Negative differential resistance in electrochemically self-assembled layered nanostructures

Resonant tunneling devices are used for ultrahigh-speed applications. In th is work, tunnel junctions based on copper metal (Cu) and cuprous oxide (Cu2 O) are electrochemically self-assembled from aqueous solution in an oscilla ting system. The Cu2O layer thickness (L) is tuned from 0.8 to 2.8 nm by si mply changing the applied current density. The layered structures show shar p negative differential resistance (NDR) signatures at room temperature in perpendicular transport measurements, and the NDR maximum shifts to higher bias with a 1/L-2 dependence as the Cu2O layer is made thinner. The results are consistent with resonant tunneling from Cu into hole states in the val ence band of quantum-confined Cu2O through thin space-charge regions on eac h side of the Cu2O.