Experimental Study On Improving Electrical Contact Performance Of Carbon Nanotubes By Doping

Carbon nanotubes(CNTs)have been widely used in micro and nano electronic devices due to their unique mechanical,thermal,optical and electrical properties.However,the high contact resistance between CNTs and metals leads to heat and reduce s the performance and life of these devices.Therefore,it is of great significance to improve the electrical contact performance of CNTs with metal electrodes by doping CNTs with transition metal elements.Nickel was doped on CNTs by electroless deposition,and cobalt was doped on CNTs with metal organic framework(MOF)as a medium.The CNTs were placed in mixed acid solution of nitric and sulfuric acid to introduce hydrophilic groups on the CNTs,in order to make the CNTs easy to be doped with the transition metals.To dope CNTs with nickel,the CNTs were subjected to extra sensitization and activation,and palladium-catalyzed seeds were introduced.The CNTs were dispersed ultrasonically in deionized water,and dropped into the electroless deposition liquid with nickel chloride hexahydrate as main salt and dimethylamine borane as reducing agent,then nickel-doped CNTs were obtained.To dope CNTs with cobalt,the CNTs oxidized in mixed acid solution were dispersed ultrasonically in deionized water and dropped into the metal organic matrix precursor solution with cobalt nitrate hexahydrate and zinc nitrate hexahydrate as main salt and 2-methylimidazole as organic ligand,then MOF@CNTs samples were obtained.The cobalt-doped CNTs were finally obtained after pyrolysis at 800°C for 5 hours under argon atmosphere.Dielectrophoresis was then used to assemble the original and doped CNTs respectively between the gold electrodes,and the contact resistance of CNTs was measured in real time.Results show that mixed acid oxidation treatment can be used to construct defects and introduce hydrophilic groups on the surface of CNTs.The electroless deposition method can successfully dope CNTs with nickel,and cobalt is successfully incorporated into CNTs by using MOF as a medium.The doping types of CNTs with two different metal elements are both P-type.Compared with original CNTs,the contact resistances of nickel-doped CNTs and cobalt-doped CNTs with electrodes are respectively reduced by 71.63% and 66.67%.Therefore,it can be expected to significantly improve the electrical contact performance between CNTs and electrode materials by introducing charge carriers and selecting suitable doped elements which are compatible with electrode materials.Figure 41;Table 9;Reference 92...