Ion-beam-induced surface damages on tris-(8-hydroxyquinoline) aluminum

Surface damage of tris-(8-hydroxyquinoline) aluminum (Alq(3)) film by 100 e V Ar+ irradiation has been studied by using both x-ray and ultraviolet phot oelectron spectroscopies (XPS and UPS). XPS core level electron density cur ves revealed that some N-Al and C-O-Al bonds in Alq(3) molecules were broke n by the irradiation. Correspondingly, the valence band structure of the Al q(3) molecule, as measured by UPS, was tremendously changed. The highest oc cupied state extended towards the Fermi level (E-F), implying that a metal- like conducting surface was formed. This kind of damaged surface would caus e nonradiative quenching in an electroluminescence device when electrons ar e injected from the cathode into the Alq(3) layer, and possibly result in e lectrical shorts. (C) 1999 American Institute of Physics. [S0003-6951(99)00 237-5].