Morphological and compositional effects of FIB nanopatterning of multilayer metal/semiconducting devices

In this work, a structural and compositional investigation of the effects of focused ion beam (FIB) nanopatterning of a critical material system was carried out. A pattern of cylindrical holes, with the diameter in the range 50–150 nm, was dug by FIB into the topmost metal layer of an InAs quantum dots based heterostructure, and the effects of the ion beam treatments on the composition of the layers involved in the milling process were evaluated. FIB preparation of transmission electron microscopy (TEM) lamellas provided suitable samples for the chemical analyses exactly from the regions where the holes were dug. Detailed experimental data were obtained by means of scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS), and the effects of implantation, intermixing, redeposition and, more in general, defect creation induced by the Ga ion bombardment evaluated and compared with the results of stopping and range of ions in matter (SRIM) simulations.