Experimental Determination of the Impact Ionization Coefficients in Irradiated Silicon

We present new results on the influence of radiationinduced damage on the electron Impact Ionization (I.I.) coefficient , suggesting a small but distinct reduction of at high fluence with respect to unirradiated silicon. Experiments on thick (1.5 m) and thin (1 m) epitaxial silicon samples confirm that such a reduction of is expected even in cases where impact ionization is not simply a field driven process because of strongly non local transport conditions. A consistent increase on the breakdown voltage of a 3D radiation detector has been evaluated by means of TCAD simulations using the experimentally extracted I.I. coefficient for irradiated silicon. These results clarify the impact of radiation damage on some of the key model parameters for TCAD simulations and allow for improved accuracy toward predictive breakdown simulations of silicon particle detectors, e.g., for the ATLAS experiment

The INFN-FBK pixel R&D program for HL-LHC

International audienceWe report on the ATLAS and CMS joint research activity, which is aiming at the development of new, thin silicon pixel detectors for the Large Hadron Collider Phase-2 detector upgrades. This R&D; is performed under special agreement between Istituto Nazionale di Fisica Nucleare and FBK foundation (Trento, Italy). New generations of 3D and planar pixel sensors with active edges are being developed in the R&D; project, and will be fabricated at FBK. A first planar pixel batch, which was produced by the end of year 2014, will be described in this paper. First clean room measurement results on planar sensors obtained before and after neutron irradiation will be presented