Ge基GaInP材料结构和光学性质研究

采用高分辨透射电子显微图像(HRTEM)、光致发光谱(PL)和原子力显微镜(AFM)技术等研究了金属有机化学气相沉积(MOVPE)技术制备的Ge基Ga In P异质外延层的结构和光学性质.研究表明,Ga In P带边发光峰能量位置随温度变化的倒"S"型变化来源于局域态和本征态发光之间的竞争;同时,实验中观察到了由[Ge(Ga,In)-V(Ga,In)]络合物所引起的1.4 e V左右的宽发光峰.不同偏角衬底的Ga In P外延层的变温PL谱和AFM分析表明,9°偏角的Ge衬底上生长的Ga In P外延层的有序度比6°偏角时减小,表面形貌更为平整.此外,Ge衬底和Ga In P之间插入超薄Al As层会增加Ga In P材料的有序度.当Al As界面层厚度由0.5 nm增加到5 nm时,观察到了由于应力增加所导致的Ga In P材料有序度的增加,从而导致载流子弛豫时间增加且呈双指数规律衰减.在Ge/Al As/Ga In P结构中,100 K下的PL谱中出现了与P空位相关的1.57 e V左右宽发光峰,并且该发光峰强度随Al As界面层厚度的增加而增强.     

In、Ga掺杂SnO_2的第一性原理研究

基于密度泛函理论的第一性原理平面波超软赝势方法,建立了本征SnO_2、SnO_2∶In、SnO_2∶Ga和SnO_2∶(In,Ga)超晶胞模型并进行了几何结构优化,对其能带结构、态密度、电荷密度及光学性质进行了模拟计算.结果显示,与SnO_2∶In和SnO_2∶Ga相比,SnO_2∶(In,Ga)的晶格常数更接近于本征SnO_2,可有效降低SnO_2材料掺杂体系的晶格畸变.SnO_2中In、Ga的掺入能够增大材料的带隙值,且能带结构向高能方向移动,材料呈现典型的p型半导体特性.SnO_2∶(In,Ga)中,In与Ga掺杂原子和O原子的电子云呈现出共价键特性.光学性能表明,SnO_2∶(In,Ga)晶体中,光子能量在0~2.45 e V和大于6.27 e V的范围内表现出良好的介电性能,在微型微电子传感器机械系统器件和高密度信息存储等方面具有良好的应用前景.SnO_2∶(In,Ga)在可见光范围内具有10~5cm~(-1)数量级的吸收系数,能够强烈地吸收光能,在光电器件的吸收材料中具有潜在的应用前景.     

In、Ga掺杂对SnO2的第一性原理研究

基于密度泛函理论的第一性原理平面波超软赝势方法，建立了本征SnO2、SnO2:In、SnO2:Ga和SnO2:(In,Ga) 超晶胞模型并进行了几何结构优化，对其能带结构、 态密度、 电荷密度及光学性质进行了模拟计算. 结果显示，相比于SnO2:In和SnO2:Ga，SnO2:(In, Ga)的晶格常数更接近于本征SnO2，可有效降低SnO2材料掺杂体系的晶格畸变. SnO2中In、Ga的掺入能够增大材料的带隙值，且能带结构向高能方向移动，材料呈现典型的p型半导体特性. SnO2:(In, Ga)中，In与Ga掺杂原子和O原子的电子云呈现出共价键特性. 光学性能表明，SnO2:(In, Ga)晶体中，光子能量在0~2.45eV和大于6.27eV的范围内表现出良好的介电性能，在微型微电子传感器机械系统器件和高密度信息存储等方面具有良好的应用前景. SnO2:(In, Ga)在可见光范围内具有105cm-1数量级的吸收系数，能够强烈地吸收光能，在光电器件的吸收材料中具有潜在的应用前景.     

InGaN太阳能电池材料的辐射性质

对采用分子束外延生长的In1-xGaxN薄膜与金属有机化学气相沉积生长的GaAs和Ga0.51In0.49P薄膜太阳能电池材料进行了对比研究,探讨了全太阳光谱材料系In1-xGaxN合金薄膜受到高能粒子辐射后的电学特性变化规律。实验结果显示:GaAs和Ga0.51In0.49P的光致发光信号强度受到照射的强烈压制,而受到类似剂量照射后InN的光致发光信号强度没有下降;In1-xGaxN合金薄膜材料的电学特性表现出用高能质子(2MeV)照射比当前常用的GaAs和GaInP光伏材料有更高的电阻。这表明,In1-xGaxN对高能粒子损伤没有GaAs和GaInP那么敏感,从而给空间受到强辐射的高效太阳能电池提供了巨大的应用潜力。     

