Complementary-type graphene inverters operating at room-temperature

Graphene has recently emerged as a promising candidate for a number of electronic applications. However, the fact that graphene is a zero band gap material by nature has raised many questions in terms of graphene's usefulness for digital applications. Several recent experimental studies have demonstrated graphene based inverters, but issues remain, such as, low inverter gain (0.044[1], 0.02[2]) and mismatch between input/output voltage levels[1,2]. Li et al.[3,4] reported top-gated complementary-like graphene inverters exhibiting a gain larger than 1. However, all data were obtained at 77K, and the implementation of a p-type and n-type FET was accomplished by relying on the intrinsic dependence of graphene's transfer characteristics on the supply voltage, an effect that is hardly controllable and that poses major problems for further device optimization. In this paper, focusing on inverter characteristics without attempting to build a highly scaled device, we report the first room-temperature, electrostatic doping controlled complementary graphene inverter with a gain larger than one.