Controlled deposition and alignment of single-walled carbon nanotubes on solid substrates by self-assembly

Abstract

Carbon nanotubes (CNTs) have been intensively investigated because of their remarkable physical and chemical properties. However, for CNTs to become viable for practical device applications, efficient assembly, integration and deposition of CNTs are required. Although many efforts have been made to pattern CNTs on substrates including selective growth on prepatterned metal catalysts, selective adsorption on surface modified substrates, these approaches still have many limitations and are hard to apply directly to practical devices. In this work, single-walled carbon nanotubes (SWNTs) were deposited on various substrates by chemical and physical interaction. Chemically oxidized and size-controlled SWNTs were prepared by acid treatment. Then, we modified ITO glasses with aminopropylsilane, and fabricated single-walled carbon nanotube multilayer on ITO glasses using condensation reaction between carboxylic acid groups of SWNTs and amino groups of aminosilane. SWNTs were also selectively deposited physically on the prepatterned solid substrates using microcontact printing method and dip coating. Field emission properties of patterned SWNTs on ITO glass were measured and there exists a cold electron emission from SWNTs. The techniques used in this study are preferable because ITO glass is widely used in electronic devices, the substrates can be selectively functionalized without intermediate chemical steps, and the whole process is quite rapid. Therefore, this approach shows the potential for CNT field emission arrays to be fabricated directly on ITO glasses without intricate chemical steps.