GaSb晶体的高能N~＋注入及其光学性质

本文用低温光致发光光谱（ＰＬ）、椭圆偏振光谱（ＳＥ）、背散射及沟道技术（ＲＢＳ／Ｃ）、扫描电镜技术（ＳＥＭ）等研究了２ＭｅＶ高能Ｎ＋注入Ｇａｓｂ晶体损伤及其光学性质．结果表明高能Ｎ＋注入Ｇａｓｂ晶体不会产生反常膨胀（Ｓｗｅｌｌｉｎｇ），通过合理的退火可使注入样品晶格得到很好恢复．椭圆偏振光谱能准确反映注入样品晶格损伤情况，并与背散射结果吻合．用有效介质模型（ＥＭＡ）对椭偏谱进行似合可对注入损伤有定量的了解．     

用ECR-PECVD低温沉积多晶硅薄膜

在自行设计研制的先进的电子回旋共振（ECR）等离子体增强化学气相沉（PECVD）装置上,采用ECR-PECVD可控活化低温外延技术,以SiH4＋H2为气源,硅和普通玻璃为衬底,低温（小于等于550℃）制备多晶硅（poly-Si）薄膜。利用反射高能电子衍射、透射电子显微镜和原子力显微镜研究了SiH4流量、H2流量和衬底温度等工艺参数的改变对薄膜晶化的影响。通过分析薄膜结构和形貌,得出适宜低温生长多晶硅薄膜的工艺参数。     

[(BaTiO3)m/(SrTiO3)m]n超晶格生长的RHEED实时研究

利用反射高能电子衍射(RHEED)，研究了在SrTiO3(100)基片上采用激光分子束外延法生长的[(BaTiO3)m／(SrTiO3)m]n超晶格薄膜的生长特性。观察到清晰明亮的反射高能电子衍射花样及富有周期性的RHEED振荡曲线，制备的超晶格呈现良好的结晶层状外延生长，薄膜表面及界面的平整度很好。     

GaSb半导体表面极化子基态能量的研究

采用Ｌ．Ｌ．Ｐ方法导出表面极化子的基态能量,声子平均数,讨论了电子在反冲效应中发射和吸收不同波矢声子之间相互作用对ＧａＳｂ半导体表面中表面极化子基态能量的影响。数值计算结果表明：当动量趋于零时,声子之间的相互作用对极化子性质无影响;当动量达到某一值时,声子之间相互作用的能量占极化子总能量中非常显著的部分;随着动量（平方）的增加,声子平均数近似线性地增加。     

GaSb衬底上分子束外延生长的低温GaSb薄膜的低缺陷表面

本论文系统的研究了,随着GaSb薄膜生长温度的降低,V/III比的变化对薄膜低缺陷表面质量的影响。为了获得良好表面形貌的GaSb外延层,生长温度与V/III比均需要同时降低。当Sb源裂解温度为900℃时,生长得到低缺陷表面的低温GaSb薄膜的最佳生长条件是生长温度为在再构温度的基础上加60℃且V/III比为7.1。     

几种α相Si3N4纳米结构的TEM表征

作为一种陶瓷材料，氮化硅(Si3N4)具有许多优良的性质，如高强度、高硬度和高红外吸收率，耐磨性、耐高温性和耐腐蚀性等。一维尺度的纳米结构是未来纳米器件的基本组成单元。     

分子束外延InAs量子点的RHEED实时原位分析

介绍了利用反射式高能电子衍射(RHEED)方法在自组装InAs量子点制备过程中进行结构分析的理论研究与实验工作的最新进展。从反射式高能电子衍射在InAs量子点临界转变状态测定、量子点表面取向、量子点应力分布测定、量子点形核长大动力学过程研究等方面的应用,可以看出RHEED在InAs量子点形成过程中对多种结构特征的原位分析具有突出优势。反射式高能电子衍射仪作为分子束外延系统中的标准配置,已成为一种对InAs量子点微观结构进行分析的简易而理想的分析测试工具。随着反射式高能电子衍射以及衍射理论的进一步发展,必将促进InAs量子点结构的精确表征水平的提高,进而实现更加理想结构的InAs量子点的制备及其应用。     

