铁（Ⅲ）的三元离子缔合物与镓（Ⅲ）、铋（Ⅲ）、铑（Ⅲ）和铟（Ⅲ）的浮选分离

分光光度法研究了四丁基溴化铵-硫氰酸铵体系浮选分离和富集F e（Ⅲ）的行为及与一些金属离子分离的条件。结果表明,在一定条件下,能使F e（Ⅲ）与G a（Ⅲ）,B i（Ⅲ）,R h（Ⅲ）和In（Ⅲ）分离。     

Surface diffusion of Si,Ge and C adatoms on Si （001） substrate studied the molecular dynamics simulation

Depositions of Si, Ge and C atoms onto a preliminary Si (001) substrate at different temperatures are investigated by using the molecular dynamics method. The mechanism of atomic self-assembling occurring locally on the flat terraces between steps is suggested. Diffusion and arrangement patterns of adatoms at different temperatures are observed. At 900 K, the deposited atoms are more likely to form dimers in the perpendicular [110] direction due to the more favourable movement along the perpendicular [110] direction. C adatoms are more likely to break or reconstruct the dimers on the substrate surface and have larger diffusion distances than Ge and Si adatoms. Exchange between C adatoms and substrate atoms are obvious and the epitaxial thickness is small. Total potential energies of adatoms and substrate atoms involved in the simulation cell are computed. When a newly arrived adatom reaches the stable position, the potential energy of the system will decrease and the curves turns into a ladder-like shape. It is found that C adatoms can lead to more reduction of the system energy and the potential energy of the system will increase as temperature increases.     

在Si（111）—（7×7）表面自组织生长二维Ge团簇超晶格

利用超高真空扫描隧道显微镜研究了室温条件下亚单层Ge在Si(111)-(7×7)表面上的自组织生长.通过控制Ge的沉积量,在Si(111)-(7×7)表面上自组织生长成一种具有六重对称性的二维Ge团簇超晶格.构成超晶格的Ge团簇均位于(7×7)亚单胞的位置上,而且它们的形状和大小基本保持一致.文中对这种自组织结构的形成机理进行了讨论.     

Growth of Mn5Ge3 ultrathin film on Ge（111）

The growth of Mn5Ge3 ultrathin films with different thicknesses, prepared by solid phase epitaxy, is studied. The results of scanning tunnelling microscopy and low energy electron diffraction studies show that the film can be formed and it is terminated with a （√3 × √3） R30° surface reconstruction when the thickness of Mn exceeds 3 monolayers. The magnetic properties show that the Curie temperature is about 300 K and the T^2-dependent behaviour is observed to remain up to 220 K.     

MBE Growth of Highly Relaxed Si0.45 Ge0.55 Films with Very Low Misfit Dislocation Density on Si （001） Substrates

We investigate the molecular-beam-epitaxy growth of highly relaxed Si0.45 Ge0.55 films with very low dislocation densities. By using the Si3N4 film as the mask material, the Si0.45Ge0.55 film can be grown on a compositionally stepwise graded SiGe buffer layer in 3 μm× 3 μm windows on a Si （001） substrate. Raman scattering spectroscopy measurement shows that more than 90% strain of the Si0.45Ge0.55 film is relaxed, and almost neither misfit dislocation lines nor etch pits of thread dislocations could be observed when the sample is etched by the modified Schimmel etchant. We suggest that the results can be explained by influence of the edge-induced strain relaxation of the epitaxial film and the edge-induced stress of the mask material.     

Effects of high temperature rapid thermal annealing on Ge films grown on Si（001） substrate

Tensile strain,crystal quality,and surface morphology of 500 nm thick Ge films were improved after rapid thermal annealing at 900 C for a short period(20 s).The films were grown on Si(001)substrates by ultra-high vacuum chemical vapor deposition.These improvements are attributed to relaxation and defect annihilation in the Ge films.However,after prolonged(20 s)rapid thermal annealing,tensile strain and crystal quality degenerated.This phenomenon results from intensive Si–Ge mixing at high temperature.     

