Particle-induced conductivity and photoconductivity of silicon under 17 MeV proton irradiation

Particle irradiation, as well as light illumination, to semiconductors increases electric conductivity. The particle-induced conductivity (PIC) of Si, under 17 MeV proton irradiation, has been studied measuring the dependence on proton fluence and flux. While the PIC of undoped Si rapidly deteriorates with proton fluence, that of doped Si does not greatly decrease below a certain fluence phi(C) and steeply decreases above the fluence. The results are compared with photoconductivity (PC) in response to near-infrared light. The fluence dependence of the PIC is similar to that of the PC. The specific fluence phi(C) coincides with the critical fluence in the PC evolution which we previously reported. The PIC is proportional to the square root of proton flux, while the PC follows a linear relation to the photon flux. Although the proton irradiation causes high-energy synergistic processes, the PIC is dominated by electron-hole production due to proton excitation. The PIC processes are elucidated in a similar manner to the PC processes, taking into account the stronger electronic excitation of the protons than that of the photons. (C) 1998 American Institute of Physics. [S0021-8979(98)07621-X].