Achievement

Nanoantennas are key optical components for light harvesting; photodiodes convert light into a current of electrons for photodetection. We show that these two distinct, independent functions can be combined into the same structure. Photons coupled into a metallic nanoantenna excite resonant plasmons, which decay into energetic, “hot” electrons injected over a potential barrier at the nanoantenna-semiconductor interface, resulting in a photocurrent. This dual-function structure is a highly compact, wavelength resonant, and polarization-specific light detector, with a spectral response extending to energies well below the semiconductor band edge. The range of potential applications of this device concept is extremely diverse. As silicon based detector capable of detecting sub–band gap photons, this device could find use in on-chip silicon photonics, eliminating the need for additional semiconductor materials as detectors into chip designs, which would lower fabrication costs.