摘要
通过局部加热系统中的化学气相沉积法(chemical vapor deposition,CVD)实现了碳纳米管(carbo nnanotube,CNT)和金刚石晶体的选择性生长.加热系统只加热硅衬底而对反应过程及担载气体没有加热作用.在衬底温度为700℃时,没有生成CNT或明显的金刚石颗粒.当温度升到740℃时,仍没有CNT生成,但是在模样化的铁膜上生成许多尺寸为几十纳米的金刚石颗粒.温度为770℃时,在铁膜的中央部位生成许多尺寸为几十到几百纳米的金刚石颗粒,而在铁膜的边缘部位可同时观测到一些CNT的生成.当温度达到850℃时,CNT的生长区域扩大而纳米金刚石的平均尺寸和生成密度减小.在910℃的高温下,生成了大量的CNT,其平均直径为20nm,和通常的热CVD法生成的CNT相同.在较低的衬底温度下,表面催化反应占主导地位而可能诱导具有sp3结构的纳米金刚石的生成.随着衬底温度的增加,围绕在衬底周围的气体被加热,在达到其气相自聚合温度后形成不饱和碳氢链,这些生成的碳氢链在sp2结构CNT的生成中起到了重要的作用.
Selective growth of carbon nanotubes （CNTs） and nano-crystalline diamonds was realized by an acetylene chemical vapor deposition （CVD） method in a local heating system. The heating system only heats the Si substrate without preheating the reaction or carrier gas. At the substrate temperature of 700℃, there is no CNT or clear diamond grain grown on the whole substrate. When the temperature is raised to 740~;, no CNT but many nanodiamonds in the size of tens of nanometers are grown on the area of patterned iron film. At 770℃, there are many nanodiamonds in the size of tens to hundreds of nanometers in the interior of the iron film. Some CNTs are found simultaneously at the edge of the patterned iron film. When the temperature is raised to 850℃, the area where CNTs are grown increased while the average size and density of nanodiamonds decreased. At 910 ℃, a large number of CNTs are grown with an average diameter of 20 nm, which is the same as the CNTs grown by a conventional thermal CVD. It is speculated that at a lower substrate temperature, the surface catalytic reactions are predominant, which induces the formation of sp3^-stmctured nanodiamonds. With the increase of the substrate temperature, the gas surrounding the substrate is heated up to the temperature of its gas-phase self polymerization, and then forms the unsaturated hydro- carbon chains, which are considered to play an important role in the growth of sp2-structured CNTs.
出处
《纳米技术与精密工程》
EI
CAS
CSCD
2009年第2期102-105,共4页
Nanotechnology and Precision Engineering
关键词
碳纳米管
纳米金刚石
化学气相沉积
制备
carbon nanotube （CNT）
nanodiamond
chemical vapor deposition
synthesis
