Thin-film single-walled carbon nanotube transistors fabricated using mechanical meniscus aligned arrays

Abstract

Single-walled carbon nanotubes (SWNTs) are novel carbon nanostructures with unique properties that have made them highly attractive materials for research in nanotechnology. Due to their exceptional electrical, mechanical, optical and structural properties, SWNTs have potential applications in the fields of nanoelectronics, optoelectronics, sensory devices and other areas of nanoscience. However, several challenges need to be addressed before SWNTs can be considered as potential candidates for future nanoelectronic devices. In order to use SWNTs to fabricate high performance nanoelectronic devices on a large scale, it is highly desirable to have precisely placed, high density, aligned arrays of SWNTs having uniform electronic properties. This thesis demonstrates a post-synthesis, mechanical alignment technique to obtain precisely placed, high density, aligned arrays of SWNTs. By using an aqueous solution containing surfactant-encapsulated SWNTs dispersed in it, a meniscus is formed either between a capillary tube and a substrate or between two angled substrates of differing hydrophobicity. As the meniscus is mechanically dragged across the substrate, the SWNTs get pinned to the surface and are aligned by the mechanical torque along the direction of the meniscus drag. The alignment has been characterized on various hydrophilic and hydrophobic substrates and the optimum conditions required for SWNT alignment have been studied. Techniques to eliminate the surfactants from the deposited SWNT networks have also been discussed. Finally, a complementary metal-oxide-semiconductor (CMOS) compatible fabrication process has been used to demonstrate thin-film SWNT field-effect transistors fabricated by using the aligned SWNT arrays as the active channel of the transistor.