[17p-F104-1~16] 12.2 Characterization and Materials Physics

[17p-F104-16] Low-energy electron diffraction study of adsorption state of phthalocyanine molecules on In/Si(111)

〇Shinichiro Hatta¹, Haruna Aya¹, Hiroshi Okuyama¹, Tetsuya Aruga¹ (1.Kyoto Univ.)

Keywords:organic thin film, electron diffraction

We have investigated self-assembly of copper phthalocyanine (Pc) molecules adsorbed on the Indium-covered Si(111) substrate by low-energy electron diffraction (LEED) and a four-point probe method for electrical conductivity measurement. We found coverage-dependent and temperature-dependent change of LEED patterns in the submonolayer regime. While molecules are self-assembled to form a (4 1| 1 4) superstructure with a approximate square lattice at lower temperature or higher coverage, it shows a ring pattern at higher temperature or lower coverage, indicating a 2D gas phase. We confirmed that the temperature-derived transition is reversible unless samples are heated above ~330 K. The irreversible change of the molecular layer caused decrease of electrical conductivity, which suggests chemical reaction between Pc molecules and the substrate.