On electrors-beam-induced charging effects in Cu- and Y-deposited LaAIO3surfaces

Electron-impact experiments on insulator and wide-band-gap semiconductor surfaces are disturbed by charging effects, particularly in cases of stoichiometric surfaces. We have studied the shift in kinetic energy of Auger electrons from 1 X 1 LaA103 100) surfaces as a function of Cu coverage, time of electron-beam bombardment, heat treatment, and—also for an Y deposited 1X 1 LaA103 100) surface—of primary beam energy. The energy shift is found to increase with metal coverage and with primary beam energy. It is suggested that at a particular energy the incident electrons result in a repulsive potential from which escaping Auger electrons gain kinetic energy, and that the initially deposited metal atoms may cause moving of electrons into valence-band states created by hybridization of surface metal and oxygen states. For comparison, the energy shifts in nondeposited LaA103100), MgO(lOO), and SrTiO3100) were also investigated.