Ion beam sputtering for progressive reduction of nanostructures dimensions

An ion beam-based dry etching method has been developed for the progressive reduction of the dimensions of prefabricated nanostructures. The method has been successfully applied to aluminum nanowires and aluminum single electron transistors (SET). The method is based on removal of material from the structures when exposed to energetic argon ions, and it was shown to be applicable to the same sample many times. Electrical measurements, and samples imaged in-between the sputtering sessions, clearly indicated that the dimensions (the cross-section of the nanowires and the area of the tunnel junctions in SET) were progressively reduced without noticeable degradation of the sample structure. We were able to reduce the effective diameter of aluminum nanowires from similar to65 nm down to similar to30 nm, whereas the tunnel junction area has been reduced by 40%.