THE EFFECT OF METAL FIELD PLATES ON MULTIGUARD STRUCTURES WITH FLOATING P+ GUARD RINGS

The performance and stability of silicon diode detectors can be improv ed by implementing guard ring structures around the active detector ar ea. The purpose of this work is to study design parameters influencing the performance of multiguard structures, especially the effect of me tal field plates. An important feature is the potential distribution i n the multiguard ring structure which depends on the bulk doping conce ntration, the oxide charge, the size of the gap between guard rings an d the field-plate design. We have made a systematic investigation of t he effect of distance between floating p(+) guard rings with two diffe rent metal field plate designs. We have also varied the width of the f ield plates and studied the effect of gamma irradiation. Numerical sim ulations have been done to compare with results from the experimental potential distributions between guard rings.