Empa’s Electron Microscopy Center is offering a PhD position for investigating complex interfaces in nanostructured Si/GaAs devices for novel semiconductor applications. Focus of the project lies in the analytical and atomic-scale characterization of the heavily strained interfaces between Si pillars onto which GaAs is deposited epitaxially. Particular tasks to be addressed are the investigation of domain formation in GaAs due to possible interface imperfections, identification of atomic scale steps at the interface, the 3D strain analysis of these complex hetero-nanointerfaces, as well as identification of the critical stress before plastic relaxation occurs. High resolution X-ray diffraction methods will additionally be applied for the interface / layer strain and defect characterization. Synergies between TEM and HRXRD will be exploited.