Numerous studies on metal-doped C-60 compounds had been done since the
discovery of superconducting C-60 compounds. It is interesting to stu
dy physical properties of trivalent-meta-doped C-60. We examined La-do
ped C-60 thin films fabricated by layer-by-layer (LBL) deposition with
a multi-source evaporation system. The physical properties of LaxC60
depend on the diffusion of La atoms in the film, so we studied the eff
ect of annealing. The crystal structure and morphology of LaxC60 thin
films were examined by X-ray diffraction and AFM and electronic struct
ure was also examined by UPS. We found that annealing promotes orienta
tion of the crystal. UPS spectra showed the change depends on the conc
entration of La atoms. Moreover, the spectrum of annealed thin film wa
s quite different from that of as-deposited thin film. (C) 1998 Publis
hed by Elsevier Science S.A. All rights reserved.