酸氧化掺金方法改善碳纳米管的电接触特性

Improvement on electrical contact characteristics of Au-doped carbon nanotubes by acid oxidation

采用硝酸回流方式在碳纳米管表面构造缺陷及含氧官能团,处理后的碳纳米管在氯金酸溶液中超声震荡,经过氢气热还原将氧化态的金还原为0价态的金.扫描电子显微图片及红外吸收光谱表明酸处理成功地在碳纳米管管壁及端部构造了缺陷及羟基、羧基等含氧亲水官能团.形貌表征表明在碳纳米管管壁尤其是端部成功地掺杂了纳米粒子,并且X射线光电子谱表明该纳米粒子是0价态的金.掺杂后碳纳米管的拉曼光谱中G带波数增大说明对碳纳米管掺杂金为P型掺杂.采用介电电泳法分别将碳纳米管原样与掺金碳纳米管样品组装到金电极之间,掺杂使碳纳米管与金电极之间的接触电阻得到明显的降低,电阻值平均降幅高达69.20%.

Defects and some oxygen-containing functional groups were obtained on the surface of carbon nanotubes by means of reflux treatment of 40% nitric acid, and then the treated nanotubes adsorbed the molecules or the corresponding ions by means of ultrasonic vibration in the auric chloride acid solution.The gold in the oxidation state was converted to the 0 valence state through hydrogen thermal reduction.Both of scanning electron microscopy images and infrared absorption spectroscopy show that the defects,some hydroxyl groups, carboxyl and other oxygen-containing functional groups are formed on the walls of the tubes by the acid treatment. Morphological characterization images show nanoparticles are successfully doped on the nanotubes’ walls and ends. X-ray photoelectron spectroscopy shows that the nanoparticle is composed of 0 valence gold. After doping, the G-band wavenumber increases in Raman spectra, which indicates the doping method is P-type, and electrons transfer from adjacent carbon atoms to dopants,increasing the hole concentration in carbon nanotubes and thereby lowering the contact resistance. Both intrinsic carbon nanotubes and treated ones are assembled onto the gold electrodes by dielectrophoresis.Results show that the contact resistance has been considerably improved after doping, with the average resistance decrease up to 69.20%.