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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.
The selective growth of carbon nanotubes (CNTs) and diamond crystals has been achieved by chemical vapor deposition (CVD) in a localized heating system, and the heating system heats the silicon substrate only for the reaction process and loading No heating of the gas CNT or significant diamond particles were generated at a substrate temperature of 700 ° C. CNTs were still not formed when the temperature was raised to 740 ° C. However, Nano diamond particles.When the temperature is 770 ℃, a large number of diamond particles with the size of tens to hundreds of nanometers are formed in the central part of the iron film, while some CNTs can be observed at the edge of the iron film.When the temperature reaches At 850 ℃, the growth area of CNTs expands and the average size and the formation density of nano-diamond decrease.A large number of CNTs are formed at the high temperature of 910 ℃ with an average diameter of 20nm, which is the same as the CNTs produced by the usual thermal CVD method At lower substrate temperatures, the surface catalysis dominates and may induce the formation of nanodiamonds with sp3 structures. As the substrate temperature increases, the gas surrounding the substrate is Heat, form an unsaturated hydrocarbon chain which is reached from the gas phase polymerization temperature, the resulting hydrocarbon chain plays an important role in the generation of CNT sp2 configuration.