Theoretical analysis and fabrication of small area metal/insulator resonant tunneling diode integrated with patch antenna for terahertz photon assisted tunneling

Abstract

Alternative voltage induced across a resonant tunneling diode under the THz radiation, which is an important factor for photon assisted tunneling, is theoretically analyzed in general form. As an application, integration of a small-area resonant tunneling diode with a circular patch antenna is proposed. A patch antenna has high radiation directivity and suitability for a diode with vertical layer structure on a high-doped substrate. Size of the antenna and diode necessary to reduce the loss and capacitance was discussed taking into account fabrication limit. The estimated voltage in this integrated device together with an appropriate lens system is comparable to the THz photon energy under relatively low power radiation (∼100 mW). To achieve requirement of the device size, a fabrication process is investigated for a 1 mm-diameter metal/insulator (CoSi 2/CaF 2) resonant tunneling diode with a patch antenna. Fabricated diodes show negative differential resistance in static characteristics with the maximum peak-to-valley ratio of 2.8 at room temperature.