Observation of Metal-free Phthalocyanine Adsorbed on SiC Reconstructed Surface

Abstract

Metal-free phthalocyanine (H₂Pc) has unique features, such as visible light absorption and excellent thermal and chemical stabilities, which render them applicable to organic electronic devices. However, the condition of the phthalocyanine (Pc) film affects the performance of these devices. Therefore, it is necessary to establish a control method for Pc adsorption and the thin-film growth. In the present study, we observed the electronic structures and morphology of H₂Pc structures adsorbed on reconstructed SiC surfaces using metastable atom induced electron spectroscopy, low-energy electron diffraction, and atomic force microscopy. The H₂Pc molecules were deposited on each SiC reconstructed surface (particularly graphene) until the H₂Pc thin film was formed. The molecular orientation of H₂Pc adsorbed on the graphene surface changed from a tilted structure to a flat-lying structure with the increase in the deposition time. As the amount of deposition increases, the H₂Pc molecules formed a thin film on the surface during the island growth. We further discuss the adsorption structure and the thin-film growth of the H₂Pc molecules with the increasing deposition time on the SiC reconstructed surface.