A Direct-Write Approach for Carbon Nanotube Catalyst Deposition

Nanowriting was used to directly pattern carbon nanotube (CNT) catalyst solution with a scanning probe microscope. Glass nanopipettes filled with iron-based catalyst solutions were scanned in predefined patterns using contact mode atomic force microscopy on silicon/silicon dioxide substrates to create nanoscale catalyst surface distributions. Chemical vapor deposition using methane feedstock at 900°C produced single-walled CNTs in the patterned regions. Examination of patterning and growth conditions provided insight into the catalyst nanowriting process and the associated CNT growth. Two-terminal electronic transport measurements of the nanotube samples showed a typical resistance of 1 M¿. The nanowriting technique allows precise nanoscale catalyst patterns of almost arbitrary geometry to be directly defined for CNT growth in a simple and inexpensive manner suitable for device prototyping and applications.

I. Introduction

Carbon nanotubes (CNTs) have generated tremendous interest across many fields [1]. In particular, these nanostructures are ideal candidates for enhancing electronic devices [2]. Nevertheless, despite progress in understanding CNT growth [3], the lack of precise control over single-walled carbon nanotube (SWNT) chirality, diameter, and positioning remains a major challenge for full scale integration of CNTs in electronics and thus many studies on controlling nanotube growth are being pursued [4]–[12].