Morphology and characteristics of C60 thin films grown in argon atmosphere by thermal evaporation

The surface morphology, structure, and optical absorption characteristics of C60 thin films grown in argon atmosphere by thermal evaporation have been studied. X-ray diffraction studies reveal a mixture phase of face-centered-cubic and hexagonal-close-packed phases for this film. Infrared analyses show no evidence of chemical change. The observations of atomic force microscopy of C60 thin films grown in argon atmosphere found that surface particles are larger and sharper than that grown in vacuum, thus C60 thin films grown in argon atmosphere may be advantageous to using C60 for electron field emission. Ultraviolet-visible optical absorption spectrum of this film in the range of wavelength from 200 to 600 nm is very different than that of the film obtained under vacuum conditions. The position and intensity of absorption peaks are obviously changed compared to vacuum C60 thin film. The band gap energy of this film also changes from 2.02 to 2.24 eV compared to the film prepared under vacuum.