In Situ FT-IR Study of an Electron-Beam Induced Reaction of C60 Film

Abstract

The structural modification induced by electron-beam (EB) in a C₆₀ film and its kinetics have been studied using in situ high-resolution FT-IR spectroscopy. Similar to studies on photoirradiated K_xC₆₀ fim, was found that a coalescence reaction between adjacent C₆₀ molecules takes place. In order to investigate the interaction between an incident electron and Cgg molecules, the time-dependence of the amounts of C₆₀ on the EB irradiation was examined. It was found that the reaction rate exhibits a linear dependence on the reactant concentration and nonlinear dependence on the incident current.     

Electron Beam Induced Changes of the Real Structure of Semiconductors

The formation of irradiation defects produced in a high voltage electron microscope (HVEM) has been studied in Ge and other semiconductor crystals in dependence on various thermal treatments and on covering of the specimen surface. It has been concluded that the defect formation depends — besides general features known for pure metals — also on the state of electrically neutral impurities. Besides, various interactions between dislocations and irradiation defects were observed.     

稀磁Zn1-xNixO纳米棒的水热法制备与磁性能研究

采用水热法成功制备了不同浓度的Zn1-xNixO(x =0,0.01,0.05,0.10,0.20)稀磁半导体材料,并利用X射线衍射(XRD)、透射电子显微镜(TEM)、选区电子衍射(SAED)、X射线能量色散分析(XEDS)、拉曼(Raman)光谱和振动样品磁强计(VSM)对其晶体结构、形貌、组成元素和磁学性能等进行表征,实验结果表明,本方法所制备的不同掺杂浓度的Zn1-xNixO稀磁半导体样品具有结晶良好的纤锌矿结构,没有杂峰出现,样品中的Ni2+全部进入ZnO晶格中替代了部分Zn2+的格点位置,生成单一相的Zn1-xNixO,样品形貌都为纳米棒状结构,分散性良好.Zn1-xNixO样品在室温条件下存在明显的铁磁性,饱和磁化强度都随着Ni2+掺杂量的增加而呈现出先增加后减小的趋势,同时样品的单个镍原子的磁矩是逐渐下降的.     

含铅GaSb基半导体的热电输运特性

GaSb是Ⅲ-Ⅴ族系列直接带隙半导体材料,其内部的缺陷性质对调控材料的热电性能具有重要作用.研究发现,在GaSb中掺杂Pb后材料内部产生了大量的反结构受主缺陷Pbsb-及施主缺陷PbCa+,但本征缺陷VGa3-和SbGa2+浓度减少.这些缺陷浓度的变化直接调控了材料的热电输运性能.例如,掺杂0.25; Pb后,室温载流子浓度由未掺杂时的～5.04 ×1023m-3突增到9.50×1025 m-3;在867 K时,电导率由0.56×104 Ω-1·m-1增加到4.82×104 Ω-1·m-1;晶格热导率由4.63 W· K-1·m-1下降到3.41 W· K-1·m-1.最大热电优值(ZT)为0.21,约是未掺杂GaSb最大ZT值的10倍.     

Thermal Expansion Coefficient of Binary Semiconductors

The linear thermal expansion coefficient of tetrahedrally coordinated A^IIB^VIand A^IIIB^Vsemiconductors has been calculated using plasmon energy data. A simple relation between the bond length and plasm on energy has been derived. The calculated values of thermal expansion coefficient and bond length have been compared with the experimental values and the values reported by differentworkers. An excellent experiment has been obtained between them.     

Structure and Properties of Nanostructured SZO Films Obtained by Electron-Beam Evaporation

Crystallography Reports - The composition, structure and properties, as well as the current–voltage characteristics (CVCs) of nanostructured SZO films were studied. These films were...     

Study of the Processes Induced by Femtosecond Laser Radiation in Thin Films and Molecular-Cluster Beams Using Ultrafast Electron Diffraction

Crystallography Reports - The coherent lattice dynamics in thin crystalline Sb and Bi films has been investigated using ultrafast electron diffraction. The samples were exposed to Ti:sapphire...     

废旧碱性电池共沉淀法制备锰锌铁氧体的研究

以硫酸溶解废旧碱性锌锰电池所得溶液为原料,用NH4HCO3与NH3·H2O组成沉淀剂,采用并加共沉淀法制备出锰锌铁氧体.借助于原子吸收分光光度计对沉淀条件进行优化;借助于XRD、IR等手段对产物组成晶型进行检测;借助于SEM及TEM等手段对产物形貌进行表征;借助于振动样品磁强计对产物磁性能进行检测,并对产物组成进行优化.结果表明:共沉淀的适宜条件为T=50～55℃、pH=6.5～7.5;煅烧温度为1130～1160℃、煅烧时间为2h;产物最佳组成为Mn0.6Zn0.4Fe2O4;其形状近似为球形、具有粒径小、分散均匀、磁性能优良等特点.     