尖晶石型LiMn2O4晶体中的相变序列

在研究三维钙钛矿型晶体ABX3，例如La1-xCaxMnO3的过程中，人们清楚地知道它们在温度变化的过程中可能的相变类型。在高温时，他们都是立方晶体。在降温的过程中，La1/3Ca2/3Mn1/3^3 Mn2/3^4 O3晶体中的MnO6氧八面体绕着立方晶体的[011]方向倾转，于是生成了a0=[011]ac，b0=[200]ac，c0     

用电子显微镜研究卤化银微晶体的特殊结构

由于含在碘溴化银微晶体内部的碘能向内吸纳光空穴,从而避免感光材料在曝光时形成的光电子和光空穴的复合作用,这就大大提高了入射光子的利用效率,从宏观上讲,也就可以提高卤化银感光材料的感光度。但按照常规方法制备的碘溴化银微晶体,很难使其碘含量做到很高。因为从理论上讲,碘搀合进溴化银昌格形成混晶的最大含量不超过40%,再加上制备条件的种种限制,最大碘含量还远远低于这个值。我们利用电脑控制的平衡双注仪首先制备出四连双角锥碘化银晶体,如图1所示。看上去,它们是在一个四面体的四个面上各生长出一个双角锥体,每个双角锥体的一个…     

GaSb晶片钝化工艺对抛光表面的影响

锑化镓(GaSb)作为常用的III-V型半导体材料,因其易于氧化的性质而限制了其应用效果,而硫钝化是一种常见而有效的应对手段。该文选取了硫化铵溶液,对化学机械抛光后的晶片表面进行处理,以研究硫钝化工艺中钝化时间对抛光面的影响。实验结果通过原子力显微镜(AFM)和X线光电子能谱(XPS)进行了表征,研究发现,经硫化铵溶液处理后,与Ga相比,Sb的硫化程度更完全,且该程度会随着硫化时间的延长而逐渐加大。另外,处理时间长会加重GaSb晶片表面的腐蚀,使其表面起伏加剧,表面粗糙度增大。     

In situ observation of surface morphology of InP grown on singular and vicinal (001) substrates

Surface morphology of InP layers is monitored during organometallic vapor phase epitaxy using an in situ diffuse laser light scattering technique. Changes in the diffuse scatter signal are noted for several substrate orientations near the (001) plane and at various growth temperatures. The diffuse scatter signal is shown to be a semi-quantitative indicator of surface roughness through post-growth examination of the samples with phase contrast optical microscopy and atomic force microscopy. Singular substrates consistently have almost featureless surfaces and very little diffuse scattering during growth. Vicinal substrates display a more complicated morphological evolution which cannot be deduced from the diffuse scattering alone but which does produce characteristic changes in diffuse scattering.     

Oxide removal from the GaSb surface and fabrication of MBE GaSb photodiodes and Au–GaSb schottky diodes

Oxide removal from GaSb surfaces by several wet chemical treatments and subsequent thermal annealing was investigated. Preferable wet chemical treatments by which surface oxides could be removed effectively at room temperature were evaluated in the experiments. This method can be effectively applied to fabrication processing of MBE GaSb photodoides and Au–GaSb Schottky doides. Low-reverse-leakage GaSb photodiodes and near ideal Au–GaSb Schottky diodes were thus obtianed.     

SnAgCu钎料焊点电化学迁移的原位观察和研究

通过恒定电压条件下的水滴实验,对Sn-4Ag-0.5Cu钎料焊点的电化学迁移(ECM)行为进行了原位观察和研究。结果表明,树枝状的金属沉积物总是在阴极上生成,并向着阳极方向生长,在接触阳极的瞬间,发生短路失效。外加电压不超过2 V时,形成的沉积物数目往往比较少并且粗大。焊点间距的减少和外加电压的增加都会使得ECM造成的短路失效时间显著缩短。当钎料不能完全包裹焊盘或者焊盘局部位置上钎料的厚度很薄时,发生ECM的金属除了来自钎料焊点,还来自Cu焊盘;钎料中的Ag不发生迁移。     

单晶钽裂纹尖端的位错原位观察

本文利用原创双金属片技术,在透射电子显微镜中实现了对小尺寸单晶钽(Ta)拉伸变形的原位实验观察.由于裂纹尖端的塑性区具有与材料整体塑性变形类似的特征,因此本实验针对裂纹尖端处的位错行为进行了研究.实验发现随着裂纹的扩展,有大量呈弯曲或钩状的位错不断形核,并朝着位错弯曲的部分滑移.在进一步的拉伸应力作用下,位错的长直部分不断长大并使这些位错在裂纹尖端堆积.对裂纹尖端的原位高分辨图像观察,发现在单晶钽中有大量伯氏矢量b=1/2〈111〉型位错的形核和逃逸现象.因此,证明这些混合位错对BCC单晶钽的塑性变形有一定贡献,并首次给出了纳米尺度材料中位错堆积的实验证据.     

