Efficient nanoantenna simulation for IR energy harvesting and detection devices

A novel nanoatenna is designed for enhancing an IR energy harvesting device and realization of a focal plane array polarimetric IR detector. Instead of using a bulk semiconductor material for photovoltaic detection, the semiconductor p-n junction is scaled down and loaded at the antenna´s terminal where the antenna field enhancement can be utilized. For infrared (IR) devices, a low-band gap material, Indium Gallium Arsenide Antimonide (InGaAsSb) is used and its electrical properties are analyzed in order to optimize it as the antenna load. For maximum power transfer between the antenna and the load, the impedance matching is established by optimizing the antenna geometrical and material parameters as well as utilizing a reactive shunt transmission line stub. In numerical simulations, the Drude model for metal is incorporated in the FEM code to account for plasmonic effects. Also to match the antenna to high load impedance, the antenna is operated at its anti-resonance mode. It is shown that the antenna loaded with InGaAsSb can present a field enhancement as high as 23.5 in a near-IR band. The performance of the IR harvesting device in terms of absorption efficiency is enhanced by 50%. Also the detectivity of the uncooled-IR detecting device made by such antenna and load is improved by a factor equal to the field enhancement factor (~23).