Carbon transistor devices having channels formed from carbon nanostructures, such as carbon nanotubes or graphene, and having charged monolayers to reduce parasitic resistance in un not gated regions of the channels, and methods for fabricating carbon transistor devices having charged monolayers to reduce parasitic resistance. For example, a carbon field effect transistor includes a channel comprising a carbon nanostructure formed on an insulating layer, a gate structure formed on the channel, a monolayer of DNA conformally covering the gate structure and a portion of the channel adjacent the gate structure, an insulating spacer conformally formed on the monolayer of DNA, and source and drain contacts connected by the channel.