Energy Spectra of Displaced Atoms in High-Energy Electron-Irradiated Si: Views on Electron Beam Doping and Damage Factor

Abstract

Electron energy spectra as a function of depth have been computed by means of a Monte Carlo simulation for Si samples with a diameter of 20 µm irradiated by electron beams at 2 to 9 MeV. The energy spectra of primary displaced atoms were calculated from the electron energy spectra and found to be similar to the electron energy spectra. Values of the average energy transfer at the peak of the spectra at a normalized depth of 0.1 (=z/R), where z is depth from the Si surface and R is range of electrons, are about 53, 82, 108 and 120 eV for 2, 4, 7 and 9 MeV electron beams, respectively. It was suggested that the displaced atoms with effective average energy transfer were produced, which contributed to the electron beam doping. There is a proportional relationship between the measured damage factor and nonionizing energy loss, calculated based on respective depths of Si sample irradiated by electrons.