Fermi and anti-Fermi glass transition and subband resonant quantum tunneling in Nb/Ti metallic multilayer films

Abstract

Multilayer of Nb/Ti and NbN/Ti films with 30 periodic structure were sputtered onto silicon substrates. The current-voltage characteristics measured along the vertical junction at low temperatures exhibit nonlinear step-wise curves. The resonant subband quantum tunneling in the metallic multiple quantum wells can satisfactorily express these peculiar behaviors. The Fermi and anti-Fermi glass transition showing itinerant metallic and insulating conduction properties are also observed at low currents and near critical temperatures.