PIN radiation detectors and other test-structures have been fabricated on FZ high-resistivity (2 kΩ cm), N-type silicon substrate by a planar process that features three different alternative extrinsic-gettering techniques. Extremely low leakage-current values have been measured for these devices, confirming the effectiveness of gettering procedures. In particular, phosphorus-doped polysilicon used as a gettering layer on the back-side of the wafer has provided the best results in terms of leakage-current and generation lifetime values.