Masked ion damage and implantation for device fabrication

Abstract

Several groups have recently demonstrated junction formation by masked ion damage in which ions from a broad beam ion source locally damage regions of superconductor to form the junction barriers. However, the difficulties of preparing successful mask structures have meant the progress to date has been relatively slow. Using masks of high electron density metals such as Au and protons as the irradiating species, we have shown in a series of studies that irradiation of YBa 2Cu 3O 7− δ (YBCO) with ions of energy in the range of 30–350 keV can be used to create highly localised damage regions in the films. This technique has been successfully employed to create high quality Josephson junctions in YBCO. The fabricated devices show clear dc and ac Josephson effects. This technique is very promising in terms of simplicity and flexibility of fabrication and has potential for high density integration.