Fabrication of nanoscale heterostructure devices with a focused ion beam microscope

A focused ion beam (FIB) microscope has been used to fabricate junctions with dimensions in the range 100–5000 nm by three-dimensional etching. We have applied this process to a variety of structures, including current-perpendicular-to-plane giant-magnetoresistive multilayer devices, superconductor–metal–superconductor Josephson junctions, where the metal is Mo, Co, or a Cu x Ni 1− x alloy, and GaN light-emitting diodes. In addition, Tl 2 Ba 2 CaCu 2 O 8 intrinsic Josephson junctions were also fabricated and characterized. The flexibility of the FIB technique allowed junctions of many different materials and heterostructures to be fabricated with the same process.