Thermal fluctuation-induced tunneling conduction through metal nanowire contacts

Abstract

The temperature behavior of how electrons propagate through an insulating electroniccontact formed at the interface between a submicron Cr/Au electrode and a metallicRuO2 nanowire (NW) has been studied between 300 and 1 K. The NWs are typically of∼70 nm in diameter and a few microns long. The submicron electrodeswere fabricated by the standard electron-beam lithography technique.By employing the two-probe method, the electronic contact resistances,Rc(T), have been determined. We found that, in general,Rc increases rapidly with decreasing temperature but eventually saturates atliquid-helium temperatures. Such a temperature behavior can be well describedby a thermal fluctuation-induced tunneling (FIT) conduction process whichconsiders the crossover feature from thermal activation conduction at hightemperatures to simple elastic tunneling conduction at low temperatures. The wideapplicability of this FIT model has further been established by employing metallicIrO2 andSn-doped In2O3−x NWs. This work demonstrates that the underlying physics for the charge transportproperties of an insulating electronic contact can be well understood.