射频等离子体法在单晶硅衬底上形成的非晶碳膜及其性质

由离子和离子束技术形成的非晶碳膜具有良好的电绝缘性、对红外及可见光透明、硬度大、耐腐蚀等优良性质,可望在半导体器件、激光器件、太阳电池和材料保护等方面得到应用而受到重视。近年来很多作者先后报道了用未经质量分析的低能碳离子束直接沉积、离子束溅射沉积、离子镀、射频辉光放电离化碳氢化合物的等离子体沉积、经质量分析的低能碳离子束沉积等方法在单晶硅、玻璃、不锈钢等不同衬底上形成非晶碳膜的结果。碳膜的物理性质与沉积条件有密切关系,根据物理性质非晶碳膜大致可以分为三类,即导电、不透明的类石墨膜;绝缘、透明、质软的类聚合物膜;透明、绝缘、硬度大的类金刚石膜。     

In-situ XAFS study on structures and devitrifications of Ni–B nano-amorphous alloys

The local structures and the devitrifications of Ni₇₀B₃₀ nano-amorphous alloys prepared by chemical reduction method were studied by in-situ X-ray absorption fine structure (XAFS). The results indicate that the preparation temperature strongly affects the local structures of Ni₇₀B₃₀ amorphous alloys. The coordination geometry surrounding Ni atoms is a structure of amorphous Ni-like for the Ni₇₀B₃₀ (273 K) while the Ni₇₀B₃₀ (313 K) has amorphous Ni₃B-like structure. In-situ XAFS analysis revealed that the Ni₇₀B₃₀ amorphous alloy prepared at the low temperature of 273 K is directly crystallized into the metallic Ni in a wide temperature range from 498 to 598 K. However, the crystallization of the sample prepared at the high temperature of 313 K is accomplished in two steps: the generation of intermediate product of crystalline Ni₃B starting from 548 K and finishing at about 573 K; the unique formation of crystalline Ni at about 598 K.     

Relaxation processes in crystalline polymers: experimental behaviour — a review

A comprehensive review of relaxation processes in semi-crystalline polymers is presented. Methods for assignment of phase origin of relaxations are discussed. Experimental results for a variety of polymers ranging from inherently difficulty crystallizable to easily crystallizable are reviewed with emphasis placed on phase origin, phase properties and the effects of the interactions between the crystal and amorphous phases.     

Light-induced defects in hydrogenated amorphous silicon germanium alloys

A selected survey of the phenomenon of light-induced deep defect creation in the hydrogenated amorphous silicon–germanium is presented. First a general review of the early studies that established the key salient features of light-induced degradation in a-Si,Ge:H is given. This is followed by a discussion of a couple of complicating issues that have more recently come to light; namely, the possibility that charged defects play a more central role in the alloys, and that both Si and Ge metastable dangling bonds may be playing a significant role in the alloys with germanium fractions below 20 at%. Following this, the results of some recent studies are summarized that have been focusing on the details of degradation in the low Ge fraction alloys to gain insight into the fundamentals of degradation of amorphous silicon materials in general. This review concludes with an overall assessment of the level of our understanding of degradation in the a-Si,Ge:H alloys and where some key issues are still remaining to be resolved.     

Investigation of intrinsic crystalline Si(111) and amorphous silicon surfaces in air with STM

Crystalline (111) and amorphous silicon surfaces have been studied by scanning tunnelling microscopy. An orientated, reproducible, corrugated structure has been observed on Si(111) surfaces. The voltage dependence of the corrugation amplitude may be attributable to surface states. The surfaces of amorphous silicon thin films show some reproducible structure in the range of a few tens of ångströms, observable only when the applied voltage between the tip and sample is between ?1·3 and +0·4V.     

对带状光纤中心管式缆实测结果的讨论

报道了对带状光纤中心管式缆内各条光纤带、各单根光纤长度和应变实测结果的差异，并对这些实测结果从理论上进行了解释。     

Studying early time HWCVD growth of a-Si:H by real time spectroscopic ellipsometry

We have applied real time spectroscopic ellipsometry and secondary ion mass spectrometry to study the growth of amorphous silicon by hot-wire chemical vapor deposition. Differences in temperature and hydrogen content affect the optical properties of the film. These effects provide valuable insight into the growth process. We have compared a-Si:H films grown at two different temperatures to better understand these effects. Our studies reveal the presence of a distinct 100–200-thick layer at the top of the growing film. The properties of this layer are primarily determined by the ambient conditions in the growth chamber and appear relatively independent of substrate temperature. In contrast, the properties of the bulk of the film are strongly influenced by substrate temperature. These results imply that differences in film properties associated with substrate temperature are the result of subsurface reconstruction and diffusion processes.     

Effect of initiator structure on physical and thermal properties of nylon-6

Nylon-6 is synthesised from ε-caprolactam by an anionic polymerisation method, through a two-step process using sodium metal as a catalyst and diisocyanate-caprolactam block initiator. Two different aliphatic diisocyanates are used. The effects of diisocyanate structure and concentration on percentage cryslallinity, molecular weight, density and thermal properties of nylon are discussed.     

CATALYTIC EFFECT OF FORMIC ACID UPON AMORPHOUS CHROMIUM ELECTRODEPOSITION

ＣＡＴＡＬＹＴＩＣＥＦＦＥＣＴＯＦＦＯＲＭＩＣＡＣＩＤＵＰＯＮＡＭＯＲＰＨＯＵＳＣＨＲＯＭＩＵＭＥＬＥＣＴＲＯＤＥＰＯＳＩＴＩＯＮＷａｎｇＸｉａｎｙｏｕ；ＪｉａｎｇＨａｎｙｉｎｇ；ＧｕｏＢｉｎｇｋｕｎ（ＩｎｓｔｉｔｕｔｅｏｆＭｅｔａｌｌｕｒｇｉｃａｌ...     

电子束诱导非晶GaAs晶化的形核与长大

利用高分辨电子显微镜对电子束辐射诱发非晶GaAs晶化过程现象进行了原位观察。结果表明，具有几个原子大小的原子簇在辐射初期产生，并作为晶化的核心在随后的辐射过程中不断长大；大部分结晶晶粒保持相同的晶体取向，其余少量不同取向的晶粒也与前者保持孪晶关系。电子束辐照诱发非晶GaAs晶化的速率与电子束流密度有关；电子束辐照非晶GaAs结晶不是电子束诱发材料温度升高的结果，而与电子能量有关。本文对辐照晶化的机制和结晶过程进行了讨论。