The abundance of work on SiGe based devices demonstrates the importance of compositional characterization of such materials. However accurate SIMS depth profiling of SiGe, and especially of SiGe/silicon dioxide interfaces can be difficult due to matrix effects. Therefore, we highlight here the improvements brought by the extended Full Spectrum protocol, presented in previous works and allowing minimization of matrix effects. Previous studies on this protocol showed that it was extremely precise and reproducible for Ge and impurity quantification in non oxidized matrices. In this study we thus investigated its accuracy for simultaneous quantitative depth profiling of both matrix elements (Si, Ge, O) and impurities (C) in Si0.82Ge0.16C0.02 layers annealed in oxidizing atmosphere, by comparing results with more classic protocols. The profiles provided by the extended Full Spectrum protocol were found to be more accurate than the others, especially around interfaces. This results in a better comprehension of the behaviour of SiGeC layers under oxidizing anneal and thus allows the fabrication of very well controlled three dimensional Ge nanowire structures for next generation devices. (C) 2011 Elsevier B. V. All rights reserved.