Design and Characterization of 28 THz Rectenna for Infrared Energy Harvesting

Abstract

The increasing energy demands of the world’s population and the quickly diminishing fossil fuel reserves together suggest the urgent need to secure long-lasting alternative and renewable energy resources. Infrared (IR) energy harvesting from waste heat can be a promising contribution for sustainable energy. In this talk, we will present a THz antenna integrated with rectifier (rectenna) for harvesting IR energy. The implementation of rectennas for energy harvesting at IR frequencies has remained an elusive research area due to the limitations of nano-scale fabrication and the inability to implement rectifiers that could handle electromagnetic (EM) radiation oscillating a trillion times per second. We will present the design of a resonant bowtie nanoantenna that has been optimized to produce highly enhanced localized fields at the bow tip. The phenomena of plasmon oscillation and hot spot creation at the feed point of the nano-antenna as a result of incident IR energy have been studied through EM simulations and Electron Energy Loss Spectroscopy (EELS). For the rectifier to function at THz frequencies, Metal-Insulator-Metal (MIM) diode has been realized because of its fast response time. To benefit from the field enhancement in the nano-gap, the diode is realized between the overlapped antenna’s arms using a 0.7 nm copper oxide. The thin film diode offers low zero bias resistance of 500 $\Omega$, thus improving the impedance matching with the antenna. In addition, the rectenna prototype demonstrates high zero bias responsivity (4 A/W), which is critical in producing DC current directly from THz signals without the application of an external electric source, particularly for energy harvesting applications. Finally, a new concept of geometric diode will be presented which can also work for THz frequencies.