Simulation of new p-type strip detectors with trench to enhance the charge multiplication effect in the n-type electrodes

This paper shows the simulation results of new p-type strip detectors with trench electrodes to enhance the charge multiplication effect in the irradiated detector. The new design includes baby microstrip detectors (area=1 cm2) with a strip pitch of 80 μm and p-stop isolation structures. The strip has a 5 μm-wide trench along all its length, filled and doped with polysilicon to create a deep N+contact into the material bulk. The trench depth can be varied in order to study the influence of the electric field on the charge multiplication effect in heavily irradiated samples. Some alternative designs have also been studied to establish a comparison between various structures using different technologies. Simulation reproduce the electrical behaviour under different irradiation conditions, taking into account the damage accumulated after irradiation with neutrons and protons with several fluence values. The investigation of these effects provides important indications on the ability of this modified electrode geometry to control and optimise the charge multiplication effect, in order to fully recover the collection efficiency of heavily irradiated microstrip detectors, at reasonable bias voltage compatible with the voltage feed limitation of the CERN SLHC experiments.