Oxygen induced stacking faults (OSFs) are mainly seen in oxygen rich wafers from the seed end of Cz-silicon crystals. In wafers this ring shaped OSF-region delineates a border between two defect regions; usually silicon self-interstitials dominate outside and vacancies inside this ring. High temperature treatment (> 800 degrees C) leads to oxygen precipitation in the border region. These precipitates act as nucleation sites for stacking faults. The standard procedure for characterizing the OSF-rings is to expose an oxidized sample to a preferential etchant, e.g. the highly toxic Wright solution. In this work photoluminescence-imaging is compared to preferential etching and visual inspection. Vertical samples from an n-type Cz-crystal containing an OSF-boundary are studied before and after wet oxidation. High resolution PL-images, which allow for a close inspection of the OSF-area, reveal a complex band-structure of this border region. (c) 2013 Elsevier B.V. All rights reserved.