GROWTH OF PB-PHTHALOCYANINE THIN-FILMS ON MOS2 SURFACES STUDIED BY MEANS OF LOW-ENERGY-ELECTRON TRANSMISSION SPECTROSCOPY

Low-energy electron transmission (LEET) spectroscopy was used to study the growth of Pb-phthalocyanine (PbPc) thin films on MoS2 single crys tal surfaces. We observed LEET features typical of the ultrathin films which were prepared by direct molecular-beam deposition of PbPc molec ules as well as by thinning thicker films by heat treatment. The depen dence of the work function of the film on the film thickness gave a mi nimum value for the ultrathin films which exhibit LEFT features differ ent fiom those for thicker films. The results indicate that the ultrat hin film consists of a monolayer of PbPc molecules and LEET spectrosco py is useful in observing monolayer growth of functional organic molec ules. Furthermore, the effects of heat treatment and aging of the PbPc films are investigated.