According to one aspect of the invention, a semiconducting transistor is described. The channel portion of the transistor includes carbon nanotubes formed on top of an insulating layer which covers a local bottom gate. Source and drain conductors are located at ends of the carbon nanotubes. A gate dielectric surrounds a portion of the carbon nanotubes with a substantially uniform thickness. A local top gate is located between the source and drain conductors over the carbon nanotubes. Lower portions of the local top gate are positioned between the carbon nanotubes as the local top gate forms pi-gates or "wraparound" gates around each carbon nanotube.