Abstract

Random networks of as-grown single-walled carbon nanotubes (CNTs) contain both metallic (m-CNTs) and semiconducting (s-CNTs) nanotubes in an approximate ratio of 1: 2, which leads to a trade-off between on-conductance and the on/off ratio. We demonstrate how this design problem can be solved with a realistic numerical approach. We determine the CNT density, length, and channel dimensions under which CNT thin-film transistors simultaneously attain on-conductance higher than 1 mu S and an on/off ratio higher than 10(4). The fact that asymmetric systems have more pronounced finite-size scaling behavior than symmetric systems allows us additional design freedom. A realization probability of the desired characteristics higher than 99% is obtained for the channels with aspect ratio L-CH/W-CH < 1.2 and normalized size L-CH W-CH/l(CNT)(2) > 250 2 when the CNT length is l = 4-20 mm CNT and the normalized density of CNTs is close to the value where the probability of percolation through only s-CNT pathways reaches its maximum.