化合物半导体异质外延层中的缺陷

本文报道了用MBE方法在Si(100)上生成GaAs和用MOCVD方法在GaAs(100)上生成CdTe的异质外延层中的某些缺陷。用JEM-4000EX和JEM-200CX电镜观察,电子束沿晶体的[011]方向入射,观察到的晶体缺陷运用高分辨像和选区衍射技术进行研究和分析。结果表明CdTe/GaAs中主要缺陷是失配位错及微孪晶,而在GaAs/Si中还含有反相无序。     

砷化镓半导体表面自然氧化层的X射线光电子能谱分析

用X射线光电子能谱(XPS)，测量了Ga3d和As3d光电子峰的结合能值，指认了砷化镓(GaAs)晶片表面的氧化物组成，计算了表面氧化层的厚度，定量分析了表面的化学组成；比较了几种不同的砷化镓晶片表面的差异。结果表明：砷化镓表面的自然氧化层主要由Ga2O3、As2O5、As2O3和单质As组成，表面镓砷比明显偏离理想的化学计量比，而且，氧化层的厚度随镓砷比的增大而增加；溶液处理后，砷化镓表面得到了改善。讨论了可能的机理。     

半绝缘砷化镓单晶中AB微缺陷的定量测量方法

报道了非掺杂半绝缘砷化镓单晶中ＡＢ微缺陷显微特征的研究结果,提出了一种自动定量测量微缺陷的方法,并在ＷＤ－５图象处理分析系统中实现了该算法。     

半导体共轭聚合物光学探针的设计及在自发光成像和光声成像中的应用

光学成像因其无侵袭性、高时空分辨率和高灵敏度在生物医学领域得到迅速发展.光学成像中自发光成像包括化学发光成像和长余辉成像不需实时光激发,避免了自发荧光的影响,可以得到较高的灵敏度和信噪比.光声成像则是将光信号通过热膨胀转化为声信号,避免了光散射的影响,具有较高的组织穿透深度.本文针对半导体共轭聚合物光学探针在自发光成像...     

电子功能外延薄膜的电沉积

电沉积作为一种在温和条件下从溶液中合成材料的技术已被广泛应用于在导体和半导体基底表面合成各种功能材料。电沉积一般由人为施加于基底的电刺激（如：施加电位/电流）来触发。这种电刺激通过氧化或还原靠近基底表面的溶液层内部的离子、 分子或配合物从而使该溶液层偏离其热力学平衡状态,随后引起目标产物在基底表面的沉积。在电沉积过程中, 许多实验参数都可能从不同的方面对沉积物的物化性质造成影响。迄今为止,已通过电沉积制备出多种单质（包括金属和非金属单质）、 化合物（例如：金属氧化物、金属氢氧化物、 金属硫化物等）以及复合材料。电沉积制备的这些材料大多为多晶、 织构或外延薄膜的形式。其中, 外延薄膜是一种具有特定的面外和面内晶体生长取向且其晶体取向受基底控制的类单晶薄膜。由于外延薄膜中高度有序的原子排列,它们常呈现出独特的电磁性质。本文总结了常见的电沉积合成路线及影响沉积物外延生长的关键实验因素。此外, 本文简要介绍了用于表征外延薄膜的技术。最后, 本文还讨论了一些采用电沉积制备的具有特殊电子、 电磁及光电特性的功能外延薄膜。     

半导体催化过程的电子机理

近几年来,许多实验事实都揭示了固态物质的催化活性和这类物质所共有的某些特殊的电学性能——半导体性能之间存在着一定的内在联系,因此导致对半导体催化过程在理论上和实验上的深入的研究。现在,国外许多学者对这一领域的研究都给予了极大的重视。在苏联,罗金斯基(Рогинский)及其学派进行了大量研究工作,沃尔肯什坦(Волъкенцтеин)在半导体催化过程的理论解释上亦作了深入的探讨,在这一领域中从事研究的西方科学家还有豪非(Hauffe)、施瓦勃(Schwab)、巴拉万诺(Parravano)等等。     

电化学原子层外延法制备碲化铋薄膜

电化学原子层外延法制备碲化铋薄膜;电化学原子层外延;欠电位;碲化铋;热电薄膜     

表面氧化外延制备钇系涂层导体隔离层

采用表面氧化外延(SOE)方法, 在金属基底上研制NiO隔离层. 通过研究温度、时间等工艺参数对形成立方织构NiO的影响, 摸索出一套可获得单一、尖锐的立方织构NiO, 重复性好, 适合于长带发展的工艺技术. 同时研究了金属基带的表面状态、织构取向对NiO(100)表面的影响. X射线极图观测可直观地看到单一的立方织构, φ扫描检测其半高宽(FWHM)均为7.5°. 扫描电镜观察NiO(100)膜层表面形貌, 无裂纹且较为致密.     

单手性半导体碳纳米管在生物成像中的研究进展

半导体碳纳米管在生物成像、光热疗法和运载药物等生物医学应用中都展现出明显的优势.特别是生物成像,半导体碳纳米管在近红外生物窗口(0.7～1.4 μm)中显示出固有的荧光和强大的光学吸收.半导体碳纳米管不仅可以在体内深层成像中对细胞进行荧光标记,还可以追踪和治疗肿瘤细胞.半导体碳纳米管的电子能带结构和光、电性能均取决于它...     