In situ observation of the growth mechanisms of carbon nanotubes under diverse reaction conditions

We report in situ environmental transmission electron microscope observations of the nucleation and growth of multi-wall and single-wall carbon nanotubes formed by the catalytic decomposition of acetylene (C2H2) on Ni/SiO2 catalyst. The growth rate, structure and morphology of the carbon nanotubes formed depended upon reaction temperature and pressure. Under 20-100 mTorr of gas pressures at 480 degrees C, serpentine-shaped or zigzag, multi-wall carbon nanotubes grew at an average rate of 35-40 nm sec(-1). At pressures <10 mTorr at the same temperature, straight single-wall carbon nanotubes with nearly uniform diameters (approximately 3.5 nm) formed at average growth rates of 6-9 nm sec(-1). The growth of both straight and serpentine carbon nanotubes tends to proceed at non-uniform rates, with frequent pauses followed by growth spurts. The nanotubes frequently contained sharp bends that turned the nanotube axis by approximately 60 degrees and approximately 120 degrees. We conjecture that the bends are related to the change in growth direction that is dictated by the crystallographic orientation of the catalyst particle. The rotations of the nanometer-sized catalyst particle may be caused by transient melting-recrystallization events caused by local thermal variations. The nanotube attempts to follow the preferred growth direction, while simultaneously attempting to maintain a seamless 3-coordinated graphene wall. This latter condition is most easily satisfied by the introduction of pentagon-heptagon defect pairs dissociated to the opposite sides of the nanotube creating the 60 degree bend.     

双相不锈钢冷轧退火组织转变的EBSD原位研究

本文采用扫描电子显微镜（ SEM）及电子背散射衍射（ EBSD）技术对经30％压下量冷轧的双相不锈钢UNS S32304在1050℃下退火的显微组织转变进行了原位追踪。结果表明,轧制变形后,两相的变形抗力具有明显差异,奥氏体塑性变形量较比铁素体大;经1050℃真空退火2 min后,两相晶内取向差的变化表明铁素体较比奥氏体发生了更大程度的回复;再经1050℃真空退火5 min后,样品中两相晶粒取向与其初始取向具有较大差异,表明发生了以再结晶为主并伴有少量相变反应的组织变化。     

In situ FTIR and surface analysis of the reaction of trimethylgallium and ammonia

Using a combination of in situ FTIR spectroscopy and detailed surface analysis, we find that TMGa decomposes at the same rate in either hydrogen or nitrogen forT < 300° C. Although ammonia does not decompose under these conditions, mixing TMGa with ammonia increases the rate of methane formation. Reacting perdeutroammonia with TMGa shows that hydrogen from the ammonia is incorporated into the product methane (whereas deuterium in the gas phase is not incorporated into the gaseous product). TMGa and ND₃ do react; however, nitrogen incorporation in the growing film is temperature dependent. Further, although the decomposition of TMGa occurs in the gas phase, the last steps of the decomposition/reaction occur on the substrate surface.     

In situ amplification of a signal stored upon a dielectric surface

Electrostatic latent image development (ELID) is a method of amplifying storage tube information in which electronic charge patterns stored upon a target may be enhanced by secondary emission upon the incidence of a flood beam. Experimental evidence is given for this effect, using the WX-4384 electrostatic slow scan vidicon and the WX-5074 Optechon storage camera tube, showing measured gains greater than 16 times. There has been demonstrated gain which brought a signal, originally completely obscured by target disturbance, up to a level that is easily discernible. There is a definite increase in signal-to-noise ratio. The analytical expression derived for the gain as a function of electron charge incident on the storage surface during the action and the voltage of the first crossover indicates that large gains may be possible for small stored signals.     

用RHEED方法分析半导体薄膜特性

在讨论ＲＨＥＥＤ原理的基础上，介绍了组建的ＲＨＥＥＤ和其附属的真空系统，并用此装置得到了Ｓｉ薄膜的ＲＨＥＥＤ衍射花样。本文还对实验条件和实验结果进行了简单的分析和介绍。