Radiation-resistant photoconductivity of doped silicon under 17 MeV proton bombardment

Irradiation performance of Si has been investigated under 17 MeV proton bombardment. Radiation-resistant photoconductivity (PC) of crystalline Si has been attained by shallow impurity doping, in a concentration range of 10(14)-10(16) cm(-3). The band-to-band PC is stable, unless the doped carriers are exhausted by defect trapping. The PC fluence dependence shows two-step variations in photo- and dark conductivity. The PC method reveals a quantitative relation between primary and residual defects. The real-time measurement also reveals correlation between proton-induced electronic excitation and photoconductivity. Though the PC fluence dependence at low fluences is similar to the electron data, the PC drop for the proton is more severe at higher fluences, i.e., stronger capture efficiency than the electrons, because of cascade effects. Although the shallow impurity doping worsens the unirradiated PC sensitivity, stability under irradiation significantly improves. The photoconductivity of doped Si is applicable for radiation-resistant optical devices by the aid of phase-sensitive AC detection.