CdSxTe1-x多晶薄膜的制备与性质研究

采用真空共蒸发方法制备了CdSxTe1 -x 多晶薄膜 ,并用原子力显微镜、x射线衍射和光学透过率谱等研究了CdSxTe1 -x多晶薄膜的结构和性质 .结果表明 :薄膜均匀、致密、无微孔 ,当x≥ 0 5时为n型半导体 ,x <0 5时为p型半导体 .CdSxTe1 -x多晶薄膜的光学能隙随x变化 .结合薄膜的晶格常数和光学能隙得到了薄膜发生相变的组分 ,当x<0 2 5时CdSxTe1 -x 多晶薄膜为立方相 ,当x >0 2 5时为六方结构 .退火后结构没有改变 ,能隙减小 .提出了用CdSxTe1 -x多晶薄膜作为缓冲层的新型结构太阳电池 .     

A New Method to Prepare Boron Nitride Thin Films

We report a new method to prepare boron nitride (BN) thin films on Si (100) substrates in an Ar-N2-BCl3-H2 gas system by magnetron arc enhanced plasma chemical vapour deposition. Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) are used to characterize the films. The FTIR spectra show that the deposited boron nitride films experienced a transition from pure h-BN phase to a cubic-containing phase with the variation of arc current ranging from IOA to 18A. The BN film with 42% c-BN was obtained without substrate bias voltage. In the gas system of Ar-N2-BCl3-H2, h-BN can be preferentially etched by chlorine. The chemical etching effect of chlorine allows the formation of c-BN without substrate bias voltage, which may develop a new perspective for the deposition of high quality c-BN film with low stress.     

Self-Assembly of Gold Nanoparticles on Nanometre-Patterned Surface

The self-assembly processes of gold nanoparticles on nanometre-step-patterned Si surface and polished Si surface are investigated by the convective self-assembly method. The convective self-assembly method is used to deposit the colloids dispersed in benzene onto the substrates. The SEM results show that the configurations of the gold arrays depend on the surface morphology of the substrates. On the nanometre-step-patterned Si surface, the nanoparticles self assemble into parallel lines, and the distance between the neighbouring lines is around 35 nm. On the polished Si surface the nanoparticles form compact domains. In each domain the particles are closepacked in a two-dimensional hexagonal superlattice and are separated by uniform distances. The analysis shows that on the nanometre-step-patterned Si surface, the steps play critical roles in the self-assembly process of gold nanoparticles. The capillary force from the steps drives the particles to lines along the steps. Therefore, the particles tend to self-assemble into one-dimensional line structures when the solvent evaporates. For the polished Si substrate there is a little difference that the particles form two-dimensional hexagonal superlattices without the directional confinement.     

CdSxTe1-r多晶薄膜的制备与性质研究

采用真空共蒸发方法制备了CdSxTe1-x多晶薄膜,并用原子力显微镜、x射线衍射和光学透过率谱等研究了CdSxTe1-x多晶薄膜的结构和性质.结果表明薄膜均匀、致密、无微孔,当x≥0.5时为n型半导体,x＜0.5时为p型半导体.CdSxTe1-x多晶薄膜的光学能隙随x变化.结合薄膜的晶格常数和光学能隙得到了薄膜发生相变的组分,当x＜0.25时CdSxTe1-x多晶薄膜为立方相,当x＞0.25时为六方结构.退火后结构没有改变,能隙减小.提出了用CdSxTe1-x多晶薄膜作为缓冲层的新型结构太阳电池.     

具有高阻抗本征SnO2过渡层的CdS/CdTe多晶薄膜太阳电池

采用超声喷雾热解法制备了具有高阻抗的本征SnO2透明导电膜,将其运用在CdS层减薄了的CdS/CdTe多晶薄膜太阳电池中,对减薄后的CdS薄膜进行了XRD,AFM图谱分析,并对电池进行了光、暗I-V,光谱响应和C-V测试.结果表明,在高阻膜上沉积的减薄CdS薄膜(111)取向更明显,但易形成微孔.引入高阻层后,能消除CdS微孔形成的微小漏电通道,有效保护p-n结,改善了电池的并联电阻、填充因子和短波响应,使载流子浓度增加,暗饱和电流密度减小,从而电池性能得到改善,电池转换效率增加了14.4%.     

钐钴永磁合金吸放氢特性及应用研究进展

钐钴永磁合金因卓越的磁性能、优异的高温性能和耐蚀性得到了广泛应用。随着在航空航天,风力发电等行业对高性能钐钴永磁合金需求加强,开发高性能钐钴永磁合金一直是本领域的研究热点。采用吸氢破碎制备单晶磁粉为制备高性能钐钴永磁合金的发展提供了新思路,同时,为了满足氢气服役环境对钐钴永磁合金高温耐氢能力的要求,开发强耐氢钐钴永磁合金的需求日趋迫切,因此需加强钐钴永磁材料吸放氢动力学与热力学机制的认识与了解,以指导研究钐钴合金吸氢破碎和强耐氢合金。本文首先介绍了合金吸放氢动力学与热力学研究中常用的检测与分析方法,然后综述了SmCo₅, Sm₂Co₇和Sm₂Co₁₇合金吸放氢过程中的结构变化和动力学与热力学研究进展,接着对近年来钐钴永磁材料吸氢破碎应用的研究成果进行了总结与讨论,最后对开发易氢破和强耐氢钐钴永磁合金作了展望。     

谱参数保形变换对称性

本文讨论了O(3)非线性σ模型在对偶变换下的对称性,探讨了生成函数变换的根源;证实该模型中具有无穷保形对称性;得到了基本场的无穷维李代数结构及两种代数间的半直积关系;最后给出了相应的Bianchi-Backlund变换.     

超主手征场模型中的无穷保形对称性和Riemann-Hilbert变换

我们在超主手征场模型中找到了一种新的对称变换——C变换,发现在这种变换下体系具有一个与没有中心项的Virasoro代数相关的无穷维李代数.利用Riemann-Hilbert变换,我们探讨了C变换的物理根源.     

Effective anisotropy and coercivity in nanocrystalline single-phase NdFeB permanent magnetic material

The effect of exchange-coupling interaction on the effective anisotropy and its varying tendency in nanocrystalline single-phase NdFeB permanent magnetic material have been investigated. The results show that the exchange-coupling interaction between grains makes the effective anisotropy of material, Keff, decrease with the reduction of grain size. The variation of Keff is basically the same as that of coercivity. The decrease in effective anisotropy is the main reason of the reduction of coercivity for nanocrystalline single-phase NdFeB permanent magnetic material. In order to get high anisotropy and coercivity in nanocrystalline single-phase NdFeB permanent material, the grain size should be larger than 35 nm.