Separation Of High-purity Semiconducting Single-walled Carbon Nanotubes And Its Properties

Single-walled carbon nanotubes(SWNTs)are considered a strong competitor to next-generation semiconductor materials with their unique structure and electronic properties.However,as-synthesis SWNTs are mixture of metallic(m-)and semiconducting(s-)SWNTs,which limits its application in the electronics field.How to achieve high purity separation of semiconductor SWNTs largely determines their potential in the field of electronics applications.The purity of s-SWNTs separated by conjugated polymer selective dispersion can be more than 99.9%,and it has the advantages of high efficiency and high volume,which is the mainstream of s-SWNTs separation technology.However,the electrical properties of sorted s-SWNTs are still far from the intrinsic electrical properties of carbon nanotubes.This paper focuses on how to solve the main problems in the application of s-SWNTs in micro-nanoelectronic devices,including the reduction of defects on carbon nanotubes during the separation process,the improvement of the purity of the s-SWNTs,the removal of polymers on the surface of s-SWNTs,the high homogeneity of network films and the realization of high performance thin-film transistors(TFTs).The main results are as follows:1.Achieving high efficient separation of s-SWNTs by PCz polymer.First studied the effect of the molecular weight of the polymer.It was found that the molecular weight had a great influence on the separation yield,but the effect on the purity not obvious.Then,combined with absorption spectroscopy,Raman spectroscopy and statistical of s-SWNTs length,studied the competitive relationship between the defects of s-SWNTs,and the purity,yield of s-SWNTs by means of detailed optimization of ultrasonic and centrifugation.The final optimized condition can obtain s-SWNTs with a purity of 99.99% and minimize the defects caused by the separation process.2.Developed a simple and easy-to-achieve method to removing polymer from the surface on carbon nanotubes and more than 99% of the polymer dispersants are removed.While still retaining the monodispersity and stability of s-SWNTs in the solution.Based on the s-SWNTs solution after cleaning,a large area of s-SWNTs films can be prepared rapidly,and the density and homogeneity of the films are greatly improved.The contact between the carbon nanotubes and the carbon nanotubes was greatly improved due to the removal of the dispersants,and the current density of the thin film devices prepared by s-SWNTs after cleaning was increased by three times and the contact resistance was reduced to 17%.3.Developed a surface treatment process compatible with semiconductor processing technology by introducing plasma dry etching technology to improve the contact between s-SWNTs and electrodes in the process of s-SWNTs TFT preparation.The optimized current density of device is doubled;and mobility is up to 91 cm2V-1s-1,which is the highest performance of transistors in current network s-SWNTs TFTs.