SiCp/ZL109复合材料中15R SiC/Si界面的TEM研究

用TEM研究了离心铸造的SiCp/ZL109复合材料中15R SiC/Si界面。SiC/Si界面结合紧密，无孔洞，无过渡层。15R SiC与其周围的Si保持以下位向关系：（11^-05)SiC//(1^-11^-)Si,[112^-O]SiC//[1^-12]Si。     

复合材料中β—SiC内部裂纹的TEM研究

材料的断裂，特别是实用结构材料的断裂，人们极为关注，并进行了大量的理论和实验研究，但就其机制来说，至今仍未能得到很好认识，主要原因在于对裂尖的结构及受载条件下的形变行为缺乏深入的了解。近年来，Ｏｈｒ［１］等人利用ＴＥＭ中的原位观察装置，研究了一些金属...     

SiC颗粒增强Al-Si复合材料中的SiC及其界面

以常规TEM为工具,对SiCpZL109复合材料中SiC颗粒及其界面进行了研究,除观察到大量α型六方6HSiC外,还观察到少量α型六方4H和菱形15RSiC。观察到的都是单一的SiCAl及SiC界面,无论是SiCAl或SiCSi界面,界面清洁,结合紧密,无孔洞,无反应过渡层。     

飞秒激光加工SiC/SiC复合材料厚板的孔型特征研究

为了探究飞秒激光加工SiC/SiC复合材料厚板的孔型特征, 采用光束同心圆填充扫描方式对厚度为4mm的SiC/SiC复合材料进行制孔实验, 分析了飞秒激光加工参数对入口直径、孔深、锥度等孔型特征的影响规律和影响机理。结果表明, 脉冲能量、重复频率、线重合度以及扫描速率对小孔入口直径影响较小, 但对孔深和锥度影响较大; 上述实验参数与光束扫描面积内的能量密度密切相关, 小孔锥度随能量密度增大而减小, 小孔深度则反之; 当采用最大脉冲能量130μJ、最大重复频率100kHz、最小扫描速率100mm/s、最大线重合度77%以及最小进给量0.1mm时, 小孔锥度达到最小值12.38°; 上层材料对光束的遮挡以及排屑困难导致深孔加工锥度不易控制。该研究可以为今后SiC/SiC超快激光制孔应用提供参考。     

SiC/Cu-Al复合材料无压浸渍制备工艺的研究

利用化学镀法在SiC颗粒表面包覆Cu层制备了SiC/Cu复合粉体,然后将其压制成预制体并在熔融铝液中无压浸渍,制出了SiC/Cu-Al复合材料.研究了浸渍温度和时间对所制SiC/Cu-Al复合材料浸渍效果的影响.结果表明:SiC颗粒表面的Cu包覆层分布均匀;在800℃、保温2h条件下制备的SiC/Cu-Al复合材料显微...     

ZnO/SiC/Si(111)异质外延

使用SiC作为过渡层,采用自行设计建造的连通式双反应室高温MOCVD系统很好地克服了ZnO和SiC生长时的交叉污染问题,在Si基片上外延出高质量的ZnO薄膜.测量了样品的XRD和摇摆曲线,以及室温下的PL谱.实验结果表明,SiC过渡层的引入大大提高了ZnO薄膜的质量和发光性能,并有望实现在Si上制备ZnO单晶薄膜.     

ZnO/SiC/Si(111)异质外延

使用SiC作为过渡层,采用自行设计建造的连通式双反应室高温MOCVD系统很好地克服了ZnO和SiC生长时的交叉污染问题,在Si基片上外延出高质量的ZnO薄膜.测量了样品的XRD和摇摆曲线,以及室温下的PL谱.实验结果表明,SiC过渡层的引入大大提高了ZnO薄膜的质量和发光性能,并有望实现在Si上制备ZnO单晶薄膜.     

C~+注入Si形成SiC/Si异质结构的椭偏光谱

用椭偏光谱法测量了 ( 35ke V,1 .0× 1 0 18cm- 2 )和 ( 65ke V,1 .0× 1 0 18cm- 2 ) C+ 注入 Si形成的 Si C/Si异质结构 .应用多层介质膜模型和有效介质近似 ,分析了这些样品的 Si C/Si异质结构的各层厚度及主要成份 .研究结果表明 :注 35ke V C+ 的样品在经 1 2 0 0℃、2 h退火后形成的 Si C/Si异质结构 ,其β- Si C埋层上存在一粗糙表面层 ,粗糙表面层主要由β- Si C、非晶 Si和 Si O2 组成 ,而且 β- Si C埋层与体硅界面不同于粗糙表面层与 β- Si C埋层界面 ;注 65ke V C+的样品在经1 2 50℃、1 0 h退火后形成的 Si C/Si异质结构 ,其表层 Si是较     

C+注入Si形成SiC/Si异质结构的椭偏光谱

用椭偏光谱法测量了(35keV,1.0×10118cm-2)和(65keV,1. 0×1018cm-2)C+注入Si形成的SiC/Si异质结构.应用多层介质膜模型和有效介质近似,分析了这些样品的SiC/Si异质结构的各层厚度及主要成份.研究结果表明:注35keV C+的样品在经1200 C、2h退火后形成的SiC/Si异质结构,其β-SiC埋层上存在一粗糙表面层,粗糙表面层主要由β-SiC、非晶Si和SiO2组成,而且β-SiC埋层与体硅界面不同于粗糙表面层与β-SiC埋层界面;注65keV C+的样品在经1250 C、10h退火后形成的SiC/Si异质结构,其表层Si是较完整的单晶Si,埋层B-SiC分成三层微结构,表层Si与β-SiC埋层界面和β-SiC埋层与体硅界面亦不相同.这些结果与X射线光电子谱(XPS)和横截面透射电子显微镜(TEM)的分析结果一致.     

