Secondary electrons induced by fast ions under channeling conditions. I. Production and emission of secondary electrons

Energy spectra of ion-induced secondary electrons emitted from Si and GaAs single crystals have been measured for various ions with a velocity of 3.75 MeV/amu. A simple ${\mathit{Z}}_1^2$-scaling behavior of the electron yields indicates that the observed keV electrons stem from simple binary collisions between the ions and the target electrons. Measurements for GaAs crystals preamorphized with 2-keV ${\mathrm{Ar}}^{+}$ ions provide evidence for the localization of the binary collisions near the surface region under channeling incidence conditions. Furthermore, these measurements are used to determine the effective target thicknesses both for channeling and random incidence conditions.