Transport through metallic nanogaps in an in-plane three-terminal geometry.

Fabrication of three-terminal nanoscale devices is a key issue in molecular electronics to implement field-effect molecular transistor. We present in this paper two different electromigration procedures to realize metallic nanogaps at room and liquid helium temperature. A room temperature controlled electromigration process, consisting of a gradual thinning of a nanowire until the formation of a one channel contact, gives the best yield of bare nanogaps, i.e., gaps with a tunneling-like behavior. At low temperature and for a not fully controlled electromigration process, metallic clusters may remain inside the nanogap. An in-plane side gate electrode coupled to the nanogap allows transport measurements as a function of the gate voltage. Using this external tool we investigate the properties of the nanogaps, showing how clusters can mimic molecular behavior. [ABSTRACT FROM AUTHOR]