Operation of guard rings on the ohmic side of n(+)-p-p(+) diodes

Detectors from high-resistivity p-type silicon with multi guard rings struc ture located on the ohmic side have been investigated. The processed detect ors were constructed with four p(+)-rings surrounding the central p(+)-pad. The n(+)-p junction opposite to the contact with rings had not any protect ion and was cut-through by chip scribing. Investigation of the potential di stribution between the floating p(+)-rings has shown that the potential dif ference arises just after the depletion of the detector bulk and is accompa nied by the detector leakage current saturation. The saturated current is m ainly a leakage current flowing in a scribed periphery. Grounding of one of the p(+)-rings to collect the detector leakage current allows the separati on of the bulk and the surface components of the current, which reduces the current of a central p(+)-pad contact down to tens nA/cm(2). A model based on the field effect in the gap between the neighboring p(+)-rings is propo sed. The experiments carried out in this study show that construction of th e ohmic side of Si detectors with multi guard rings is a perspective approa ch to design the detectors operational at high biases. Detectors processed in this way allow one to apply biases up to 600 V. (C) 1999 Published by El sevier Science B.V. All rights reserved.