Random networks of carbon nanotubes as an electronic material

We report on the transport properties of random networks of single-wall carbon nanotubes fabricated into thin-film transistors. At low nanotube densities (similar to1 mum(-2)) the networks are electrically continuous and behave like a p-type semiconductor with a field-effect mobility of similar to10 cm(2)/V s and a transistor on-to-off ratio similar to10(5). At higher densities (similar to10 mum-2) the field-effect mobility can exceed 100 cm(2)/V s; however, in this case the network behaves like a narrow band gap semiconductor with a high off-state current. The fact that useful device properties are achieved without precision assembly of the nanotubes suggests the random carbon nanotube networks may be a viable material for thin-film transistor applications. (C) 2003 American Institute of Physics.