Synthesis of ultralong and high percentage of semiconducting single-walled carbon nanotubes

Two main results are reported here for single-walled carbon nanotubes (SWNTs) synthesized from well-controlled isolated catalytic Fe2O3 nanoparticles. The first is patterned growth of ultralong SWNTs (lengths up to 0.6 millimeters) by using a mixed methane and ethylene carbon source in chemical vapor deposition (CVD). Interesting loop and closed ring structures similar to those of fullerene crop circles are observed on these as-grown ultralong tubes. Second, surveying the electronic properties of individual SWNTs by transport measurements reveals that approximately 70% of individual SWNTs grown from isolated nanoparticles are semiconductors exhibiting field effect transistor (FET) characteristics. The distribution of CVD-grown SWNT chirality is elucidated for the first time, and implications to array-based nanotube electronics and sensors are discussed.