Edge effects of radiation damaged silicon pad diodes

Edge effects for square p+n silicon pad diodes fabricated on high-ohmic silicon are investigated. Using capacitance-voltage measurements of two pad diodes with different areas and 320 μm thickness, the planar and the edge contributions to the diode capacitance are determined. For the non-irradiated pad diodes the doping profile is determined. The results with and without edge corrections differ significantly. Without edge correction the value of the bulk doping determined increases by up to 30 % over the depth of the diode, with edge correction it is uniform within ±1.5 %, which agrees with expectation. Edge corrections are determined both for non-irradiated diodes and for diodes irradiated to a fluence of 2.4 . 10¹⁵ n_eq/cm² with 24 GeV/c protons. The edge correction for irradiated diodes is found to be larger than for non-irradiated ones.