The electrical, optical properties of AlSb polycrystalline thin films deposited by magnetron co-sputtering without annealing

In order to fabricate AlSb polycrystalline thin films without post annealing, this paper studies a technology of magnetron co-sputtering onto intentionally heated substrate. It compares the structural characteristics and electrical properties of AlSb films which are deposited at different substrate temperatures. It finds that the films prepared at a substrate temperature of 450 oC exhibit an enhanced grain growth with an average grain size of 21 nm and the lattice constant is 0.61562 nm that goes well with unstained lattice constant (0.61355 nm). The ln(σ_dark) ～1/T curves show that the conductivity activation energy is about 0.38 eV when the film is deposited at 450 oC without an annealing. The transmittance and reflectance spectra show that the film deposited at 450 oC has an optical band gap of 1.6 eV. These results indicate that we have prepared AlSb polycrystalline films which do not need a post annealing.     

CdSexS1-x电子学结构及光学性质的第一性原理研究

CdSe是Ⅱ-Ⅵ族中重要的半导体材料,一定条件下可与CdS形成无限固溶体CdSexS1-x(0≤x≤1)。CdSexS1-x在薄膜太阳电池及光电器件等领域具有重要的应用,对CdSexS1-x的电子学结构和光学性质进行研究有助于进一步提高其在光电器件等方面的应用。基于第一性原理,采用平面波超软赝势方法,计算了CdSexS1-x的电子学结构及光学性质,并将计算结果与实验进行了对比。结果表明,CdSexS1-x的晶格常数随着Se组分的增加呈线性增大趋势,态密度向低能级方向移动,禁带宽度减小,光吸收边发生一定程度的蓝移。当Se含量为0.5时,CdSexS1-x的光折射、反射和能量损失最大。除了Se和S的比例为1∶1时CdSexS1-x所属晶系为三斜晶系,其他比例下均为立方晶系。理论计算结果与实验符合。     

黄芪药渣中阿拉伯木聚糖(AX-Ⅰ-1)的提取纯化、结构分析及体外抗氧化作用

黄芪药渣经分级提取,再通过二乙氨乙基(DEAE)-纤维素52阴离子交换柱层析和Sephacryl S-400HR凝胶柱层析分离纯化,得到4个多糖组分AX-Ⅰ-1~AX-Ⅰ-4.对多糖AX-Ⅰ-1的理化性质和结构进行研究发现,AX-Ⅰ-1含有鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖(摩尔比为0.006∶14.113∶8.284∶0.116∶0.468∶1),主链由阿拉伯糖和木糖通过β-(1→2),(1→3)和(1→4)苷键组成,支链由(1→4)βArap,(1→3)βGalp和(1→2)βMan组成,非还原末端由αRhap,βGclp和βGalp组成.对多糖AX-Ⅰ-1~AX-Ⅰ-4的抗氧化研究结果表明,这4个组分对羟基自由基、超氧阴离子自由基和1,1-二苯基-2-三硝基苯肼(DPPH)自由基均有一定的清除作用;当浓度为0.1 mg/m L时,多糖AX-Ⅰ-2~AX-Ⅰ-4对超氧阴离子的清除率是阳性对照维生素C(Vc)的2倍.