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Semiconductor microclusters prepared with gas evapolation method in an exited rare gas atomosphere

稀有气体气氛下气体蒸发法制备半导体微团簇

基本信息

批准号：
07454070
负责人：
MAEDA Toshiteru
金额：
$ 4.99万
依托单位：
Ishinomaki Senshu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07454070/
关键词：
small particles Micro-crusters Gas evapolation method Raman scattering Carbon nanotubes Phonon dynamics Luminescence spectroscopy Spacially resolved spectroscopy 半導体

项目摘要

We report here some remarkable features we have found during the study on semiconductor (Germanium) small particles and carbon nanotubes.1. We have found that the structure of Ge small particles prepared with the gas evapolation method is affected by excxited Ar atoms in an atomosphere. Raman spectra of these particles shows the amorphous part in the particle is increased by the excited gas evapolation method.2. We have observed light emission from Ar atoms, Ge atoms/clusters(Ge_2, and Ge ions during the evaporation process of Ge in an Ar-gas atmosphere of a few Torrs. The Ar(I) lines are observed regardless of whether the crucible is empty or filled with Ge. Ar atoms are excited through discharge intiiated by electrons thermionically emitted from the hot W wire heating the crucible and accelerated by the potential applied to the wire. The Ge lines are stronger for lower Ar pressures and for lower Ge vapor density, while the Ge_2 line is stronger for highr Ar pressures. This shows the existence of atomic processes for the energy transformation from Ar to Ge during the gas evapolation.3. Raman scattering spectra of single-walled nanotubes with relative small diameter (typically d = 1.1 nm) show size-dependent multiple splittings of the optical phonon peak corresponding to the E_<2g> mode in graphite. This observation is successfully explained by diameter-dependent dispersions of phonons arising from the cylindrical symmetry of the nanotube.4. Phonon modes in single-walled nanotubes (SWNTs) of carbon are reexamined within the framework of a force constant model. The curvature effect of tubules is discussed by comparing with the results obtained by the zone-folding model. The diameter dependent properties of phonon modes are shown to be useful fo analyzing the size distribution of SWNT in the synthesized samples.

本文报道了我们在半导体（锗）小颗粒和碳纳米管的研究中发现的一些显著特征.我们发现，用气相氧化法制备的Ge小颗粒的结构受气氛中Ar原子的激发影响。这些颗粒的拉曼光谱表明，激发气溶胶化法增加了颗粒中的非晶部分.我们在几个Torr的Ar气气氛中，观察到了Ge蒸发过程中Ar原子、Ge原子/团簇（Ge_2）和Ge离子的发光。无论坩埚是空的还是充满Ge，都能观察到Ar（I）线。Ar原子通过放电被激发，该放电由从加热坩埚的热钨丝发射的电子激发，并由施加到丝的电势加速。Ge线在较低的Ar气压和较低的Ge蒸气密度下较强，Ge_2线在较高的Ar气压下较强。这表明在气体扩散过程中存在着从Ar到Ge的能量转换的原子过程.小直径（d = 1.1 nm）单壁纳米管的拉曼散射光谱表明，石墨中E模对应的光学声子峰随纳米管尺寸的变化出现多重分裂<2g>.这一观察结果是成功地解释了直径依赖的色散的声子所产生的圆柱对称的纳米管。在力常数模型的框架内重新研究了碳单壁纳米管（SWNTs）中的声子模式。通过与带折叠模型的结果进行比较，讨论了微管的曲率效应。声子模的直径依赖特性被证明是有用的分析合成样品中的单壁碳纳米管的尺寸分布。