Ion beam shadowing effects in SIMS depth profile analysis of MBE-grown nanostructures

The structures were bombarded with several incidence angles. Bombardment at 45° and 70° resulted in strange In+ secondary ion current oscillations registered at the SIMS profile when the sputtering front was passing single 8-nm-thick In0.24Al0.19Ga0.57As layer buried at a depth of 1.59 μm. Ion bombardment at 20° allowed to avoid these oscillations. Secondary electron microscopy (SEM) images of the bombarded surfaces show the presence of several 3D objects including oval defects. We propose attributing these oscillation effects to primary ion beam shadowing by such objects.