离子辐照后4H-SiC晶体退火前后的光谱研究

分析了高能Pb27+辐照预注入12C+的和未预注入12C+ 4H-SiC样品在,退火前后傅立叶变换红外光谱和拉曼散射光谱的变化。从傅立叶变换红外光谱可以知道,900℃以上的退火使损伤层发生显著恢复;在拉曼散射光谱中可以看到1200℃退火后有石墨相的存在。实验结果说明,高温退火有利于损伤的恢复,使注入到碳化硅中的碳原子发生聚集并引起相变。

铅离子辐照注碳4H-SiC的红外光谱特性研究

主要研究了铅离子辐照注碳4H-SiC样品在3个不同退火温度下傅立叶变换红外光谱的变化。从红外谱的变化可以知道铅辐照注碳4H-SiC样品在一定深度内出现了非晶层,波数在960—1 450 cm-1范围内出现了干涉带,干涉带强度随着退火温度的升高而变弱。1 373 K退火后样品的卢瑟福背散射分析结果显示,一定深度内硅原子的背散射产额明显减少。

120keV的N~+注入SiC薄膜的光谱特性研究

文中主要研究了 12 0keV的N+ 注入后SiC薄膜样品的光致发光谱 (PL)和傅立叶红外光谱(FTIR)特性 .从红外光谱可以看到有明显得碳氮单键、双键、三键等新结构生成 .从PL光谱则发现 36 5nm处的发光峰明显增强 ,这表明N+ 注入使得带隙中深的能级辐射中心复合的效率大幅度提高

Electrochemical fabrication of single-crystalline and polycrystalline Au nanowires: the influence of deposition parameters

We report the electrochemical growth of gold nanowires with controlled dimensions and crystallinity. By systematically varying the deposition conditions, both polycrystalline and single-crystalline wires with diameters between 20 and 100 nm are successfully synthesized in etched ion-track membranes. The nanowires are characterized using scanning electron microscopy, high resolution transmission electron microscopy, scanning tunnelling microscopy and x-ray diffraction. The influence of the deposition parameters, especially those of the electrolyte, on the nanowire structure is investigated. Gold sulfite electrolytes lead to polycrystalline structure at the temperatures and voltages employed. In contrast, gold cyanide solution favours the growth of single crystals at temperatures between 50 and 65 degrees C under both direct current and reverse pulse current deposition conditions. The single-crystalline wires possess a [110] preferred orientation.

Study on nanohardness of helium-implanted 4H-SiC

The hardness of 4H-SiC, which was high-temperature (500 K) helium-Implanted to fluences of 3 x 10(16) Ions cm(-2) and subsequently thermally annealed at the temperature ranging from 773 to 1273 K, was studied by nanoindentation It is found that the hardness of the implanted 4H-SiC increases at the first, then decreases, and then increases again with increasing annealing tempeature in the temperature range of 500-1273 K, and significant increase in hardness is observed at 773 K. The behavior is ascribed to the changes of the density, length, and tangling of the covalent Si-C bond through the recombination of point defects, clustering of He-vacancy, and growth of helium bubbles during the thermal annealing