Interaction of keV ions with insulator films at grazing incidence: growth characterization and electron emission

E.A. SANCHEZ; G. OTERO; N. TOGNALLI; O. GRIZZI; V.H. PONCE

NUCLEAR INSTRUMENTS AND METHODS IN PHYSICS RESEARCH B - BEAM INTERACTIONS WITH MATERIALS AND ATOMS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2003 vol. 203 p. 41 - 48

0168-583X

We present a study of the growth of AlF3 thin films on Al(1 1 1) surface, together with the electron emission produced in the scattering of 60 keV protons from these films. The growth of the AlF3 films at room temperature, from submonolayer coverage up to several layers, was characterised by means of Auger electron spectroscopy and electron energy loss spectroscopy. We found that from the beginning of the evaporation the AlF3 molecules adsorb stoichiometrically, and layer-by-layer. The electron emission induced by grazing proton bombardment was measured as a function of the film thickness. In the forward direction, the most prominent structure can be related with convoy electron emission. For the case of the metallic surface, the maximum of this peak is located at energies above the corresponding one to electron transfer to projectile continuum states in gas-phase collisions, and shifts to lower values for sufficiently thick films. This result is discussed in terms of the competition between track and polarisation potentials generated in the insulator film, and image potentials induced in the metallic substrate