| Home > Comparison between nucleation of pentacene monolayer islands on polymeric and inorganic substrates |
We present a comparative study of the nucleation and growth of pentacene monolayer islands in the submonolayer regime onto inorganic substrates of SiO<sub>2</sub> and sapphire (Al<sub>2</sub>O<sub>3</sub>) and organic substrates of poly(methyl-metacrylate) (PMMA). We have determined the scaling laws that govern the saturated nucleation density per unit area N as a function of two essential deposition parameters: the deposition rate κ and the substrate temperature T<sub>s</sub>. For all substrates, we found N∝κ<sup>δ</sup>, with 0.8⩽δ⩽1.2, and the T<sub>s</sub> dependence of the nucleation density follows a typical activated Arrhenius law. Whereas a critical nucleus size of i=2 is obtained for all investigated substrates, the activation energy for nucleation depends significantly on the dielectric. The difference in activation energy of nucleation on PMMA and SiO<sub>2</sub> is due to different molecule-substrate interactions