; MORPHOLOGY AND THERMAL STABILITY OF THIN AlF3 FILMS ON Cu(100)

G.RUANO; J.MORENO; M.PASSEGGI; J. FERRON; M.A.NIÑO; R.MIRANDA; J.J.DEMIGUEL

Edimburgo

Conferencia; CMD-24 (ECOSS-29, CMMP-12, ECSCD-11); 2012

The growth and thermal stability of thin AlF3 films grown on Cu(100) have been studied by a combination of surface science techniques. AlF3 is an interesting material for many applications; it is a wide band-gap insulator (10.8 eV), transparent in the visible range and chemically inert, what makes it a good passivating agent. Furthermore, it can be easily decomposed by electron irradiation leaving deposits of metallic Al, which can be taken advantage of for ebeam nanopatterning purposes. STM measurements show that the growth of AlF3 on Cu at room temperature starts with the decoration of the substrate atomic steps followed by the formation of 2-dimensional dendritic islands that coalesce to form porous layers. STM and thermal energy atom scattering (TEAS) also reveal that films with thicknesses below 2 ML are morphologically unstable upon thermal treatments: when heated up to 430 K these layers de-wet the substrate and form three-dimensional islands. On the contrary, thicker films are stable up to 730 K, where desorption in molecular form starts taking place. The effect of electron irradiation has also been characterized by means of surface spectroscopies. It is shown that even very small doses of electrons are enough to provoke the decomposition of the aluminum fluoride and the release of molecular fluorine.