Product Code: PIC2008_M1203

Fabrication of Carbon Nanotube Interconnections by Current-assisted Laser Irradiation
Authors:
Tao Gong, Tsinghua University, Dept of Mechanical Engineering; Beijing Peoples Republic of China
Yong Zhang, Tsinghua University, Dept of Mechanical Engineering; Beijing Peoples Republic of China
Chaofeng Wu, Tsinghua University; Beijing Peoples Republic of China
Minlin Zhong, Tsinghua University; Beijing Peoples Republic of China
Wenjin Liu, Tsinghua University, Dept of Mechanical Engineering; Beijing Peoples Republic of China
Jinquan Wei, Tsinghua University; Beijing Peoples Republic of China
Yi Jia, Tsinghua University; Beijing Peoples Republic of China
Kunlin Wang, Tsinghua University; Beijing Peoples Republic of China
Dehai Wu, Tsinghua University; Beijing Peoples Republic of China
Presented at PICALO 2008

The unique mechanical and electronic properties of carbon nanotubes (CNTs) have stimulated great interests in their potential usage in many fields. The fabrication of circuits or nanomechanical devices based on CNTs requires a technique to connect the CNTs electrically and mechanically with each other and with their periphery. As a promising approach, some present work explores the possibility to join CNTs by forming an aggregate of amorphous carbon by electron beam in an electron microscope. However, since the efficiency of this electron-beam-induced deposition (EBID) method is very low, it can hardly be used for the fabrication of large-scale circuits or devices. In this paper, we report a new technique to fabricate a large number of interconnections between double-walled carbon nanotube (DWNT) bundles and even between DWNT bundles and multi-walled carbon nanotubes (MWNTs) by laser irradiation. A purified ultra-thin DWNT film was first spread and transferred to a mica-wafer in order to provide a perfect network consisting of many crossed DWNT bundles for laser processing. A 25W CO2 laser (beam diameter is about 4mm) was employed and a direct current was passed through the film during the treatment. TEM observation showed that, after current-assisted laser irradiation, many interconnections were formed between the crossed DWNT bundles, which were further proved to be an aggregate of amorphous carbon by HRTEM. By dropping the MWNT/acetone solution on the film before processing, interconnections between DWNT bundles and MWNTs can be formed in the same way. The above fabrication of interconnections can be considered as a result of aggregate and successive transformation of hydrocarbons into amorphous carbon under the energy input of both current-induced high temperatures at the crossing spots and laser irradiation, which also happens in the EBID processing. The electronic properties of the interconnections were also investigated by comparing the resistance characteristics of the DWNT film before and after treatment.