Effect of ultrathin gold on the Ohmic-to-Schottky transition in Al/ZnO contacts: A first-principles investigation

By using a first principles approach based on Density Functional Theory, we present a study of the manipulation of the Al/ZnO contact, which may be turned from Ohmic to Schottky by simply including an ultrathin Au interlayer at the interface. To understand the rationale behind this contact design, we first characterize the original Al/ZnO interface, which results to be Ohmic, irrespective of the substrate termination and of eventual n-doping. Then, we identify the mechanisms that regulate the contact behavior switch upon gold insertion by highlighting the different charge transfer processes that take place at the interface.