Step Morphology of Liquid Phase Epitaxial GaAs Determined by Atomic Force Microscopy

Single, double and triple growth spirals were observed on liquid phase epitaxy(LPE) grown layers using atomic force microscopy (AFM). Spiral growth arises from the motion of growth steps in a spiral fashion. The LPE grown GaAs Layers show quite a different step morphology as compared with cleaved GaAs crystals. The step treads are atomically flat planes in the cleaved crystals. but are generally not atomically flat planes and rather bow upwards in the LPE layers. The mechanism arousing this difference is unclear.     

Atomic Force Microscopy Analysis of Statistical Roughness of GaAs Surfaces Originated by Thermal Oxidation

We have determined the important statistical quantities of the rough boundary between a GaAs single crystal and its oxide film formed by thermal oxidation. Thermal oxidation of the GaAs surfaces was performed at the temperature of 500°C. Using mathematical procedures developed for treating AFM data consisting of a family of the values of the heights of the irregularities of this roughness the values of the important statistical quantities of roughness were determined for 11 samples of the GaAs surfaces created by dissolution of the thermal oxide films originated during thermal oxidation of the smooth GaAs samples (the times of oxidation of these 11 samples were within interval of 20min–8 hours). From the AFM analysis of the roughness of GaAs surfaces it was found that the roughnening of these surfaces was the most pronounced for shorter oxidation times, i.e. for times smaller than about 2 hours.     

GaAs(100)解理面的能带弯曲

在真空中解理后,用XPS测得了GaAs样品（110）断面能带弯曲的动态过程．两组重掺杂n型和p型GaAs样品的费米能级分别向禁带中间的方向移动了0.4eV和0．3eV.实验测得重掺杂n型和p型GaAs样品费米能级之差为1．3eV,它们的禁带宽度理论值为1．42eV,这说明结果是合理的．根据实验结果,对引起GaAs表面能带弯曲的可能原因进行了分析讨论．排除了本征表面态、真空中残留气体和X射线辐射等原因,认为解理过程在表面产生的缺陷和解理后表面晶格弛豫过程中产生的缺陷可能是导致能带弯曲的主要原因．     

Composition Modulation in Low Temperature Growth of InGaAs/GaAs System: Influence on Plastic Relaxation

This work focuses on the characteristics of composition modulation in InGaAs/GaAs layers grown by ALMBE at 200°C, and its influence on the degree of plastic relaxation that these layers achieve. The asymmetry in the composition modulation for both directions lying in the (001) growth plane observed by Transmission Electron Microscopy is proposed to explain the asymmetry enhancement in misfit dislocations density, as has been found in these structures. Internal stresses in the material associated with this phase separation could be responsible for the hardening of these low temperature grown InGaAs layers.     

High resolution FTIR measurements of LVM-structure in GaAs

High resolution measurements of LVMs (localised vibrational modes) can give vital information about the configuration of defects within a crystal lattice. Illustrations of this technique for the centres B_As, B(1) and Si_Ga-Ge_As in GaAs are presented.     

GaAs(100)表面氧化的XPS研究

X-ray photoelectron spectroscopy（XPS）was used to study two different oxidation treatments on the GaAs（100）surface———the thermal oxidation in the air,and the ultraviolet-light oxidation in the UV-ozone. A series of properties including the oxide composition,chemical states,the surface Ga/As atomic ratio and the thickness of the oxide layer grown on GaAs surface were compared. The results indicate that the oxide composition,the surface Ga / As atomic ratio and the thickness of the oxide layer oxide on GaAs surface are different for different oxidation methods. The oxides on GaAs surface grown by thermal oxidation in the air are composed of Ga2O3,As2O5,As2O3 and elemental As;and the Ga/As atomic ratio is drifted off the stoichiometry far away. The Ga/As atomic ratio of oxide layer on GaAs surface is increases with the thickness of oxide. However,the oxides on GaAs surface grown by UV-ozone are made up of only Ga2O3 and As2O3,As2O5 and elemental As are not detected,the Ga/As atomic ratio is close to unity. The thickness of oxide layer on GaAs can be controlled by the UV exposing time. The mechanism of oxidation of GaAs is also discussed. The UV-light radiation not only causes the oxygen molecular excited forming atomic oxygen,but also induces the valence electrons of the GaAs excited from the valence band,and then the reactivity of Ga and As atom increase,and they can easily react with the excited atomic oxygen at the same reactive velocity.     

用规整膜板对砷化镓的三维微结构图形加工刻蚀

以微齿轮图形结构作为规整模板 ,用约束刻蚀剂层技术对GaAs样品表面进行了加工刻蚀 .在有捕捉剂H3AsO3存在的情况下 ,规则微齿轮图形能够很好地在样品表面复制 .刻蚀结果与没有捕捉剂存在时的刻蚀结果做了比较 .另外还测试了不同方法制得膜板的性能 ,初步探讨了电化学模板的制作工艺 .     

Ab initio molecular orbital theory study of GaAs clusters: The geometry

We have studied the structure and geometry of neutral and charged atomic clusters consisting of Ga and As atoms via ab initio Hartree–Fock (HF) and second‐order Møller–Plesset methods. The Ga_mAs_n cluster with m≠n composition prefers a nontetrahedral geometry in the charge neutral (q=0) state. These clusters tend to be stable in tetrahedral geometry when appropriately charged. The Ga_mAs_n cluster with m=n composition (1:1 ratio of Ga to As atoms) tends to be stable in a tetrahedral geometry in the charge neutral (q=0) state. With increasing size of the cluster, the geometry of Ga_nAs_n cluster approaches the zinc‐belende‐type crystalline structure. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 563–573, 2000