分形晶化的Au／a—Ge双层膜的非线性V—I特征

本报道了Ａｕ／ａ－Ｇｅ双层膜的分形晶体现象，并首次测量了Ａｕ／ａ－Ｇｅ双层膜分形晶化的Ｖ－Ｉ特性，实验结果表明：分表晶化后的Ａｕ／ａ－Ｇｅ双层膜具有反常的非线性Ｖ－Ｉ特征，应用隧道结网络（ＲＴＪＮ）模型对实验结果给予了合理的解释。     

退火Ge－Au／Au双层膜中出现的缩聚型分形

利用透射电子显微镜观察了不同温度下退火的Ｇｅ－２２ａｔ．％Ａｕ／Ａｕ双层膜，原态双层膜由Ｇｅ．Ａｕ多晶相和少量Ｇｅ＿（０．４）Ａｕ＿（０．６）亚稳相组成，其中Ａｕ的晶粒很不均匀，没有观察到非晶态Ｇｅ。６０℃至３５０℃退火后均能出现分形图形，但和非晶Ｇｅ晶化形成的多枝叉形貌显著不同。温度升高，分维数增大。认为Ｇｅ－Ａｕ／Ａｕ双层膜中较粗大的Ａｕ晶粒吸收Ａｕ小晶粒引起的缩聚是形成分形的主要原因。     

分形Ge团簇的晶化行为

Ａｕ／ａ－Ｇｅ双层膜中各种图案的形成是一种远离平衡态的非平衡生长现象。近年来，随着非线性科学的发展，这方面工作引起了人们极大的兴趣，具有代表性的工作是侯建国等人［１－４］在各种膜厚比和各种退火温度下的Ａｕ／ａ－Ｇｅ双层膜的分形生长行为。由于非线性系统...     

Au／a—Ge膜退火行为的多重分形研究

研究了Ａｕ／ａ－Ｇｅ双层膜退火后形成花样的分布及其分维。单个分形枝叉的疏密可用简单分维定量描述。多重分形谱可以很好地定量描述了多个分形区的分布的变化，分形花样稀少且分布不均匀的图形对应的分形谱较宽。经１００℃退火６０ｍｉｎ后薄膜中出现分布不均匀的很少的分形花样，经１２０℃退火６０ｍｉｎ后分形花样布满整个薄膜表面，相应的分形谱宽度△α从３．７０减小到０．２３。     

Au/a-Ge膜退火行为的多重分形研究

研究了Ａｕ／ａ－Ｇｅ 双层膜退火后形成分形花样的分布及其分维。单个分形枝叉的疏密可用简单分维定量描述。多重分形谱可以很好地定量描述多个分形区的分布的变化，分形花样稀少且分布不均匀的图形对应的分形谱较宽。经１００℃退火６０ｍ ｉｎ 后薄膜中出现分布不均匀的很少的分形花样，经１２０℃退火６０ｍ ｉｎ 后分形花样布满整个薄膜表面，相应的分形谱宽度Δα从３．７０ 减小到０．２３。     

Si／Ag／Si和Si／Au／Si薄膜分形晶化的TEM和EDS研究

本文利用透射电镜（ＴＥＭ）和Ｘ射线能谱（ＥＤＳ）对ａ－Ｓｉ：Ｈ／Ａｇ／ａ－Ｓｉ：Ｈ和ａ－Ｓｉ：Ｈ／Ａｕ／ａ－Ｓｉ：Ｈ薄膜的分形晶化行为进行了研究。结果表明薄膜的分形晶化强烈依赖于退火条件，分形的形成可用随机逐次触发形核和生长（ＲＳＮＧ）来加以解释。尽管膜内存在明显的互扩散，Ｓｉ分形区厚度与均匀基体区厚度相近。但在ａ－Ｓｉ：Ｈ／Ａｇ／ａ：Ｓｉ：Ｈ膜中存在部分较大的Ａｇ晶粒凸出膜面。     

1—MeV电子辐照对AlxGa1—xAs／GaAs异质面太阳电池性能的影响

对ＡｌｘＧａ１－ｘＡｓ／ＧａＡｓ异抽面太阳电池经１－ＭｅＶ电子辐照前后的性能变化进行实验研究和数值拟合分析，讨论了电池性能衰退的主要原因，并提出了如何提高ＡｌｘＧａ１－ｘＡｓ／ＧａＡｓ异质面太阳电池的抗电子辐照能力的方法。     