Radiation acceptors in GeSi alloys

The Hall-effect, conductivity, isochronal and isothermal annealing of defects in n-type Gez.sbnd;Si alloys irradiated by electrons and

-quantum are investigated. Maximum content of minority component was equal to 1,5 at .% Si. It is shown that in Gez.sbnd;Si three types of radiation acceptors are being generated. The energetic parameters of defects, their dependence on the content of Si in Gez.sbnd;Si are calculated. The effect of radiation acceptors on the change of carriers concentration and mobility in Gez.sbnd;Si is investigated.     

形变Si,Ge中的深能级

对生长在合金衬底上的形变Si或Ge中由替位原子或空位缺陷产生的深能级进行了研究。其中形变体材料的电子结构用经验的紧束缚方法进行计算,缺陷能级采用格林函数法进行计算出。结果表明,晶格中的形变使原来类p的T₂能级发生分裂,其数值随形变的增加而增大。形变还造成Si和Ge的价带顶有较大的上升,从而使某些杂质的缺陷能级由深能级变为共振能级。 关键词：     

Ge/Si(111)与Si/Ge(111)体系的生长特性与表面再构研究

本文利用RHEED和AES对Ge/Si(111)和Si/Ge(111)体系的生长特性与表面再构进行了研究。由此提出了其生长模式,并讨论了应力对生长特性、界面特性和表面再构的作用。     

Formation and local electronic structure of Ge clusters on Si（111）-7×7 surfaces

We report the formation and local electronic structure of Ge clusters on the Si(111)-7$\times $7 surface studied by using variable temperature scanning tunnelling microscopy (VT-STM) and low-temperature scanning tunnelling spectroscopy (STS). Atom-resolved STM images reveal that the Ge atoms are prone to forming clusters with 1.0~nm in diameter for coverage up to 0.12~ML. Such Ge clusters preferentially nucleate at the centre of the faulted-half unit cells, leading to the `dark sites' of Si centre adatoms from the surrounding three unfaulted-half unit cells in filled-state images. Bias-dependent STM images show the charge transfer from the neighbouring Si adatoms to Ge clusters. Low-temperature STS of the Ge clusters reveals that there is a band gap on the Ge cluster and the large voltage threshold is about 0.9~V.     

La（Ⅲ）,Gd（Ⅲ）,Tb（Ⅲ）8—羟基喹啉固体配合物的光声光谱与 …

本文合成Ｌａ（Ⅲ）、Ｇｄ（Ⅲ）、Ｔｂ（Ⅲ）８－羟基喹啉固体配合物，通过对其光声光谱的分析，研究了８－羟基喹啉稀土配合物的荧光性质和驰豫过程。     

Structural transformation of Ge dimers on Ge（001） surfaces induced by bias voltage

Scanning tunnelling microscopy is utilized to investigate the local bias voltage tunnelling dependent transformation between （2×1） and c（4×2） structures on Ge（001） surfaces, which is reversibly observed at room temperature and a critical bias voltage of -0.80 V. Similar transformation is also found on an epitaxial Ce islands but at a slightly different critical bias voltage of -1.00V. It is found that the interaction between the topmost atoms on the STM tip and the atoms of the dimers, and the pinning effect induced by Sb atoms, the nacancies or the epitaxial clusters, can drive the structural transformation at the critical bias voltage.     

Intermixing-controlled epitaxy for Si–Ge heterostructure devices

To fabricate high quality SiGe/Si heterostructures, control of intermixing between Si and Ge is essential during crystal growth. This paper describes the recent progress of ‘intermixing-controlled epitaxy’. A combined method of MBE (molecular beam epitaxy) and SPE (solid-phase epitaxy) was developed and used to fabricate a new heterostructure (n-Si_0.8Ge_0.2/Si channel/Si_1 − xGe_xbuffer layer/Si substrate). Observation by TEM demonstrated that the hetero-interface obtained by SPE was atomically flat. This interface provides the ultrahigh mobility of a two-dimensional electron gas (2DEG). In addition, the influence of atomic-hydrogen irradiation during MBE on Ge dispersion in the SiGe mixed crystal is examined. Results indicate that the number of Ge–Ge pairings was decreased by hydrogen irradiation. Such a decrease deformed the local symmetry of the Si–Ge bond from tetrahedral symmetry. As a result, photoluminescence intensity was sucessfully increased.     

