Patterning Local Dielectrics and Gates on Carbon Nanotubes

We have patterned local dielectric films and local top gates on carbon nanotube devices. The nanotubes were grown by chemical vapor deposition, and the top insulating layer is patterned locally by electron beam exposure of a spin-on glass (SOG) film. After development the exposed SOG film remains, and a 400 C thermal treatment transforms the SOG into SiO2. The nanotubes remain undamaged by the deposition and densification of the SOG. This simple technique allows the fabrication of devices in which only portions of the nanotube are exposed to the ambient, as well as allowing electrically insulated local gates to be patterned by standard lithography. We will report transport measurements on semiconducting nanotube devices before and after dielectric deposition, and discuss the effects of top gates and back gate on the same device.