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

Abstract

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 Alq 3 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. Alq 3 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 Alq 3 /Si(100), Alq 3 /LiBr/Si(100), and Alq 3 /KCl/ Si(100) systems, respectively.