ZnSe和CuXSe2(X=Al,Ga,In)结构和光学性质的研究

利用赝势平面波基组的密度泛函理论方法,首先优化太阳能材料ZnSe和CuXSe_2(X=Al,Ga,In)的晶体结构,得到晶格参数、键长,并预测了CuXSe_2带隙和光学性质,带隙按照Al→Ga→In依次减小,但晶格参数和形变参数依次增加;通过光学性质中介电函数、吸收系数,反射率和光电导率分析发现,吸收系数的最强峰都在紫外区域,在3种晶体中光学性能按照Al→Ga→In依次增强。     

InAs/GaAs/InP及InAs/InP自组装量子点室温PL谱的研究

用五带 k· p模型计算 In As/ Ga As/ In P及 In As/ In P的室温 PL谱的能级分布 ,分析PL谱峰值 .发现 Ga As的张应变层影响 PL峰值位置 ,与 In As/ In P量子点相比 ,In As/Ga As/ In P量子点 PL谱峰值有明显红移 ,并从能带理论给出解释     

粉煤灰中稀有金属镓-铌-稀土的联合提取

 采用碱法烧结-分步浸出法, 对重庆安稳电厂循环流化床粉煤灰中Ga、Nb、REE 等稀有金属进行了联合提取实验。结果表明, 粉煤灰加无水碳酸钠在860℃下烧结30 min, 采用水浸法提取Ga, 采用酸浸法提取REE, Ga、REE 的提取率分别达到84.70%和80.07%;Nb 在两步浸出实验中的浸出率均低于1%, 但在酸浸滤渣中得到富集。采用D201 离子交换树脂和NH₄Cl(0.5 mol/L)溶液在40℃下对富Ga 水浸滤液中的Ga 进行吸附与解吸附, Ga 的吸附率(27.99%)、解吸附率(37.33%)偏低, 可能与解吸附液用量不足和水浸滤液中Al 离子竞争吸附有关, 后续将通过改进实验条件提升Ga 的分离提取效果;酸浸液中REE 及酸浸渣中Nb 的分离提取工艺尚需进一步研究。通过上述稀有金属Ga、Nb、REE 的联合提取及后续工作, 可实现安稳电厂粉煤灰的高附加值利用, 有效缓解粉煤灰造成的环境污染。     

半导体激光器短电脉冲调制光脉冲的产生与控制

对半导体激光器短电脉冲调制增益开关法产生皮秒光脉冲动力学过程进行理论分析和实验研究 .基于单模数率方程 ,采用相图 ( Phase Portraits)法分析激光器激射皮秒光脉冲时载流子浓度和光子密度变化的对应关系 .探讨直流参数、调制脉冲参数和器件寄生参量等对产生皮秒光脉冲的影响 .在此基础上 ,研究 In Ga As P/ In P激光器短电脉冲调制产生单发激光脉冲最佳的实验条件     

全In组分可调InGaN的分子束外延生长

Ⅲ族氮化物InxGa1-xN合金为直接带隙半导体,其禁带宽度随着In组分变化从3.43 e V(Ga N)到0.64e V(In N)连续可调,波长范围覆盖了0.3–1.9μm,具有电子饱和速度高和光学吸收系数大等特点,是制备高效率全光谱太阳能电池和白光照明器件的理想材料.由于缺少合适的衬底,In N和InxGa1-xN薄膜通常生长在蓝宝石或Ga N模板上.本论文综述了采用MBE方法,在蓝宝石衬底和Ga N模板上生长了In N和全组分InxGa1-xN薄膜的生长行为和材料物理性质.利用MBE边界温度控制法在蓝宝石衬底上生长高室温电子迁移率的InN薄膜,利用温度控制外延法在Ga N/蓝宝石模板上制备了全组分InxGa1-xN薄膜.     

焊料Sn3.5Ag4Ti(Ce,Ga)与SiO_2基板低温活性焊接机理

采用扫描电镜、能谱仪和透射电镜研究了Sn3.5Ag4Ti(Ce,Ga)低温活性焊接SiO_2基板界面的微观形貌和焊接机理,并根据反应热力学和活性元素的吸附理论分析了Sn3.5Ag4Ti(Ce,Ga)与SiO_2基板的焊接机理及焊接动力学过程.实验结果表明,焊接界面由Ti Si和Ti O_2形成.理论分析与实验结果一致表明:Ti元素在SiO_2基板表面的化学吸附可能是实现焊接润湿的主要原因,在焊接的初始阶段发挥重要的作用;Ti与SiO_2之间的界面反应并形成界面产物是实现Sn3.5Ag4Ti(Ce,Ga)与SiO_2基板焊接的主要机理.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with