GaAs和AlGaAs MBE外延生长动力学研究

研究了在ＧａＡｓ（００１）衬底上外延生长ＧａＡｓ、ＡｌＧａＡｓ材料过程中反射高能电子衍射（ＲＨＥＥＤ）的各级条纹及其强度随生长过程的变化。通过对各级条纹强度振荡周期和位相的分析,应用二维成核层状生长模型解释了实验结果：生长表面形貌的周期性变化导致了ＲＨＥＥＤ各级条纹及其强度的周期性变化。     

Si1-xGex/Si多层异质外延结构的研究

对制作的Ｓｉ１－ｘＧｅｘ／Ｓｉ多层异质外延结构进行了研究。并对其做了反射高能电子衍射（ＲＨＥＥＤ）、Ｘ射线衍射（ＸＲＤ）和扩展电阻（ＳＲ）等测量，给出了利用这种结构研制出的异质结双极晶体管（ＨＢＴ）的输出特性曲线。     

CoSi_2超薄外延膜的生长研究

用质量分离的离子束外延（ＭＡＬＥ－ＩＢＥ或简作ＩＢＥ）法在ｎ－Ｓｉ（１１１）上生长了ＣｏＳｉ２超薄外延膜．厚度为１０～２０ｎｍ的ＣｏＳｉ２薄膜的结构特性已由ＡＥＳ、ＲＨＥＥＤ及ＲＢＳ作了研究．实验结果表明Ｃｏ的淀积率对ＣｏＳｉ２单晶生长来说是一个关键因素     

Si_(1-x)Ge_x/Si多层异质外延结构的研究

对制作的 Ｓｉ１－ｘＧｅｘ／Ｓｉ多层异质外延结构进行了研究。并对其做了反射高能电子衍射（ＲＨＥＥＤ）、Ｘ射线衍射（ＸＲＤ）和扩展电阻（ＳＲ）等测量,给出了利用这种结构研制出的异质结双极晶体管（ＨＢＴ）的输出特性曲线。     

德国电动悬挂输送系统及其在我国邮件处理中心的应用可能性分析

介绍了德国ＳＣＨＩＥＲＨＯＬＺ公司生产的ＥＨＢ６２４型电动悬挂输送系统的组成、功能和特点，通过与我国推式悬挂设备实际使用情况的比较，分析了该设备在我国邮政领域应用的可能性。     

MPEG—2和DVD技术研讨

ＭＰＥＧ－２是数字电视广播（ＤＶＢ）、ＨＤＴＶ、ＤＶＤ等的基础，文章首先叙述了ＭＰＥＧ－２的图像压缩编码，然后介绍了ＭＰＥＧ－２的数据结构，对ＭＰＥＧ－１和ＭＰＥＧ－２进行了比较。并对ＤＶＤ标准和ＤＶＤ的技术要点作了全面介绍。     

使用EDFA长距光纤纤维的最新进展

本文介绍了使用ＥＤＦＡ中继器的长距光纤系统的限制因素和设计考察，评述了近期的实验演示，并讨论了使用ＷＤＭ和光孤子的未来系统。     

Si（001）上MBE异质生长Ge中表面活化剂Sd的作用的研究

本利用ＲＨＥＥＤ、Ｘ射线双晶衍射及ＴＥＭ等技术，研究了在Ｓｉ（００１）衬底上，用晶化了的列定形Ｇｅ层做缓冲层ＭＢＥ生长Ｇｅ时，引入表面活化剂Ｓｄ所产生的影响。研究表明，Ｓｄ的引入将全使Ｓｉ（００１）衬底上无定形Ｇｅ膜的晶化温度显提高，并在一定的生长条件下，破坏Ｇｅ外延层的结晶性。     

基于Internet/MIME的EDI技术研究

本文首先介绍了基于Ｉｎｔｅｒｎｅｔ的ＥＤＩ应用背景，在分析Ｉｎｔｅｒｎｅｔ／ＭＩＭ电子邮件标准的基础上，讨论了有关ＥＤＩ单证封装技术，随后，介绍了基于Ｉｎｔｅｒｎｅｔ／ＭＩＭＥ的ＥＤＩ单证安全传输技术，并展望了基于Ｉｎｔｅｒｎｅｔ／ＭＩＭＥ的ＥＤＩ应用前景。     

EDI标准UN／EDIFACT及其应用

本文主要描述了ＥＤＩ标准及其体系结构，对当今国际ＥＤＩ主流标准ＵＮ／ＥＤＩＦＡＣＴ作了重点介绍，并结合具体应用实例介绍了ＥＤＩ报文结构标准。     

A real-time quantitative assessment of self-assembled quantum dots by reflection high-energy electron diffraction

A method for in-situ quantitative characterization of quantum dots during growth is provided using the readily available reflection high-energy electron diffraction (RHEED). RHEED patterns of uncapped self-assembled InAs/GaAs quantum dots are investigated theoretically and experimentally. Previously predicted intensity fringes along chevron tails of quantum dot's RHEED diffraction spots are observed experimentally. Post-growth atomic force microscopic images and theoretical RHEED images of the same are obtained parallel to experimental data. The bounding facets of the quantum dots are determined using the angle between the chevrons. The size (height) of the quantum dots is determined using the periodicity of intensity fringes along the chevrons during growth.     

