Electrical characterization of a radiation-hardened silicon pixel design for CMS

We have summarized our R and D on the radiation hardening and handling of high operating voltage for the CMS forward pixel detectors. More radiation-hardened silicon pixel sensors of configuration n sup + /n/p sup + with single-sided multi-guard ring structures have been developed and tested under the radiation environment expected at LHC. In the design, no guard ring is required on the n sup + side and guard rings on the p sup + side are always kept active before and after type inversion. The whole n sup + side is grounded and connected to readout-chip, which greatly simplifies detectors assembling and improves the stability of bump-bonded readout chip on the n sup + side. Samples had been irradiated to high fluence neutron and proton radiations to study the radiation hardness effects. Electrical characteristics such as leakage current, potential distributions over guard rings and full depletion voltage were measured under different temperatures.