Premium
Aging‐induced optical anisotropy in thermally grown thin Zn TPP films on Si
Author(s) -
Kate Stephan Peter,
Pop Simona,
Esser Norbert,
Rappich Jörg,
Zhang Xin,
Hinrichs Karsten
Publication year - 2013
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201248538
Subject(s) - anisotropy , spectroscopy , materials science , thin film , porphyrin , silicon , absorption spectroscopy , tetraphenylporphyrin , absorption (acoustics) , analytical chemistry (journal) , photochemistry , chemistry , optics , optoelectronics , nanotechnology , organic chemistry , physics , quantum mechanics , composite material
We present reflection anisotropy spectroscopy (RAS) as a powerful optical technique for degradation studies of structurally changing thin organic films, here the case of porphyrin films. The measured optical anisotropy of a thin ( d = 16 nm) ZnTPP (Zinc tetraphenylporphyrin) film grown by thermal evaporation on silicon using reflectance anisotropy spectroscopy was studied before and after aging in ambient conditions. The observed absorption features, also found by standard transmission spectroscopy, are correlated with the π–π* electronic transitions of the Q and Soret bands of the molecule. Simulation of RAS spectra revealed blue‐shifted resonances, which are in agreement with a preferential face‐to‐face (stacking) arrangement of the ZnTPP molecules. The findings are in agreement with atomic force microscopy studies of the surface morphology showing with aging a transition from a closed film to separated aggregates.