高压下的Ge和Si的相变

 本文采用赝势方法研究Ⅳ族元素Ge和Si宰高压下的共价键－金属相相变，计算了状态方程、相平衡压力、体积跃变量及其金属相的超导临界温度。结果表明，理论与实验符合都比较好。     

A k·p analytical model for valence band of biaxial strained Ge on（001） Si1-xGex

In this paper,the dispersion relationship is derived by using the k·p method with the help of the perturbation theory,and we obtain the analytical expression in connection with the deformation potential.The calculation of the valence band of the biaxial strained Ge/（001）Si1-xGex is then performed.The results show that the first valence band edge moves up as Ge fraction x decreases,while the second valence band edge moves down.The band structures in the strained Ge/（001）Si 0.4 Ge 0.6 exhibit significant changes with x decreasing in the relaxed Ge along the [0,0,k] and the [k,0,0] directions.Furthermore,we employ a pseudo-potential total energy package（CASTEP） approach to calculate the band structure with the Ge fraction ranging from x = 0.6 to 1.Our analytical results of the splitting energy accord with the CASTEP-extracted results.The quantitative results obtained in this work can provide some theoretical references to the understanding of the strained Ge materials and the conduction channel design related to stress and orientation in the strained Ge pMOSFET.     

形变超晶格Si/Ge的能带结构

用经验的紧束缚方法对短周期的(Si)_n/(Ge)_m形变超晶格的电子态进行了计算。结果表明,由于布里渊区折迭的要求,只有当n+m=10时超晶格才可能产生直接能隙。对周期为n+m=10的超晶格,Γ,N,△处的导带谷间的相对位置对直接能隙的形成具有决定作用,而n的大小与衬底的组分对此有极大影响。(Si)₆/(Ge)₄和(Si)₈/(Ge)₂超晶格在Si_1-xG 关键词：     

Phase transitions and magnetocaloric effects in intermetallic compounds MnFeX（X=P,As,Si,Ge）

Since the discovery of giant magnetocaloric effect in MnFeP1-x As x compounds,much valuable work has been performed to develop and improve Fe2P-type transition-metal-based magnetic refrigerants.In this article,the recent progress of our studies on fundamental aspects of theoretical considerations and experimental techniques,effects of atomic substitution on the magnetism and magnetocalorics of Fe2P-type intermetallic compounds MnFeX(X=P,As,Ge,Si) is reviewed.Substituting Si(or Ge) for As leads to an As-free new magnetic material MnFeP1-xSi(Ge)x.These new materials show large magnetocaloric effects resembling MnFe(P,As) near room temperature.Some new physical phenomena,such as huge thermal hysteresis and ’virgin’ effect,were found in new materials.On the basis of Landau theory,a theoretical model was developed for studying the mechanism of phase transition in these materials.Our studies reveal that MnFe(P,Si) compound is a very promising material for room-temperature magnetic refrigeration and thermo-magnetic power generation.     

Si基Ge异质结构发光器件的研究进展

近年来,与Si的CMOS工艺相兼容的Ge/Si异质结构发光器件取得很多重要的进展。本文概述了Si基Ge异质结构发光器件的最新成果,如Ge/Si量子点发光二极管、Si衬底上的Ge发光二极管及激光器和Ge/SiGe多量子阱发光二极管,分别描述了这些器件的特点和增强其发光特性的途径。最后展望了Si基Ge异质结构发光器件的发展趋势,指出尽管Si基Ge异质结构发光器件获得了很大的发展,但是器件的发光效率仍然很低,离实用还有一定距离,还需要在材料和器件的结构方面有更多的创新。     

钐（Ⅲ）,铽（Ⅲ）与色氨酸和苯丙氨酸配合物的光声光谱研究

合成了Ｌｎ（Ｔｒｐ（３Ｃｌ３．Ｈ２Ｏ和Ｌｎ（Ｐｈｅ）Ｃｌ３．５Ｈ２Ｏ（Ｌｎ＾３＋为Ｓｍ＾３＋，Ｔｂ＾３＋）固体配合物微晶，在３００－７００ｎｍ测定并解释了配合物的光声光谱。从无辐射跃迁角度研究芳香氨基酸固体配合物的能级状况和分子内能量传递过程。结合荧光光谱研究了芳香氨基酸固体配合物的发光特性，并建立了激发驰豫模型。