ROOM-TEMPERATURE CONDUCTANCE QUANTIZATION IN V-VERTICAL-BAR-AMORPHOUS-V2O5-VERTICAL-BAR-V THIN-FILM STRUCTURES

With a parallel component removed, the room temperature conductance of V\amorphous-V2O5\V sandwiches at low voltages (8<qV/kT<15) is stepped at discrete values G=2ie2/h, where h is Planck's constant, e is the e lectron charge, and i is the integer or half-integer. In contrast with similar results reported by J. Hajto, M. J. Rose, A. J. Snell, I. S. Osborne, A. E. Owen, and P. G. LeComber [J. Non Cryst. Solids 137-138, 499 (1991)] conductance quantization was observed without electroform ing at high voltages. The results suggest that a ballistic point conta ct was formed in the nonmetal-metal interphase either by a laterally u nstable contact reaction during deposition, or by electronic injection at low bias voltage. The onset of conductance quantization at a highl y characteristic threshold voltage favors the latter.