Hot Wall epitaxy of C-60 thin films on mica and their characterization

The growth of C-60 thin films on mica by Hot Wall Epitaxy was studied using high resolution X - ray diffraction. The influence of the Hot Wall source-, wall- and substrate temperature on the crystalline quality of the C-60 films was investigated by determining the full width at half maximum (FWHM) Delta omega of the C-60 - (111) reflex in omega - direction (i. e. rocking curve). With the optimal parameters of growth (substrate temperature = 140 degrees C, growth rate = 0.5 Angstrom/s) it is possible to grow 150 nm thick C-60 films with an omega - scan FWHM Delta omega of about 200 arcsec, the best value reported so far, indicating the growth of a perfect monocrystalline C-60 layer. Rocking curves of thicker films exhibit a complex shape, which is interpreted as a result of a change in the growth mode of C-60 films exceeding a critical thickness. In addition surface cracks appearing on the C-60 film surface are investigated using digital image processing. Atomic force microscopy- and photoluminescence measurements performed on the thin films complete this study.