Homoepitaxy Growth of Well-Ordered Rubrene Thin Films

Abstract

Rubrene is a nonplanar molecule, it is recognized that only amorphous rubrene films can be obtained on such substrates as Au, SiO2, and Al2O3 by organic molecular beam deposition or ordinary vacuum evaporation. In this work, rubrene organic single crystals with very smooth surfaces were used as substrates. Well-ordered rubrene thin films were obtained by ordinary vacuum evaporation, and the substate temperature is room temperature. Two-dimensional nucleation-monolayer by monolayer growth and homoepitaxy was demonstrated when the deposition rate was kept at 0.2 nm/min. Furthermore, when the deposition rate was increased to 0.6 nm/min, two-dimensional hexagons were observed in the growth process of rubrene thin films and are similar to the two-dimensional islands with regular shapes observed in homoepitaxy growth of inorganic thin films.