1200V 200A Si/SiC混合模块性能对比研究

提出了一种SiC混合模块,相比传统的Si IGBT模块,将Si续流二极管替换成SiC SBD。两种模块的额定参数均为1 200V/200A,在相同的测试条件下,分别测试其动、静态参数及波形,对比研究测试数据,混合模块中二极管反向恢复损耗可以降低84%,总的开关损耗可以降低40%。提取模块的寄生电感数值为13.3nH,结合动态测试波形,混合模块可以满足正常使用。     

The doped Si/SiO2 interface

A study is reported of the influence of dopant atoms on the SiSiO₂ interface states of thermally oxidized silicon. It was found that acceptor or donor atoms induce interface states and oxide charges. The effect is largest in the case of acceptor dopants and is independent of the doping process. The influence of the dopant atoms on oxide charge is probably related to the different segregation coefficients of acceptors and donors.     

The influence of mobile ions on the Si/SiO2 interface traps

An investigation of the relation between mobile ions and interface traps was carried out, using an appropriate technique to determine the number and type of mobile ions. It was found that mobile ions do not cause interface traps in the middle 0.8 eV of the bandgap. It appears that interface traps are rather caused by some stress effect. The results are considered in light of previously reported work.     

Laser-induced self-organization of nano-wires on SiO2/Si interface

Original observation of new graded band gap structures formed on the surface of elementary Si semiconductor at studying the optical properties of Si nano-hills formed at the SiO₂/Si interface by pulsed Nd:YAG laser irradiation is reported. The self-organized nano-hills on Si surface are characterized by a strong photoluminescence in the visible range of spectrum with a shoulder extended to the long-wave part of the spectrum. The feature is explained by the quantum confinement effect in nano-hills-nano-wires of gradually changing diameter.     

Effect of SiO2/Si interface roughness on gate current

In many theoretical investigations of the electric-tunnel effect through an ultrathin oxide in metal-oxide-semiconductor (MOS) structure, it is commonly assumed that the oxide is of uniform thickness. One example of nonuniformity in oxides is interface roughness. Interface roughness effects on direct tunneling current in ultrathin MOS structures are investigated theoretically in this article. The roughness at SiO₂/Si interface is described in terms of Gauss distribution. It is shown that the transmission coefficient increases with root-mean-square (rms) roughness increasing, and the effect of rms roughness on the direct tunneling current decreases with the applied voltage increasing and increases with rms roughness increasing.     

冷轧SiCw/Al复合材料组织结构TEM研究

SiCw/Al复合材料的研究重点已经转移到应用研究方面。制约其广泛应用的问题是二次加工,该问题的解决是SiCw/Al复合材料迈向广泛应用的关键[1～3]。本文即是针对该复合材料二次加工工艺之一的冷轧变形问题开展的研究。通过冷轧前的预先热挤压变形,实现了SiCw/L3复合材料的大应变冷轧变形,并用透射电子显微镜研究了冷轧组织结构。实验方法试验所用材料采用压力铸造法制备。所用晶须为国产β-SiCw,基体选用工业纯铝,晶须体积分数为15%。显微组织观察用PILIPSCM12透射电子显微镜。用机械方法磨试样至40μm,然后在带有低温冷却台的氩离子…     

不同氧化退火工艺下SiO2/SiC界面特性研究

The effect of the different re-oxidation annealing （ROA） processes on the SiO2/SiC interface charac- teristics has been investigated. With different annealing processes, the flat band voltage, effective dielectric charge density and interface trap density are obtained from the capacitance-voltage curves. It is found that the lowest interface trap density is obtained by the wet-oxidation annealing process at 1050 ℃ for 30 min, while a large num- ber of effective dielectric charges are generated. The components at the SiO2/SiC interface are analyzed by X-ray photoelectron spectroscopy （XPS） testing. It is found that the effective dielectric charges are generated due to the existence of the C and H atoms in the wet-oxidation annealing process.     

Determination of Si/SiO2 interface roughness using weaklocalization

The interface roughness of intentionally textured Si/SiO₂ interfaces was measured using the quantum weak localization (WL) correction to the electrical conductivity at low temperatures. The deduced roughness was confirmed by observation of the Si surface replicas by atomic force microscopy (AFM). Quantitative agreement between the two methods was found (Δ=1.2 to 1.4 Å from WL and 1.35 Å from AFM). For a surface with artificially induced texture, it is found that WL can easily distinguish a significant increase in roughness relative to the smooth surfaces. AFM confirms this qualitative conclusion     

The structure of Si nanocrystals on SiC

Si nanocrystals grown on cubic SiC have been characterized using high-resolution transmission electron microscopy. At lower temperatures nanocrystals grow in two different orientations, whereas at higher temperatures they grow in a single preferred orientation. The nanocrystals are shown to be unstrained; in some cases possibly due to the presence of a thin amorphous wetting layer.