Nanoscale observation of interface formation process between semiconductor surface and pentacene thin film

Interface formation process of pentacene thin films on semiconductor surfaces has been studied using low energy electron microscopy (LEEM) and scanning tunneling microscopy. Interface interaction between clean Si surface and pentacene film is optimized by inserting bismuth thin film at the interface, resulting in the formation of monolayer islands larger than 0.2 mm in diameter. Systematic surface reactivity control on Si substrate reveals that the surface states nearby the Fermi level are the origin of the interface interaction between pentacene molecules and semiconductor surfaces. Effect of kinetic growth process on the pentacene film growth is also examined by detailed LEEM observations. The anisotropic growth speed originating from the anisotropic structure of pentacene accompanied with the kinetic growth condition could result in the formation of textured structure inside the single grain grown from a single nucleus.