High-energy particles incident to a semiconductor sensitively produce electron-hole pairs and the excited current has been used for radiation detectors. Although semiconductors have advantages such as high sensitivity and fast response, a drawback is weakness in radiation damage. To improve the radiation resistance, effects of shallow-impurity doping was explored for Si. Specimens of CZ-Si doped with P or B were bombarded with 17 MeV protons. The radiation-induced current of doped Si has been evaluated, as a function of proton fluence. The sig:sal of particle-induced conductivity showed a fairly constant response to a proton flux, up to 10(15) ions/cm(2). The fluence range applicable as Si sensors was extended 10(3)-10(4) times as much as that of non-doped Si, instead of a lower signal-to-noise ratio. Shallow impurities passivate the deep centers of radiation-induced defects, and the radiation tolerance continues until the pre-existent carriers are exhausted. The tolerant fluence is also usable to detect the integrated fluence, by controlling the initial impurity concentration.
