Self-Assembly of Micro-Parts onto Si Substrates at Liquid-Liquid Interface

We report a new approach for the self-assembly of cuboid micro-parts onto Si substrates to construct three-dimensional microstructures. To perform assembly, the Si substrates are prepared with a deep cavity array as binding sites. An aggregate composed of hundreds of uniformly aligned micro-parts is formed at the C10F18-H2O interface. The micro-parts are arranged by passing the substrate through the aggregate of micro-parts, thus the micro-parts are left on the substrate, and then the substrate is vibrated ultrasonically in the solution, making it possible for the micro-parts to fall into the cavities on the substrate. Finally the substrate is pulled out of the solution after assembly. This technique could give a high yield of up to 70%, providing a new method for micro-assembly.     

Reduction of Dislocations in GaN Epilayer Grown on Si （111） Substrates using a GaN Intermedial Layer

GaN intermedial layers grown under different pressures are inserted between GaN epilayers and AIN/Si（111） substrates. In situ optical reflectivity measurements show that a transition from the three-dimensional （3D） mode to the 2I） one occurs during the GaN epilayer growth when a higher growth pressure is used during the preceding GaN intermedial layer growth, and an improvement of the crystalline quality of GaN epilayer will be made. Combining the in situ reflectivity and transmission electron microscopy （TEM） measurements, it is suggested that the lateral growth at the transition of growth mode is favourable for bending of dislocation lines, thus reducing the density of threading dislocations in the epilayer.     

宽能带隙电子器件

硅集成电路和数据存贮是两种最成功的技术，目前，这两种技术继续以高速度发展。在集成电路技术中，按照摩尔定律，一块芯片上的晶体管数目每隔18个月就会翻一翻。而对于磁盘驱动技术，自1991年起磁头的总体位密度以每年60％至100％的速率增加。集成电路是通过对半导体应用电场控制载流子流动来工作的，因此关键的参数是电子或空穴上的电荷。而在磁性数据存贮中关键的参数是电子的自旋。     

X光光电子能谱法测定胶片中氟,硅和铝的研究

应用Ｘ光光电子能谱法测定了几种彩色胶片表面层中氟的１ｓ能级的结合能；分别比较了水处理前后、溅蚀前后胶片护膜层氟的变化，表明氟化物分布在护膜最表层，是一种易溶于水的氟化物；测定了彩色片护膜层所含硅２ｐ能级的结合能，与自制彩色片护膜层测定结果比较，优质片含一种较多负电性，用与自制片的无机硅不同的硅化物作毛面剂；对溅蚀前后优质片和自产彩色片中的硅铝比变化进行比较，提出优质彩色片Ｆ－４００的护膜层可能是双     

荧光XAFS研究Si可稀浓度杂质的区域结构

荧光ＸＡＦＳ研究Ｓｉ晶体中等电子，缺电子和富电子杂质原子的区域环境结构。结果表明杂质原子的电子构型决定了杂质原子对Ｓｉ区域晶格形变的影响。相对于共价键长ＲＳｉ－Ｓｉ（０．２４０ｎｍ）来说，富电子杂质Ａｓ导致Ｓｉ晶格在Ｓｉ（１１１）方向的ＲＡｓ－Ｓｉ键长产生０．００４ｎｍ的反应增长，等电子杂质Ｇｅ的Ｒ－Ｇｒｅ－Ｓｉ和缺电子杂质Ｇａ和ＲＧａ－Ｓｉ键长收缩０．００２ｎｍ。     

手性噻唑烷-铑(I)配合物催化的苯乙酮不对称硅氢化反应

由L-半胱氨酸甲酯与α-吡啶甲醛缩合制备了2-(α-吡啶基)-4-羧甲基-1, 3-噻唑烷手性配体。用该手性配体与[Rh(COD)]2反应原位生成的Rh(I)配合物为催化剂进行了苯乙酮的不对称硅氢化反应。反应的化学产率达91%, 光学产率达82.1%e.e.。考察了各种反应条件对催化剂性能的影响。     

A Novel Method to Synthesize Polyorganozircosilazane

A new kind of polyorganozircosilazane as Si/Zr/C/N-based ceramic precursor was synthesized from the condensation reaction of hexamethyleyclotrisilazane lithium salts(D3^NLi）and zirconium tetrachloride(ZrCl4).In the presence of N,N,N’,N’-tetramethyl ethylene diamine(TMEDA),polyorganozircosilazane was obtained in high yield.