Conduction mechanism in vanadium pentoxide xerogel films

Abstract

The time dependence of the d.c. conductivity and the current-voltage characteristics of vanadium pentoxide xerogel films of thicknesses ranging between 5 and 1 000 nm have revealed that the conduction in this system is purely electronic. From 1/f-noise measurements an upper limit of 10^17 to 6 × 10^18 cm-3 for the charge carrier concentration could be estimated which showed weak thickness dependence. These figures are approx. two orders of magnitude higher than those of single crystal V2O 5, and also two orders of magnitude lower than the V4+ concentration in either the films or the single crystals. This suggests that the higher conductivity of xerogels is associated with film hydration which increases the number of V4+ sites active in the conduction process.