Ion-induced electron emission from Si crystal targets covered with noncrystalline Si layers

Ion-induced electron emission has been studied for Si crystal targets bomba rded by similar to 100 keV/u H+, He+, and 3.5 MeV/u O8+. Under channeling i ncidence conditions, we have measured the dependence of the continuum elect ron yield on the thickness of an overlaid noncrystalline Si layer which inc reases the number of unshadowed atoms near the crystal surface. The electro n yields in the channeling and nonchanneling cases are successfully account ed for using the two parameters determined from the experiments, i.e., the effective target thickness associated with the high-energy shadowing effect mainly on Si L-shells and the effective escape length for the electron yie ld. (C) 2000 Elsevier Science B.V. All rights reserved.