We propose a plasmonic gold nanodipole array on silicon, forming a Schottky contact thereon, and covered by water.
The behavior of this array under normal excitation has been extensively investigated. Trends have been found and
confirmed by identification of the mode propagating in nanodipoles and its properties. This device can be used to detect
infrared radiation below the bandgap energy of the substrate via internal photoelectric effect (IPE). Also we estimate its
responsivity and detection limit. Finally, we assess the potential of the structure for bulk and surface (bio) chemical
sensing. Based on modal results an analytical model has been proposed to estimate the sensitivity of the device. Results
show a good agreement between numerical and analytical interpretations.
Metallic nanowires of rectangular cross-section can operate as isolated or arrayed optical monopole or dipole antennas, and when deposited on a Si substrate and covered with water, become useful as (bio)chemical sensors. The optical performance of such antennas is assessed over a broad wavelength range as a function of geometrical parameters, including wire thickness, width, length, and gap (in the case of dipoles). Effects caused by varying the pitch of twodimensional arrays of antennas are also determined. Given a uniform broadside excitation, antennas resonate in the main mode of propagation of the corresponding asymmetric metal stripe waveguide, and antennas performance is related to its propagation characteristics. The structures considered are amenable to fabrication via metal evaporation and lift-off, with the nanowires defined by electron beam patterning.