Metal phthalocyanines (MePc) have unique features applicable to the field of electronics and optics. In this study, we observe the surface electronic structure of MePc (Me = Cu, Zn) adsorbed Si(100) using metastable-atom induced electron spectroscopy (MIES). MePc molecules are deposited for less than 2000 s in vacuum at room temperature. At the initial adsorption of the MePc, each molecule lays flat on the substrate and the center metal atom is on top. This orientation of the adsorbed molecules gradually changed with an increase in the deposition time of the MePc. When the MePc covered surface was annealed by direct current heating at 800• C or below, the molecules started to decompose and desorbed from the Si(100) surface. However, Cu atoms remained on the surface. We discuss the adsorption structure based on the deposition time and behavior of the MePc molecule with annealing.

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