Microscopic study of tunneling processes via localized states in amorphous-Si/SiOxtunnel barriers

Abstract

We report a detailed microscopic investigation of tunneling processes in a-Si/${\mathrm{SiO}}_{\mathrm{x}}$ barriers via localized states. In submicrometer a-Si/${\mathrm{SiO}}_{\mathrm{x}}$ tunnel junctions we observed a clear step pattern (quantum Ohm’s law) in the I-V curves, reflecting the discrete indirect (resonant) conductance channels via the individual localized states. We conclude that inelastic effects are crucially involved in such indirect tunneling processes. Furthermore we present evidence for a new threshold effect for the onset of the indirect tunneling, which may be due to Coulomb interactions with the metal electrodes.