Pentacene Thin Film Growth on Quartz and Mica

Organic thin films have gained significant attention due to their potential applications in organic electronics. Pentacene, a widely studied organic semiconductor, serves as a valuable model for investigating thin film properties. Nevertheless, its carrier mobility is highly influenced by molecular alignment, which, in turn, depends on the surface morphology of the substrate. In this study, we compare the growth of pentacene thin films on two well-defined substrates: mica, which is atomically flat, and quartz, which has step edges. Using thermal deposition, we cultivated pentacene thin films of varying thicknesses (0.8–40 nm) and analyzed their morphology using Atomic Force Microscopy (AFM). Our results show that the substrate's surface morphology strongly affects the film's growth mode. On quartz, pentacene follows an island-like Volmer-Weber growth mode, whereas on mica, it exhibits a 2D/3D Stranski-Krastanov growth mode. In addition, by correlating surface morphology with surface energy and contact angle measurements, we hypothesis that these two are key factors influencing the observed differences in island growth.