Study On The Growth Methods Of Chiral Cntrollable Single-walled Carbon Nanotubes

Single walled carbon nanotubes(SWNTs)have been one of the research hotspots in the field of nanoscience since it was found in 1993,mainly due to its perfect conjugated tubular structure and excellent physical and chemical properties.This makes it not only have potential application value in the field of composite materials,but also have broad application prospects in the field of energy,battery,biosensor and nanoelectronics.Especially in the field of nanoelectronics,SWNTs based electronic devices are considered to be one of the best candidates to replace silicon-based electronic devices.At present,many single-walled carbon nanotube based devices have been realized,such as memory,sensor,display,etc.,and even computers made of carbon nanotube have been published.However,the improvement of device performance often depends on the carbon nanotube material itself,and the control of carbon nanotube structure is the biggest obstacle to its application in the field of nanoelectronics.Therefore,how to obtain single structure and prepare SWNTs with mature technology is the ultimate challenge in this field.In this thesis,we mainly focus on catalyst and temperature to solve the application problems of SWNTs in the field of nano electronic devices and computer chips in the future,and develop the preparation methods of chiral controllable SWNTs.(1)Growth of single-walled carbon nanotubes with single-layer disulfide: in this experiment,from the perspective of catalyst design,the problem of catalyst aggregation in the growth process was solved.A new catalyst,molybdenum carbide,was proposed and designed.This catalyst has a high melting point and is not easy to aggregate in the growth process.Finally,the single chiral SWNTs was successfully prepared(13,12).A field-effect transistor was constructed for this carbon nanotube,and using this carbon nanotube to construct a field-effect transistor,the number of devices with a switching ratio> 10 is as high as 97%.At the same time,another catalyst,tungsten carbide,was designed,and finally single chiral(16,9)carbon nanotubes were successfully grown.Using this kind of chiral carbon nanotubes to construct field-effect transistors,it was found that the content of semiconductor carbon nanotubes was more than92%.This design method of high melting point catalyst overcomes the problem of aggregation in the growth process of traditional low melting point catalyst,and provides a new research method for controllable preparation of single chiral carbon nanotubes.(2)Growth of single-walled carbon nanotubes with narrow chiral distribution at low temperature: in this experiment,from the perspective of temperature design,we have successfully prepared narrow chiral(9,6)and(13,1)carbon nanotube arrays on sapphire substrate by the method of "pyrolysis at high temperature,growth at low temperature".The mode of high temperature cracking and low temperature growth not only improves the growth efficiency,but also ensures that the crystal structure of the catalyst is stable in the growth process;the suitable support can expose and stabilize the required crystal surface of the catalyst,and use it as a template to control the structure of carbon nanotubes;the specific crystal surface of the catalyst and low temperature two factors reduce the chiral range of carbon nanotubes.It also provides a new idea for the study of growth methods of chiral SWNTs...