A shadow mask method to fabricate electrodes with nanometer scale separation
utilizes
nanotubes (NTs). Metal wires with gaps are made by incorporating multi-wall carbon
nanotubes (MWNTs) or single-wall carbon nanotubes (SWNTs) (or bundles thereof)
into a tri-layer electron beam lithography process. The simple, highly controllable,
and scaleable method can be used to make gaps with widths between 1 and 100 nm.
Electronic transport measurements performed on individual SWNTs bridge nanogaps
smaller than 30 nm. Metallic SWNTs exhibit quantum dot behavior with an 80 meV
charging energy and a 20 meV energy level splitting. Semiconducting SWNTs show
an anomalous field effect transistor behavior.
