PoS(RD11)031 Irradiations on DEPFET-like test structures Andreas Ritter * a , Ladislav Andricek a , Teresa Hildebrand c , Christian Koffmane a,b , Hans-Günther Moser a , Jelena Ninkovic a , Rainer Richter a , Gerhard Schaller a , and Andreas Wassatsch a a Halbleiterlabor, Max-Planck-Institut für Physik und Max-Planck-Institut für extraterrestrische Physik Föhringer Ring 6 80805 München Germany b Faculty of Electrical Engineering & Computer Science, Sensor & Actuator Systems, TU Berlin Einsteinufer 19 10587 Berlin Germany c PNSensor GmbH Römerstr. 28 80803 München Germany For the upgrade of the Belle detector at KEK DEPFET pixels (Depleted p-channel field effect transistor) are foreseen for the two innermost layers of the vertex detector. As a MOS device, the DEPFET is susceptible to ionizing radiation, which will be created near the interaction point. Ionizing radiation damages the silicon dioxide and alters the operating characteristics of the tran- sistor. The DEPFET exhibits two gate contacts (gate and clear gate) and the final sensor may have a relatively complex pixel layout. In this layout several potential configurations for the clear gate contact exist. As the radiation damage depends not only on the dose, but also on the electric field in the gate oxide, several test structures, which correspond to different clear gate designs, have been irradiated with x-rays. This paper presents measurements and results from irradiation campaigns and show the influence of a variable silicon nitride layer deposited on top of the silicon dioxide. 10th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors, July 6-8, 2011 Firenze Italy * Speaker. c  Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/