Structural Stabilities of Ordered Nb4 Clusters on the Cu（111） and Cu（100） Surfaces

Based on first-principles calculations, we show that very high-density periodic arrays of Nb4 clusters with both the tetrahedron and quadrangle configurations can be stably absorbed on the Cu（111） and Cu（100） surfaces, with the quadrangle configurations more stable than the tetrahedron ones. The strong covalent bonding between atoms within the Nb4 clusters contributes to the stability of Nb4 adsorptions on the Cu surfaces. The energy barriers for the tetrahedron to the quadrangle-Nb4 on Cu（111） and （100） are around 1.21 eV and 0.94 eV/cluster, respectively. The stable adsorption of high-density Nb4 on these surfaces should have important applications.     

Temperature dependence of Cu20 orientations in the oxidation of Cu （111）/ZnO （0001） by oxygen plasma

The role of temperature on the oxidation dynamics of Cu20 on ZnO （0001） was investigated during the oxidation of Cu （111）/ZnO （0001） by using oxygen plasma as the oxidant. A transition from single crystalline Cu20 （111） orientation to micro-zone phase separation with multiple orientations was revealed when the oxidation temperature increased above 300 ~ C. The experimental results clearly show the effect of the oxidation temperature with the assistance of oxygen plasma on changing the morphology of Cu （111） film and enhancing the lateral nucleation and migration abilities of cuprous oxides. A vertical top-down oxidation mode and a lateral migration model were proposed to explain the different nucleation and growth dynamics of the temperature-dependent oxidation process in the oxidation of Cu （lll）/ZnO （0001）.     

Bi_（2．2）Sr_（1．8）Ca_（1．05）Cu（2．15－x）NaxO_

本文介绍了用熔融法制备Ｂｉ２．２Ｓｒ１．８Ｃａ１．０５Ｃｕ２．１５－ｘＮａｘＯ８＋ｙ（ｘ＝０，０．４～０．８）样品，发现诸样品零电阻温度都在９０Ｋ左右，其小ｘ＝０．７．Ｔｃ０达到９２，５Ｋ．在８１Ｋ较高温区，该类样品仍然表现出良好的超导电性，其临界电流密度还达到１０３Ａ／ｃｍ２量级．     

Cu（001）表面CO吸附的电子结构效应

本文应用Ｒｅｃｕｒｓｉｏｎ方法，计算了ＣＯ在Ｃｕ（００１）表面不同位置（顶位、桥位和空位）吸附的电子结构，分析了ＣＯ与Ｃｕ表面原子之间的键作用。分析表明ＣＯ在顶位吸附时，Ｃｐｘ（ｐｙ）－Ｃｕｄｓ（１号）和Ｃｐｘ（ｐｙ）－Ｃｕｄ２（ｄｓ）（２号）之间存在较强的键作用，这有利于ＣＯ在顶位吸附。桥位和空位吸附时，ＣＯ与表面原子形成的键较弱，是不稳定的。计算结果得到了实验的支持。     

ZnTe（ZnTe：Cu）多晶薄膜的XPS研究

用共蒸发法在室温下制备了ZnTe及ZnTe：Cu多晶薄膜，测量了电导率温度曲线，发现不掺杂的ZnTe薄膜的暗电导随温度的增加而线形增加，呈常规的半导体材料特征；掺Cu的ZnTe薄膜在温度较低时，lnσ随温度升高而缓慢增加，随后缓慢降低，达到一极小值，当温度继续升高时又陡然增加，呈现异常现象。用XPS研究了N2气氛下退火前后表面状态，发现不掺Cu的ZnTe薄膜呈现富Te现象。掺Cu后Te氧化明显，以ZnTe形式存在的Te明显减少；ZnTe：Cu薄膜中Zn的含量在退火前后变化明显，退火前，Zn主要以ZnTe形式存在，退火后Zn原子向表面扩散，使表面成分更加均匀，谱峰变宽；退火时，部分Cu原子进入晶格形成CuxTe相，引起载流子浓度变化，导致ZnTe：Cu多晶薄膜的电导温度关系异常。     

Atomic Diffusion in Cu/Si （111） and Cu/SiO2/Si （111） Systems by Neutral Cluster Beam Deposition

The Cu films are deposited on two kinds of p-type Si （111） substrates by ionized duster beam （ICB） technique. The interface reaction and atomic diffusion of Cu/Si （111） and Cu/SiO2/Si （111） systems are studied at different annealing temperatures by x-ray diffraction （XRD） and Rutherford backscattering spectrometry （RBS）. Some significant results are obtained： For the Cu/Si （111） samples prepared by neutral dusters, the interdiffusion of Cu and Si atoms occurs when annealed at 230℃. The diffusion coefficients of the samples annealed at 230℃ and 500℃ are 8.5 ×10^-15 cm^2.s^-1 and 3.0 ×10^-14 cm^2.s^-1, respectively. The formation of the copper-silicide phase is observed by XRD, and its intensity becomes stronger with the increase of annealing temperature. For the Cu/SiO2//Si （111） samples prepared by neutral dusters, the interdiffusion of Cu and Si atoms occurs and copper silicides are formed when annealed at 450℃. The diffusion coefficients of Cu in Si are calculated to be 6.0 ×10^-16 cm^2.s^-1 at 450℃, due to the fact that the existence of the SiO2 layer suppresses the interdiffusion of Cu and Si.