南海北部白云深水区之基础地质

白云深水区具有复杂而特殊的地质条件：位于中生代俯冲带的构造软弱带、新

Properties of cubic GaN grown by MBE

We review our investigation of cubic GaN films on (001) GaAs, focusing on the structural, optical, and electrical properties of these films. Cubic GaN films grown epitaxially on GaAs suffer from the large lattice mismatch between these two materials in that they contain extremely high densities of structural defects. Surprisingly, the optical quality of these films does not seem much affected by the presence of defects, as intense photoluminescence is detected a? room temperature and above. Finally, the rather high background electron concentrations in our films is shown to be a consequence of contamination with O and not to be an intrinsic property of cubic phase GaN. (C) 1997 Elsevier Science S.A.

一种基于高维形象几何理论的彩色图像增强算法

基于近年来发展起来的全新理论——高维形象几何与仿生信息学，提出一种彩色图像增强算法。本算法将彩色图像看作是高维空间的点，通过对多幅图片的分析，推导出点与点之间的内在联系，提出“模糊-再模糊-清晰”的增强算法，并由实验证明该算法对模糊图像的清晰化有很好的效果。

Zn-doped InGaAs Base Heterojunction Bipolar Transistors Grown by Low Pressure Metal Organic Chemical Vapor Deposition

High performance InP/InGaAs heterojunction bipolar transistors(HBTs) have been widely used in high-speed electronic devices and optoelectronic integrated circuits. InP-based HBTs were fabricated by low pressure metal organic chemical vapor deposition(MOCVD) and wet chemical etching. The sub-collector and collector were grown at 655 ℃ and other layers at 550 ℃. To suppress the Zn out-diffusion in HBT, base layer was grown with a 16-minute growth interruption. Fabricated HBTs with emitter size of 2.5×20 μm~2 showed current gain of 70~90, breakdown voltage(BV_(CE0))>2 V, cut-off frequency(f_T) of 60 GHz and the maximum relaxation frequency(f_(MAX)) of 70 GHz.

我国半导体科学领域基础研究迈入新阶段--国家自然科学基金半导体学科2004年申请概况分析

2004年国家自然科学基金委员会半导体学科受理的面上项目申请数终于有了突破,文中介绍了2004年半导体学科基金申请与资助概况,分析半导体学科受理申请的近期动态,介绍学科拟采取的对策,并附2004年半导体学科批准资助的面上项目及重点项目,供广大科研人员参考.

Ge_xSi_(1-x)材料生长的改善

利用超高真空化学气相淀积(UHV/CVD)系统在650℃生长出表面光亮的GeSi单晶。在1200L/min分子泵与前级机械泵间串接450L/min分子泵，改善了生长环境。串接分子泵后生长的样品的X射线双晶衍射分析表明，外延层衍射峰半宽仅为198arcsec，且出现了Pendellosung干涉条纹，说明外延层结晶质量很好。

Effect of rapid thermal annealing on the Raman spectrum of Si0.33Ge0.67/Si (100) alloy

The effect of thermal annealing on the Raman spectrum of Si0.33Ge0.67 alloy grown on Si (100) by molecular beam epitaxy is investigated in the temperature range of 550-800 degrees C. For annealing below 700 degrees C, interdiffusion at the interface is negligible and the residual strain plays the dominant role in the Raman shift. The strain-shift coefficients for Si-Ge and Ge-Ge phonon modes are determined to be 915 +/- 215 cm(-1) and 732 +/- 117 cm(-1), respectively. For higher temperature annealing, interdiffusion is significant and strongly affects the Raman shift and the spectral shape.

不同干扰条件对辽东山区次生林植物多样性的影响

次生林作为中国森林资源的主体，在其形成和演替过程中，时刻受到自然和人为干扰的影响。明确干扰对次生林，特别是对其植物多样性的影响规律和原因，以及多样性对干扰的响应，对人类利用干扰的正面影响为生产实践服务和保护自然生态系统具有重要意义。本文以辽东山区次生林为研究对象，通过野外调查和数据分析，对不同干扰条件下的次生林植物多样性进行了比较研究，以期为该地区次生林的保护和经营提供参考。 主要结论：1）2004~2005年两个生长季共采集和鉴定植物378种，分别隶属于78科、215属；2）该地区次生林具有较高的物种多样性，各次生林类型Shannon-Weiner多样性指数在3.20~3.60之间；3）依据林分距离居民区和一、二级道路的远近将人为干扰划分为三个水平，即低度干扰、中度干扰和高度干扰，基本呈现了受中等水平干扰的林分具有较高的物种多样性和均匀度，且该地区的人为干扰主要对林分的灌木层和草本层产生影响；4）依据林分郁闭度与受害乔木株数百分比将雪/风灾害干扰划分为三个水平，受各水平雪/风灾害干扰的桦木林在近3年后已基本恢复，多样性水平差异不大，植物多样性随干扰强度的增加呈现平缓的增加趋势；5）该地区人为干扰和自然干扰主要的差异表现在发生方式、发生频度、影响对象、发生面积和空间分布等方面，对林分不同层次物种多样性的影响也有所差异。