Ａｌ＾３＋与铬天青Ｓ形成的配合物－阶导数光谱分别在６３４．６、６０８．８ｎｍ处有等吸收点，利用两波长处的一阶导数光谱值可同时测定混合体系中Ａｌ＾３＋、Ｆｅ＾３＋含量，二者互不干扰，Ｆｅ＾３＋、Ａｌ＾３＋含量分别在０－２０μｇ／２５ｍＬ、０－１０μｇ／２５ｍＬ范围内与一阶导数光谱     

用发射光谱法连续摄谱检测铸铁中的硅、锰、镁

采用高压火花光源，一次预烧，连续摄谱的发射光谱法定量分析铸铁中硅，锰、镁三元素，加快了分析速度，可测定质量百分数为1.50%-3.50%的硅、0.40%-1.10%的锰，0.010%-0.090%的镁，其相对标准偏差分别为硅1.9%，锰3.0%，镁10.4%。     

红外光谱法研究射频功率对微晶硅薄膜微结构的影响

采用射频等离子体增强化学气相沉积(RF-PECVD)技术,在硅衬底上以不同的射频功率生长微晶硅(μc-Si:H)薄膜,利用傅里叶变换红外透射光谱技术对薄膜进行测试.通过对红外透射光谱的高斯拟合分析,结果表明薄膜中的氢含量和硅氢键合模式跟射频功率密切相关;当射频率从30W增加到110W时,薄膜中的氢含量先减少后慢慢增加,而结构因子逐渐增加后再减小,并且硅氢键合模式由以SiH为主转变为以SiH2为主.并讨论了这些参量随射频功率变化的机理.     

Overview of Microstructure and Microtexture Development in Grain-oriented Silicon Steel

This paper outlines the development of the microstructure and microtexture of grain-oriented silicon steel during the industrial production process. In particular the evolution of the Goss orientation was studied in industrial material as well as in single crystal experiments.     

Preparation of Photoluminescent Porous Silicon Nanoparticles by High‐Pressure Microfluidization

The use of high‐shear microfluidization as a rapid, reproducible, and high‐yield method to prepare nanoparticles of porous silicon (pSi) with a narrow size distribution is described. Porous films prepared by electrochemical etch of a single‐crystal silicon wafer are removed from the substrate, fragmented, dispersed in an aqueous solution, and then processed with a microfluidizer, which generates high yields (57%) of pSi nanoparticles of narrow size distribution (PDI = 0.263) without a filtration step. Preparation of pSi nanoparticles via microfluidization improves yields (by 2.4‐fold) and particle size uniformity (by 1.8‐fold), and it lowers the total processing time (by 36‐fold) over standard ultrasonication or ball milling methods. The average diameter of the nanoparticles can be adjusted over the range 150–350 nm by appropriate adjustment of processing steps. If the fluid carrier in the microfluidizer contains an oxidant for Si, the resulting pSi particles are prepared with a core–shell structure, in which an elemental Si core is encased in a silicon oxide shell. When an aqueous sodium tetraborate processing solution is used, microfluidization generates photoluminescent core–shell pSi particles with a quantum yield of 19% in a single step in less than 20 min.     

Microstructure and Corrosion Performance of Carbonitriding Layers on Cast Iron by Plasma Electrolytic Carbonitriding

The surface carbonitriding of cast iron is investigated in an aqueous solution of acetamide and glycerin. Microstructure, chemical and phase composition and corrosion performance of the carbonitriding layers are investigated by scanning electron microscopy, energy dispersive spectroscopy and x-ray diffraction, as well as potentiodynamic polarization testing. X-ray diffraction results show that the carbonitriding coatings are composed of martensite, anstenite（γ-Fe）, Fe2C, Fe3C, Fe5 C2, FeN and ε-Fe2-3N. After the plasma electrolytic carbonitriding treatment the corrosion resistance of cast iron is clearly improved compared to the substrate, and the coatings produced at 350 V for 30s give the best corrosion resistance.