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HK: Fachverband Physik der Hadronen und Kerne
HK 39: Instrumentierung - Poster
HK 39.28: Poster
Wednesday, March 23, 2011, 14:00–16:00, Foyer Chemie
Understanding radiation damage in silicon sensors for the CBM silicon tracking system through transients — •Sudeep Chatterji1 and Minni Singla2 — 1GSI Darmstadt — 2Goethe University Frankfurt
From TCAD simulations, it has been found that Double Sided silicon Strip Detectors for the CBM STS will have to be operated under-depleted as their full depletion voltage (VFD) will become higher than their breakdown limit due to high radiation environment. In order to investigate the strip isolation on the ohmic side after irradiation, we have simulated transients of Minimum Ionizing Particles passing through DSSDs. To simulate the transients we have used Sentaurus Device and Sentaurus Workbench. From the bias dependance of the signal amplitude, one can sketch the complete post-irradiation behaviour of sensors in terms of charge collection efficiency (CCE), charge sharing and strip isolation. The strip isolation has also been examined in terms of interstrip capacitance (Cint) and interstrip resistance (Rint). It has been found that Rint increases with fluence (φ) before type-inversion while it decreases with φ after type-inversion. However even after maximum expected φ, the Rint of irradiated sensors is higher than of pre-irradiated ones although Cint increases with φ. This means that the DSSDs will have strip isolation on the ohmic side even after maximum φ though they will be more noisy. The simulated results have been compared with a radioactive source scan of DSSDs in terms of CCE, charge sharing and strip isolation. Supported by GSI, HIC for FAIR, EU FP7 Hadronphysics2.