Photoelectron Spectroscopy Study of the Electronic Structures of Al/MgF2/tris-(8-hydroxyquinoline)aluminum Interfaces

Abstract

We have studied the electronic structures of Al/MgF₂/tris-(8-hydroxyquinoline)aluminum (Alq₃) interface using UV and X-ray photoelectron spectroscopy (UPS & XPS). The UPS revealed that the valence peak shift occurred with MgF₂ deposition before Al was deposited and was independent of the gap state formation. The XPS core level peaks indicated that the MgF₂ strongly interacted with Al and O atoms in Alq₃ even before Al was deposited, and the deposition of Al caused slight change to the N 1s core level peak. These results indicate that the interaction mechanism in Al/MgF₂/Alq₃ is different from those found in Al/LiF/Alq₃ and other metal/Alq₃.