Charge collection efficiencies of planar silicon detectors after reactor neutron and proton doses up to 1.6×1016neqcm-2

The planned luminosity upgrade of the large hadron collider at CERN (Super-LHC) will provide a challenging environment for the tracking and vertexing detector systems. The innermost devices at a radius about 4 cm from the interaction region will have to be able to withstand a combined charged and neutron hadron dose in the order of 101610161MeV neutron equivalent particles (neqneq) per square centimeter over the anticipated 5 year lifespan of the SLHC experiments. Planar, segmented silicon detectors with n-strip readout are one of the many radiation tolerant technologies under consideration for use for the Super-LHC tracking detectors in either pixel or strip geometries.This paper details charge collection efficiency measurements made with silicon sensors that have been irradiated to doses as high as 1.5×1016neqcm-2 with reactor neutrons and as high as 1.6×1016neqcm-2 with 26 MeV protons and 24 GeV protons. In this study, n+n+ segmented strip readout in either n-bulk (n-in-n) or p-bulk (n-in-p) substrates are considered. Both diode configurations were processed in substrates grown with float zone (FZ) and magnetic Czochralski (MCz) techniques. For the fluences studied, all the n+n+ strip readout technologies are still viable assuming that adequate bias voltage and cooling can be supplied and low noise, low threshold readout electronics can be designed.