SI-PIN X-RAY-DETECTOR TECHNOLOGY

PIN diodes and other test structures have been fabricated on both n- a nd p-type, high-resistivity, Floating-Zone (FZ) silicon substrates. Di fferent alternative extrinsic-gettering techniques have been adopted t o the purpose of meeting the required specification of a detector leak age current density lower than 1nA/cm(2). Phosphorus-doped polysilicon gettering provided the best results on n-type Si with a leakage curre nt density lower than 0.2nAcm(2) at 100 mu m depletion width. On the c ontrary, devices made on p-type substrates exhibited a leakage current density two orders of magnitude higher. A proper control of the oxide charge at the silicon-silicon dioxide interface was found to be cruci al in obtaining a predictable behavior of PIN diode detectors. Some de gradation of the reverse leakage current has been observed after devic e dicing and bonding.