Self-aligned gate dielectric in carbon nanotube field-effect transistors by anodic oxidation of aluminium

We demonstrate a process of fabricating carbon nanotube field-effect transistors with self-aligned gate insulators by anodic oxidation of aluminium. We use rapid thermal annealed multi-walled carbon nanotubes (CNTs) as the active material overlaid across an aluminium gate. The porous nanotube bundles allowed moisture from the air to penetrate, and oxidise the aluminium by anodic oxidation to construct a self-assembled aluminium oxide in the area where the CNTs were overlaid. Electron dispersive spectroscopy analysis of this oxidised surface confirmed the formation of self-aligned Al₂O₃. The metal-oxide-carbon nanotube transistors were compared to conventional nanotube transistors which have silicon dioxide as the gate insulator. Our results show that the self-aligned gate insulator produced by the anodic oxidisation of aluminium had better transistor performance. This is a promising process for the fabrication of nano-transistors in which embedded nanowires or nanotubes are the functional material in field-effect transistor applications.