分形晶化的Au/a-Ge双层膜的非线性体V-Ⅰ特征

本文报道了Au／a－Ge双层膜的分形晶化现象，并首次测量了An／a－Ge双层膜分形晶化的V－I特性．实验结果表明：分形晶化后的An／a－Ge双层膜具有反常的非线性V－I特征，应用隧道结网络（RTJN）模型对实验结果给予了合理的解释．     

非晶硅基合金多结太阳电池光电特性的模拟计算分析

本文提出了以各子电池的载波子输运方程为基础、用串联等效的方法模拟多结电池的Ｊ－Ｖ特性，并用该方法模拟分析了Ｐ／Ｉ界面态。Ｐ／Ｉ缓冲层带隙梯度对Ｇｌａｓｓ／ＴＣＯ／ａ－Ｓｉ／ａ－Ｓｉ／Ａｌ双结电池光电特性的影响，各子电池本征层为常数带隙的Ｇｌａｓｓ／ＴＣＯ／ａ－Ｓｉ／ａ－ＳｉＧｅ／Ａｌ三结电池的光电特性及其所存在的优势。     

具有热稳定性的Ge／Ni／TiWN／Au与n—GaAs接触性能的研究

采用Ｇｅ／Ｎｉ／ＴｉＷＮ／Ａｕ多层金属化结构与ｎ－ＧａＡｓ的固－固相反应来获得理想的欧姆接触性能。经６００℃热处理或获得７．３×１０＾－＾７Ω．ｃｍ的最小接触电阻率，俄歇能谱分析表明ＴｉＷＮ与Ａｕ之间，以及它们与ＧａＡｓ界面之间的互扩散较小，具有良好的热稳定性。     

Ge／Au和Ge／Ag双层膜中非晶Ge加热晶化的动态观测

本文在JEM—1000高压电镜中对Ge/Au和Ge/Ag双层膜进行了加热动态观测,并与真空退火的结果进行了比较。结果表明,双层膜中非晶Ge的晶化不仅取决于加热温度,而且取决于加热时间。加热条件的不同引起不同的晶化机制。本文讨论了非晶Ge晶化时等轴状缩聚区的形成与长大,并提出了这类区域内的能量平衡条件。     

The role of germanium in evaporated AuGe ohmic contacts to GaAs

Auger depth profiling, electron probe microanalysis, electron beam induced current and conventional scanning electron microscopy have been used to study the inhomogeneous reaction which takes place during the alloying of evaporated AuGe films on (100), n-type GaAs. These measurements have been correlated with I–V and C–V data taken for heat treatment below the AuGe eutectic temperature (360°C) and specific contact resistance measurements above 360°C.The picture which emerges is that of the key role of the germanium in the metallurgical reaction, in addition to its accepted role as the n⁺ dopant. A simple metallurgical model is proposed which is based on the AuGe being the main reactive system at the interface responsible for the formation of the rectangular particles which are the pathways for the current. Minimum contact resistance correlates with the maximum growth of these particles.     

The Role of Au in the Thermoelectric Properties of Amorphous Ge/Au and Si/Au Thin Films

Amorphous Si-Ge-Au thin films exhibit high thermoelectric power. To understand the role of Au in the thermoelectric properties, we studied the structural and thermoelectric properties of Si/Au and Ge/Au thin films. Samples were prepared by electron beam evaporation. Au was found to have two important roles. One is as a carrier source. Therefore, Au composition influences thermoelectric properties. The other role is that Au causes the crystallization of Si and Ge at lower temperature. The grain size ranged from ten to a few tens of nanometers. We conclude that the fine structure is important for high thermoelectric performance.     

The characteristics of AuGe-based ohmic contacts to n-GaAs including the effects of aging

We have investigated and compared the characteristics of Au:Ge, Ni/Au:Ge and Au/Ni/Au:Ge ohmic contact metallizations to ion-implanted and epitaxial n-GaAs layers on semi-insulting substrates. Auger depth profiles of ohmic contacts and SEM of surface microstructures have provided significant insight as to the nature and degradation mechanism of ohmic contacts with aging. An electrolytic tank model with distributed resistors representing nodular or cluster form contacts has been successfully used to understand the effects of non-uniform ohmic contacts. A small degree of change in the semiconductor sheet resistance in the gaps between contacts, with aging at an elevated temperature, has been attributed to possible lateral surface diffusion of Au in the Au:Ge contacts and Ge in the Ni/Au:Ge and Au/Ni/Au:Ge contacts.     

