Optical characterization of fullerene films on flat and patterned semiconductor substrates
Abstract Comprehensive optical characterization of C 60 films on semiconductor substrates has been performed by means of ellipsometry, Raman and photoluminescence spectroscopy. The films have been prepared by the sublimation of C 60 in vacuum. The morphology of these films and the C 60 –substrate interaction were investigated by atomic force microscopy. Both flat and patterned wafers of Si, Ge, and InP have been used as substrates. It was found formerly that the strong interaction occurs between C 60 molecules and Si surface, and the C 60 films on patterned InP surface grow with grains arrayed in [0 1 1] and [1 0 1] perpendicular directions. Initial optical characterization was performed by means of ellipsometry to determine thickness and optical constants of the films. Raman spectra have been measured at room temperature under argon laser excitation. It was shown to be very useful for structural characterization and estimation of stress. Observed increase of Raman signal from patterned samples and its possible connection with surface enhanced Raman scattering effect are under discussion. Raman spectra and low temperature photoluminescence provide information on dimer formation and polymerization.