Dresden 2009 – wissenschaftliches Programm
DS 16.15: Poster
Dienstag, 24. März 2009, 09:30–12:30, P5
In situ and ex situ Ellipsometry and Reflection Anisotropy Spectroscopy of rare-earth-diphthalocyanine filmes — •Falko Seidel, Cameliu Himcinschi, and Dietrich R. T. Zahn — Technische Universität Chemnitz, Institut für Physik, Halbleiterphysik, D-09107 Chemnitz
Phthalocyanines are commonly known to possess semiconducting properties and are studied for there potential technical applications as organic semiconductors. Still only few publications cover rare-earth diphthalocyanines. Double-decker phthalocyanines like the here investigated LuPc2 may yield better properties for technical applications than the commonly studied ones. Almost all phthalocyanines form films with strong optical anisotropic if they are deposited on hydrogen passivated Si(111) substrates by sublimation in high vacuum. To measure the optical response Variable Angle Ellipsometry Spectroscopy (VASE) and Reflection Anisotropy Spectroscopy (RAS) are employed. Since optical properties can change throughout the growth process and chemical reactions may occur after the sample is removed from the vacuum in situ ellipsometry and RAS are far superior to their ex situ counterparts. For the evaluation of VASE data the program WVASE32 is used. Since LuPc2 does not possess the usual transparent region in the near infrared, special care is taken to evaluate the correct thickness. The high anisotropy of the layer allows to draw conclusions about the orientation of the molecules with respect to the substrate: mostly the Pc-rings are standing. With increasing thicknesses the line shape of the Q-band changes. Also electrochromical behaviour is observed.