Single-sided microstrip detector for high radiation doses

A “single-sided” microstrip detector with n-type strip implants in n-type silicon substrate materials has been developed for use in high luminosity vertex tracker experiments. This technology has been chosen to make a detector which will operate satisfactorily well beyond the radiation dose which converts the substrate to p-type material. This full-size detector of dimensions 60 mm × 60 mm has 1025 strips (with 512 read-out strips) biased with polysilicon resistors. Separate “p-stop” implants between the strips isolate the strips from each other electrically. These individual p-stops are implemented in order to reduce the detector noise. A combination of silicon oxide and silicon nitride gives a very reliable dielectric layer for the coupling capacitors, which yields a low fraction of defective read-out strips. The backside p-n-junction area is surrounded by a high-stability guard which makes it possible to operate the detector at bias voltages corresponding to several times the depletion voltage. Preliminary irradiation tests carried out in order to determine the detector design's suitability for the experiments at the CERN-Large Hadron Collider have shown that the detectors are not fatally damaged after a radiation dose of 2 × 1014 protons cm−2.