Reduced tunnel-barrier height in sub-10 nm Au nanoelectrodes

This paper presents a selective-etch fabrication process to create vertical sub-10 nanometre metallic gaps and the subsequent characterisation of the gaps by scanning electron microscopy and electrical measurements at low temperature. Before the electrodes are used to study the electrical properties of nanocrystals or molecules, the behaviour of the empty gaps must be examined. The I-V characteristics of the empty gaps showed a marked reduction of the tunnel barrier heights from the vacuum level when the results were fitted to the Simmons tunnelling model for a metal-insulator-metal system and when the values were extracted from Fowler-Nordheim plots.