Random networks of carbon nanotubes optimized for transistor mass-production: searching for ultimate performance

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 μS and an on/off ratio higher than 104. 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 and normalized size when the CNT length is and the normalized density of CNTs is close to the value where the probability of percolation through only s-CNT pathways reaches its maximum.