| First proposed in the late 1990's, a nanomechanical electron shuttle is a device where an electrically isolated island moves a definite number of electrons between two leads, producing a current that is directly related to the number of electrons moved in a cycle and to the vibration frequency of the island. Since nanomechanical structures can have very well defined vibration frequencies, a device of this type is useful as, among other things, a current standard for metrology. The experimental shuttle implementations to date have had large island-lead spacings, which has limited their performance. The work presented here takes the first steps towards the fabrication of a nanomechanical electron shuttle using the process of electromigration to define very small lead-island gaps with conductivity on the order of the conductance quantum G0 = 2e2/ h. These small gaps, coupled with the high vibration frequencies achievable with nanostructures, will allow investigation deeper into the realm of quantum effects.;In this work, the fabrication steps for the creation of these devices were developed. Electromigration of a single junction was successfully achieved to the 10--100 kO range. The simultaneous and symmetric electromigration of two junctions, as required for the shuttle, has not yet been achieved. The development of a fast electromigration cut-off circuit, however, gives hope that double-breaking success will be achieved soon. |
