Infrared rectification based on electron field emission in nanoantennas for thermal energy harvesting

A rectification concept based on field electron emission in a nanoantenna is proposed. The device consists of three parts, i.e., an aspherical micro-lens, a nanoantenna, and an electron collector electrode with proper geometry design to ensure rectified field electron emission. The incident radiation is enhanced in two steps, firstly by micro-lens focusing onto the nanoantenna, and secondly through excitation of the near field in the gap of the nanoantenna to reach a level required for field electron emission from a sharp metallic tip. Furthermore, we show that single nanoantenna cells can be arranged into an array using a bus-bar configuration where the currents of each cell are added up to increase the harvested power. The performance of the nanoantenna in a single cell and in the array is studied by full-wave simulations. Finally, the total efficiency of the proposed device is calculated to demonstrate its superiority over the MIM devices.