Note: Controlled fabrication of suspended metallic vacuum tunneling gaps

We developed a new fabrication technique for the realization of nanogaps using conventional lithography and in situ controlled thermal evaporation. A 20-40 nm gap between two suspended metallic electrodes is shrunk down to about 1 nm using controlled thermal evaporation. It is demonstrated that with this technique rigid and stable metallic vacuum tunneling junctions can be consistently produced. The fabricated nanogaps were characterized by I-V measurements and their gap sizes and barrier heights were interrogated using the Simmons' model.