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 (∼1 μm−2) the networks are electrically continuous and behave like a p-type semiconductor with a field-effect mobility of ∼10 cm2/V s and a transistor on-to-off ratio ∼105. At higher densities (∼10 μm−2) the field-effect mobility can exceed 100 cm2/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.