A new approach to the optimal design of multiple field-limiting ring structures

In this paper, a computer-based analysis is performed to study layout solut ions aimed at increasing the breakdown voltage in Si-microstrip detectors. For optimum performance it is crucial to achieve maximum breakdown voltage for Si detectors operating at very high bias due to the extremely hostile r adiation environment of next generation experiments such as LHC. The perfor mance of Si-microstrip detectors can be improved by implementing floating f ield-limiting rings around the active detector area. A simulation study has been carried out to evaluate the distribution of breakdown voltage as a fu nction of guard-ring spacing (GS). The purpose of this work is to find a cr iterion to optimize GS for multiple ring structures incorporating various p hysical and geometrical parameters as an aid to design optimization. Using this criterion the optimum spacing of guard rings for multiple ring structu res was obtained. The proposed criterion is very robust and is insensitive to the number of guard rings, junction depth and radiation damage. The simu lation results for the seven-ring design agree well with experimental measu rements.