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.