基于混沌、分形理论的多径衰落分析

本文首次将混沌、分形等非线性理论引入多径衰落的研究,针对现场实测数据分析了它的非线性动力特征.首先通过重构状态空间和关联维数验证了其动力机制的有限维自由度,然后通过计算其Lyapunov指数考察了系统的时空演化特性,最后利用分形机制对多径信号进行了重构.研究结果表明,与传统的随机模型相比,非线性动力模型能更恰当地描述多径衰落的内在物理机制.     

Low-temperature Au-induced crystallization of hydrogenated amorphous Si0.5Ge0.5 thin films using Au solution

Low-temperature (∼400 °C) metal-induced crystallization of hydrogenated amorphous Si_0.5Ge_0.5 thin films using Au solution has been investigated by X-ray diffraction, Raman spectra, scanning electron microscopy and atomic force microscopy. It was shown that Au solution significantly promotes the crystallization of the films at low temperatures. The effects of annealing temperature and concentration of the Au solution on the structure and morphology of the films were analyzed. The increase in crystallinity was observed with increasing the annealing temperature. The Raman shifts of Ge–Ge and Si–Ge peaks with the annealing temperature were also discussed.     

基于分形特征的红外图像识别方法

文中首先对红外图像进行预处理,然后根据分形理论提取了红外图像的９种分形特征,用神经网络进行目标识别。这９种分形特征包括基于分形维数的特征,基于Ｈｕｒｓｔ指数的分形特征和基于缝隙的分形特征。最后进行了计算机仿真实验,实验表明基于分形特征红外图像识别方法是可行的,并取得了较好的结果。     

功能电子陶瓷的MOCVD薄膜技术

与常用电子陶瓷薄膜技术相比,ＭＯＣＶＤ技术具有薄膜化学成分、结晶结构和氧化程度易控制,沉积温度低,沉积速率高,薄膜的致密性、均匀性和台阶覆盖性好,可理想生长多组元和多层结构的功能金属氧化物薄膜,能直接由实验室转入规模生产及与硅的大规模集成工艺兼容等优点。应用自制设备及ＭＯＣＶＤ技术,分别在高掺杂硅片和有透明导电膜玻璃的基片上生长了ＴｉＯ２薄膜。测得的１ｍｍＡｕ圆点／ＴｉＯ２薄膜／ｐ＋－Ｓｉ衬底样品的Ｉ－Ｖ和Ｃ－Ｖ特性,清楚地给出了ＭＩＳ结构的行为。淀积在透明导电膜玻璃上的ＴｉＯ２薄膜有电致变色现象。     

Electron-Induced Secondary Electron Emission Properties of MgO/Au Composite Thin Film Prepared by Magnetron Sputtering

As a type of electron-induced secondary electron emitter, MgO/Au composite thin film was prepared by reactive magnetron sputtering of individual Mg target and Au target, and the effects of key process parameters on its surface morphology and secondary electron emission (SEE) properties were investigated. It is found that to deposit a NiO buffer layer on the substrate is conducive to the subsequent growth of MgO grains owing to the lattice matching. The gold addition can raise the electrical conductivity of MgO film and further suppress the surface charging. However, the gold deposition would interfere with the MgO crystallization and increase the surface roughness of MgO/Au film. Therefore, MgO/Au composite thin film with a NiO buffer layer and proper deposition times of MgO and Au can achieve superior SEE properties due to good MgO crystallization, low surface roughness and reasonable electrical conductivity. The optimized MgO/Au composite thin film has a higher SEE coefficient and a lower 1-h SEE degradation rate under electron beam bombardment in comparison with MgO film.     

多孔硅薄膜微结构的分形特性

用扫描电镜(SEM)对厚度不同的多孔硅膜的微结构进行了研究。对于23μm厚的多孔硅膜,其横截面微结构好似海底生长的海藻;而对于6μm厚的多孔硅膜,其表面微结构则像龟壳上的裂纹。通过对在不同放大倍数情况下拍摄的多孔硅的SEM图片进行分析,结果表明多孔硅薄膜的这两种微结构都具有分形特征,而且其分形维数为2.3～2.6。利用扩散限制凝聚模型(diffusion limited aggregation)对这两种微结构的形成过程进行了模拟。