Compositional analysis of Si nanostructures: SIMS–3D tomographic atom probe comparison

3D atom probe tomography (APT) is introduced as a powerful compositional and spatial analytical tool for SiGe nanostructures. Compositional analysis of SiGe structures demonstrates that the location and identity of Si, Ge and B atoms can be detected in three dimensions. Superior sensitivity at Si–SiGe–Si interfaces is specifically witnessed by both the quantification of Ge accumulation at an interface (14% by atom probe versus 9% by SIMS) and a slope roll-off of ∼1 nm/decade for atom probe compared to ∼7 nm/decade for the corresponding SIMS analysis. Additionally, APT provides chemical roughness measurements of buried interfaces. In a specific case, a Si–SiGe–Si interface had a measured roughness of 0.47 nm at the Si–SiGe leading edge and 0.26 nm at the SiGe–Si trailing edge. (Some figures in this article are in colour only in the electronic version)