Tunable Plasmonic Resonances Below Schottky Diode Band-gap Based on Elliptical Nanoantennas

Nanoantennas are suitable components for detection of optical radiation at energies below the bandgap energy of the semiconductor and higher than Schottky barrier of metal/semiconductor interface in photodetectors. Elliptical nanodisk antennas (ENAs) on a Gallium Arsenide (GaAs) substrate are studied to tune the optical response across the near-infrared band. The resonance wavelength, normal field enhancement, and bandwidth of plasmonic resonance are tailored by controlling the size and elliptical aspect ratio. The results are compared with circular nanodisk antennas (CNAs) and ring nanoparticle antennas (RNAs). Silver and gold metal types for nanoantennas are also studied for electric field enhancement, where the Drude model of metals are considered. The surfaces plasmon is proven by comparing with the perfect electric conductor of silver and gold nanoantennas. The obtained results prove that the designed nanoantennas can be used to enhance the operation of photodetectors and solar cells.