Influence of ionic interfacial layers on electronic properties of Alq3/Si(100) interface

The electronic structures of Alq₃/Si(100), Alq₃/LiBr/Si(100), and Alq₃/KCl/Si(100) systems are presented in this report. Their energy level diagrams were prepared and discussed. The formation of the LiBr and KCl interfacial layers between an Alq₃ film and a Si(100) substrate results in a decrease of the energy barrier at the interface. The studies were carried out in situ in ultrahigh vacuum by ultraviolet photoelectron spectroscopy. Alq₃ as well as LiBr and KCl layers were vapour evaporated onto n‐type Si(100) crystal. The electron affinity of clean Si(100) surface was 4.0 eV, and the position of the valence band maximum was 0.7 eV below E_F. The energetic distance between the valence band maximum of Si(100) and the highest occupied molecular orbital level were 1.5, 2.6, and 2.2 eV, for the Alq₃/Si(100), Alq₃/LiBr/Si(100), and Alq₃/KCl/Si(100) systems, respectively.