The chemisorption of tetracene on Si(100)-2x1 surface

The adsorption of tetracene on Si(100)-2x1 substrate has been studied by ultraviolet photoemission spectroscopy (UPS). Six features deriving from the organic material are located at 1.22, 2.41, 3.63, 4.67, 7.11, and 8.77 eV below the Fermi level. These features shift in binding energy with increasing the thickness of the organic film. In the case of a monolayer, angle-resolved UPS measurements suggest that the molecular plane is parallel to the substrate. Further theoretical density functional theory calculation reveals the most stable structure of tetracene molecule on Si substrate in which six covalent Si-C chemical bonds are formed between carbon atoms of the tetracene molecule and the Si atoms on the substrate.