ELECTRONIC PROPERTIES OF THIN FILMSSUBLIMED FROM La@C_(82)AND Li@C_(60)

摘要

La@C_(82)and Li@C_(60)thin films obtained by sublimation in vacuum are studied using four-probecurrent–voltage measurements and atomic force microscopy. In situ electrical measurementsshow semiconducting behavior of both films with room-temperature resistivity of 21 ± 8 and1230 ± 50 C2 · cm for the La@C_(82)and Li@C_(60), respectively. A variable range hopping mechanismof conductance is suggested from the temperature dependences of resistance. The activationenergies for electron transport are calculated for both metallofullerenes. Irreversible changes tothe Li@C_(60)film structure increasing the resistivity to values typical forC60are found atelevated temperatures. The effect of exposure to ambient atmosphere on the conductance of thefilms is discussed.