Surface Morphology of Pentacene Thin Film

Abstract

Growth mechanism of Pentacene thin film has been investigated with a combination of atomic force microscopy measurements and numerical modeling. Initially Pentacene grows as a monolayer fractal islands caused by DLA mechanism and evolves into compact islands as the surface coverage increases. As the branches of the first layer are widened, the monomer density on the top of the first layer increases and eventually becomes large enough to form critical islands for the growth of second layer. This phenomenon is mainly attributed to a growth instability caused by the Schwoebel barrier that prevents the newly landing molecules from hopping down the edge. Simulations based on a simple model of film growth are found to agree with experimental observations.