In this work a summary of complementary approaches to quantitatively characterize ultra shallow dopant distributions in Si, developed within an European multi- laboratories consortium (ANNA), is reported. Results obtained with several techniques on arsenic and boron ultra low energy (0.5-5 keV for As and 0.2-3 keV for B) implants in Si are described. The employed techniques were SIMS, GIXRF (with either conventional or synchrotron radiation excitation), NAA, MEIS, Z-contrast ADF-STEM and spectroscopic ellipsometry. The cross comparisons of dose measurements, dopant distribution and damage build-up behaviour enabled a detailed characterization of the implanted samples and identified the overlap of information from each analytical techniques.