光纤微透镜侧面镀膜方法和应用的研究

研究了采用光纤微透镜作为半导体激光器光斑快轴压缩透镜的方法.通过在光纤的两个对称侧弧面镀制增透膜,减少了光纤微透镜对光的反射,其反射率由原来的4;降低到0.3;以下,有效的避免了形成激光器的腔外腔,进而消除了因半导体激光器快轴压缩造成波长谱线侧峰的形成.研究结果表明,在光纤透镜的部分弧面镀膜是可行的,弧面镀膜部分可以减少对半导体激光器发光的反射,达到增透的目的,非常有利用于半导体激光器的输出光斑整形.     

二次退火制备Ⅲ-Ⅴ族半导体量子点

利用离子注入法在一块Si(001)衬底上注入了In+和As+,注入能量分别为210keV,150keV,注入剂量6.2×1016cm-2,8.6×1016cm-2,另一块Si(001)衬底上注入Ga+和Sb+,注入能量分别为140keV,220keV,注入剂量分别为8.2×1016cm-2,6.2×1016cm-2,然后对样品分别经过一次退火和二次退火处理制备出了Si基量子点材料。用透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)观察了退火后量子点截面像,用PL探测量子点的光致发光谱,发现经二次退火生长的量子点微晶格结构和Si衬底损伤的修复均明显优于一次退火。     

基于碳化硅衬底的宽禁带半导体外延

宽禁带半导体具备禁带宽度大、电子饱和飘移速度高、击穿场强大等优势,是制备高功率密度、高频率、低损耗电子器件的理想材料。碳化硅(SiC)材料具有热导率高、化学稳定性好、耐高温等优点,在SiC衬底上外延宽禁带半导体材料,对充分发挥宽禁带半导体材料的优势,并提升宽禁带半导体电子器件的性能具有重要意义。得益于SiC衬底质量持续提升及成本不断降低,基于SiC衬底的宽禁带半导体电子市场占比呈现逐年增加的态势。在SiC衬底上外延生长高质量的宽禁带半导体材料是提高宽禁带半导体电子器件性能及可靠性的关键瓶颈。本文综述了近年来国内外研究者们在SiC衬底上外延SiC、氮化镓(GaN)、氧化镓(Ga₂O₃)所取得的研究进展,并展望了SiC衬底上宽禁带半导体外延的发展及应用前景。     

On Measuring Impurity Absorption Spectra of Semiconductors by Photoacoustic Spectroscopy

Theoretical relations are derived for the amplitude of the photoacoustic signal of a gas-coupled cell for thick semiconductor samples including the influence of multiple reflections of light within the sample. It is shown that in the range of low absorption coefficients characteristic of impurity absorption spectra the sensitivity of the cell can be enhanced by using a highly reflecting metal as backing material. Numerical estimates for CuInSe₂ are given to illustrate this effect.     

A Simple Model for Evaluation of Electronic Polarizabilities of Chalcopyrity Semiconductors

Simple correlations between the energy gap, optical electronegativity and the refractive index are given for some ternary chalcopyrite semiconductors. Refractive indices and electronic polarizabilities are evaluated. Results are in good agreement (±5.3%) with the experimental values, better than those of the valus (±19.5−28%) using bond charge model and plasma frequency formalism.     

Theory of Two-Beam X-Ray Diffractometry Method Using Synchrotron Radiation

Crystallography Reports - An accurate theory of the new method of two-beam X-ray diffractometry using synchrotron radiation has been developed. In this method, a beam from the source is reflected...     

Mineralization of Hydroxyapatite Induced by Eggshell As Calcium Source with Hydrothermal Synthesis Method

Crystallography Reports - Being no more use than fertilizer, eggshells are generally considered as garbage. A large number of eggshell wastes are produced from food processing, baking, and hatching...     

一步法制备纳米氧化锌的形成机理

以氯化锌和氢氧化钠为原料,采用直接水解一步法制备了针状和球形纳米氧化锌.借助于XRD、TEM等测试手段,对纳米氧化锌粉体的制备条件和其对粒度、形貌的影响进行了分析研究.利用负离子配位多面体生长基元理论模型,解释了直接水解合成氧化锌纳米晶体的形成机理和生长习性.研究结果表明,一步法直接合成纳米氧化锌的结晶过程遵循溶解-结晶-聚集生长机理模型;ZnO为极性晶体,具有极性生长特性,其成核过程包括均相成核和非均相成核.