Some aspects of the RHEED behavior of low-temperature GaAs growth

The reflection high-energy electron diffraction (RHEED) behavior manifested during MBE growth on a GaAs(001) surface under low-temperature (LT) growth conditions is examined in this study. RHEED and its intensity oscillations during LT GaAs growth exhibit some particular behavior. The intensity, phase, and decay of the oscillations depend on the beam equivalent pressure (BEP) ratio and substrate temperature, etc. Here, the intensity dependence of RHEED behavior on the BEP ratio, substrate temperature, and excess of As content in the layer are examined. The change in the decay constant of the RHEED oscillations is also discussed.     

Surface structure of plasma-etched (211)B HgCdTe

The surface of (211)B HgCdTe has been studied by reflection high-energy electron diffraction (RHEED) and atomic force microscopy (AFM). RHEED analysis of the as-grown Hg-rich molecular beam epitaxy (MBE) (211)B HgCdTe suggests the surface reconstructs by additional Hg incorporation. The plasma-etched (211)B HgCdTe surface is crystalline but stepped and facetted. RHEED analysis indicates asymmetric pyramids (base dimensions ≈0.5×1.1 nm) are formed to minimize surface Hg concentration. The AFM examination of plasma-etched (211)B HgCdTe reveals oriented mesoscopic features.     

RHEED振荡精确测量AlGaAs生长速率研究

采用分子束外延技术,在GaAs衬底上生长GaAs,AlAs和AlGaAs时,实现RHEED图像和RHEED强度振荡的实时监测已被证明是一种有效工具。通过RHEED可讨论GaAs表面结构和生长机制,并可以估算衬底温度,更重要的是能计算出材料的生长速率。RHEED强度振荡周期决定生长速率,每一个周期对应一个单层。实验测量GaAs的生长周期为0.82s,每秒沉积1.22单分子层,AlAs的生长周期为2.35s,每秒沉积0.43单分子层。     

Using neural networks to construct models of the molecular beamepitaxy process

This paper presents the systematic characterization of the molecular beam epitaxy (MBE) process to quantitatively model the effects of process conditions on film qualities. A five-layer, undoped AlGaAs and InGaAs single quantum well structure grown on a GaAs substrate is designed and fabricated. Six input factors (time and temperature for oxide removal, substrate temperatures for AlGaAs and InGaAs layer growth, beam equivalent pressure of the As source and quantum well interrupt time) are examined by means of a fractional factorial experiment. Defect density, X-ray diffraction, and photoluminescence are characterized by a static response model developed by training back-propagation neural networks. In addition, two novel approaches for characterized reflection high-energy electron diffraction (RHEED) signals used in the real-time monitoring of MBE are developed. In the first technique, principal component analysis is used to reduce the dimensionality of the RHEED data set, and the reduced RHEED data set is used to train neural nets to model the process responses. A second technique uses neural nets to model RHEED intensity signals as time series, and matches specific RHEED patterns to ambient process conditions. In each case, the neural process models exhibit good agreement with experimental results     

外延GaN基薄膜表面应变演变RHEED分析

介绍了反射式高能电子衍射仪(RHEED)衍射原理以及半导体薄膜表面原子间距与其衍射图像间距成反比例关系。分析了采用ECR-PEMOCVD生长技术,在α-Al2O3衬底上低温外延GaN基薄膜(氮化层、缓冲层、外延层)工艺过程。通过对RHEED图像分析软件获取不同工艺过程中的外延薄膜衍射条纹间距的数据分析、计算、比较,得到薄膜表面衍射图像间距的大小,依据RHEED衍射图像与原子面间距之间的对应关系,分析薄膜表面的应变状态演变情况。分析计算结果表明生长20min氮化层、20min缓冲层的表面原子层处于压应变状态,而生长180min的AlN外延层,表面则处于完全弛豫状态。     

RHEED studies on Z-cut LiNbO3

Improved and indexed RHEED patterns are reported for the (001) plane of lithium niobate, together with the procedure necessary for correcting the RHEED patterns for refraction effects. A mean inner potential in the crystal of 15 ± 3eV is consistent with our observations.     

[(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。     

RHEED在计算Al2O3晶面间距中的应用

反射式高能电子衍射仪(RHEED)是一种表面分析工具,以往都是用来对晶体进行定性观察,以研究晶体的结晶状况,很少用来进行晶体结构的定量计算.在分析RHEED的工作原理的基础上,研究了A1203衍射条纹宽度、电子束入射方向和晶面方向之间的关系,并尝试利用RHEED来分析和计算Al2O3(0001)面上两个重要方向上的晶面间距,得到了理想的结果.由于RHEED是一种原位监测仪器,所以可对薄膜的生长进行实时原位监测.在测晶面间距等常数时,与对样品要求极高的透射电子显微镜相比,RHEED更方便.     

RHEED优化MBE生长中波MCT薄膜工艺

在分子束外延(MBE)中波HgCdTe薄膜过程中,利用反射式高能电子衍射(RHEED)对衬底表面脱氧和生长过程中生长参数对材料特性的影响进行研究.通过观察RHEED图样的变化,确定了衬底的脱氧状况,获得了生长中衬底温度等生长参数变化引起材料结晶的变化规律,为MBE生长HgCdTe薄膜实验的可控生长提供有效帮助;生长结束后,通过SEM、Hall等手段对HgCdTe的表面缺陷、电学参数等性能进行了初步研究,证明实验说成长的材料基本满足器件制备的要求.