A number of bars grown by CZ, with p-and n-type dopant, have been examined in order to verify that both macroscopic and microscopic segregation of Oxygen atoms is governed by a distribution coefficient higher than 1. The short range non uniformity of 0-atoms concentration has been revealed by preferential etching and spreading resistance measurements, the long range one by IR spectroscopy. A few degrees off orientation of cut slices enabled (as in the case of a beveling angle in junction structures) to expand the radial abscissa and to separate with a better definition the zones of higher 0-concentration. Using such a method, a shape of the profile of the S-L interface can be defined, at any point of the bar.