Characterization of prototype BTeV silicon pixel sensors before and after irradiation

We report on measurements performed on silicon pixel sensor prototypes exposed to a 200-MeV proton beam at the Indiana University Cyclotron Facility. The sensors are of n/sup +//n/p/sup +/ type with multiguard-ring structures on the p/sup +/-side and p-stop electrode isolation on the n/sup +/-side. Electrical characterization of the devices was performed before and after irradiation up to a proton fluence of 4/spl times/10/sup 14/ p/cm/sup 2/. We tested pixel sensors fabricated from normal and oxygen-enriched silicon wafers and with two different p-stop isolation layouts: common p-stop and individual p-stop.