Structural characterization of iron phthalocyanine thin films by X-ray diffractometry

The crystal structure of iron phthalocyanine (FePc) thin films was investigated by X-ray diffractometry (XRD) as a function of deposition temperature and \textit{in situ} annealing. FePc was deposited on A-plane sapphire in an organic molecular beam epitaxy (OMBE) system equipped with a low temperature effusion cell. The pressure of the OMBE was better than 5x10$^{-9}$ during deposition. The substrates were held at constant temperatures ranging from ambient to 300 $^{o}$C during deposition. For each substrate temperature, post-deposition \textit{in situ} annealing at the same temperature was performed for 1, 2, 4, and 8 hours. XRD analysis shows that films were grown to $\sim $10 monolayers thick with 1-2 monolayers of roughness. XRD also reveals the emergence of higher order peaks as deposition temperature increases. Supporting AFM results show improvement toward the deposition of pinhole-free FePc films. OMBE grown films are compared to others deposited using a simple thermal evaporator with a deposition pressure of $\sim $10$^{-7}$ Torr.