Controlled Fabrication Of Semiconducting Single-walled Carbon Nanotubes Arrays

Single-walled carbon nanotubes(SWNTs)have excellent properties such as high mobility,excellent stability and excellent short channel control.Therefore,as the latest ideal channel materials in the 21 st century,they can be widely used in high-performance field effect transistors(FETs),integrated circuits and related electronic devices.However,the SWNTs currently grown in situ have different types of conductive properties,which can be divided into metallic single-walled carbon nanotubes(m-SWNTs)and semiconducting single-walled carbon nanotubes(s-SWNTs),where the presence of m-SWNTs in carbon nanotube devices can lead to high leakage currents and incorrect logic functions.Therefore,how to obtain ultra-high purity s-SWNT arrays is currently the key to realizing the application of SWNTs in nanoelectronic devices in the future.The research work of this thesis mainly starts from the perspective of modifying m-SWNT,and develops a selective free radical chemical modification method to prepare high-purity s-SWNT array.The main content is divided into the following parts:(1)In this section,a method of covalent modification of methyl radicals was developed to control the preparation of SWNT arrays with a content of s-SWNT as high as 97.5% based on the difference in the electronic density of states at the Fermi level of s-SWNTs and m-SWNTs.Meanwhile,s-SWNT film can also be synthesized by this method.Finally,the introduction of the annealing method confirmed the reversibility of the reaction.(2)The content of this part mainly uses the same reaction principle as the methylation method,and adopts a simpler and faster photophenylation reaction in experiment.By changing the electrical properties of m-SWNT,a SWNT array with 97.5% s-SWNT content was successfully synthesized.At the same time,the phenylated SWNT can be thermally reduced to the original SWNT after annealing,which reflects the reversibility of the photophenylation reaction.(3)Mask-assisted phenylation method to prepare SWNT intramolecular junction: This part mainly uses the mask-assisted phenylation method to achieve partial reaction to m-SWNT,thereby achieving the controllable preparation and positioning preparation of SWNT intramolecular junction.Electrical tests show that the intramolecular junction has a strong gate-dependent rectifying behaviour and photoresponse.