Engineering the directionality of hot carrier tunneling in plasmonic tunneling structures

Tunneling metal-insulator-metal (MIM) junctions can exhibit an open-circuit photovoltage (OCPV) response under illumination that may be useful for photodetection. One mechanism for photovoltage generation is hot carrier tunneling, in which photoexcited carriers generate a net photocurrent that must be balanced by a drift current in the open-circuit configuration. We present experiments in electromigrated planar MIM structures, designed with asymmetric plasmonic properties using Au and Pt electrodes. Decay of optically excited local plasmonic modes preferentially creates hot carriers on the Au side of the junction, leading to a clear preferred directionality of the hot electron photocurrent and hence a preferred polarity of the resulting OCPV. In contrast, in an ensemble of symmetric devices constructed from only one Au, polarity of the OCPV has no preferred direction.

Automated summary

Tunneling metal-insulator-metal (MIM) junctions can exhibit an open-circuit photovoltage (OCPV) response under illumination, with hot carrier tunneling as one mechanism for photovoltage generation. In experiments conducted on electromigrated planar MIM structures with asymmetric plasmonic properties using Au and Pt electrodes, it was found that optically excited local plasmonic modes preferentially create hot carriers on the Au side of the junction, leading to a preferred directionality and polarity of the hot electron photocurrent and resulting OCPV. In contrast, symmetric devices with only one Au electrode do not exhibit a preferred direction of the OCPV.