Initially two metal electrodes forming nanogaps are fabricated by standard e-beam lithography. By electrochemical deposition of gold on these electrodes the nanogaps are closed forming gold nanocontacts such as in Fig1.
Fig 1. Fabrication of gold nanocontacts by electrochemical deposition of gold.
Low voltages application on the electrodes gives Ohmic response in the current (as shown in Fig 2(a)). After a certain higher applied voltage, electromigration makes the electrodes open again forming a nanogap which is detected in the I-V loops (fig 2 (d)). Higher applied voltages make the gaps wider and the Coulomb blockage behaviour appears (fig 2 (d)). In order to observe this event it is important the nanocontact is robust enough to support 15V applied voltages without destroying, this is not achieved fabricating thin electrodes because they are easily destroyed during electromigration.
Fig 2. I-V gold nanocontacts and nannogaps
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