Bonn 2010 – scientific programme
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T: Fachverband Teilchenphysik
T 63: Strahlenhärte von Halbleiterdetektoren I
T 63.9: Talk
Tuesday, March 16, 2010, 18:45–19:00, HG ÜR 6
Analysis of the radiation hardness of DEPFET sensors with x-rays — •Peter Müller1,2, Ladislav Andricek1,2, Christian Kiesling1, Christian Koffmane1,2, Hans-Günther Moser1,2, Jelena Ninkovic1,2, Rainer Richter1,2, Andreas Ritter1,2, and Stefan Rummel1,2 — 1Max-Planck-Institut für Physik — 2Max-Planck-Institut für Physik - Halbleiterlabor
In order to upgarde the Belle-Experiment at KEK, DEPFET-sensors (Depleted Field Effect Transistors) will be used for the two innermost layers of the vertex detector. Due to the increased luminosity, expected at Belle-II, these sensors need to resist a significantly higher radiation dose of up to 1 Mrad (10 kGy) per year, meaning 10 Mrad (100 kGy) for the intended working time of 10 years. Ionising radiation creates positive charge carriers that will be collected at the interface between silicon and silicon dioxide. These charge carriers shift the threshold voltage of the scheduled transistors, and so, for a constant handling of the detector, the operating voltage needs to be adjusted. In order to perform the right amount of adjustment, it is crucial to know the change of the threshold voltage, and to be able to predict it correctly.
The radiation was executed at the x-ray facility at KIT (Karlsruhe Institute of Technology) with a maximum photon energy of 60 keV and the test devices were matrices of 6x16 DEPFET-pixels. Changes of the threshold voltages were measured and compared with theoretical models.