Enhanced electrical transport between the metal nano-particles by coveringof monolayer C-60

Electrical insulating metal granular films were prepared at room temperatur e and then C-60 molecules were slowly deposited on top of the metal films a t the same vacuum. In situ measurements of electrical conductivity were mad e during the deposition of C-60, and the results indicated that the conduct ivity depends on the thickness of C60 film Transitions of insulating-conduc ting-insulating were observed, and the maximum conductivity (sigma(max)) of the metal/C-60 films was measured when the coverage of C-60 is about one m onolayer. A possible explanation of this unusual conductivity enhancement p henomenon based on metal-fullerene charge transfer effect is discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.