Resistivity variations in ion implanted silicon detectors

Ion-implanted silicon detectors which are specially developed for timing experiments show timing response variations of a few times 100 ps as a function of the position of the detector. These variations are caused by resistivity fluctuations up to 50%. To quantify these resistivity variations, depletion depth studies have been performed for a set of detectors. The timing results are obtained with a high-resistivity overdepleted detector. Different detectors are produced from one wafer. Some of these detectors show very low resistivity variations (10%) whereas others show strong resistivity variations (50%). No correlation between the originating place on the wafer and the magnitude of the resistivity variations has been found yet. Therefore, detectors should be scanned at least for homogeneous depletion depth to ensure homogeneous behavior when optimum performance in time of flight experiments and pulse shape experiments is desired