Sodium (Na)-doped C-60 thin films were grown by using a high vacuum evaporation system. Ultraviolet photoelectron spectroscopy showed that the electronic density of states (DOS) of Na-doped C-60 films is higher than that of undoped C-60 films at 0-0.1 eV and 0.7-13.7 eV binding energy. We consider that the high electronic DOS near Fermi energy due to the Na-dopants contributes to the n-type semiconductor properties with electrical resistance of 1.5 x 10(5) Omega. We also observed that the electronic DOS of the C-60 films/CU substrate near Fermi level is higher than that of the C-60 films/Si substrate indicating charge transfer at the interface. (c) 2008 Elsevier B.V. All rights reserved.