Gigahertz integrated circuits based on carbon nanotube films

Progress in the controlled synthesis and post-growth treatment of carbon nanotubes has led to the fabrication of nanotube-based field-effect transistors with intrinsic performance close to the ballistic limits. However, nanotube-based integrated circuits (ICs) developed to date typically have a working frequency of less than 1 MHz, which is well below the working frequency of silicon ICs. Here we show that the speed of carbon nanotube ICs can be significantly improved by optimizing device structure and fabrication processes, yielding ICs that work in the gigahertz regime. Based on high-performance nanotube film field-effect transistors, five-stage ring oscillators were batch fabricated and shown to exhibit an oscillation frequency of up to 5.54 GHz. This is twenty times higher than that of the leading nanotube IC (a five-stage ring oscillator with an oscillation frequency of 282 MHz).