Plasmon-enhanced Ge-based metal-semiconductor-metal photodetector at near-IR wavelengths

We demonstrate the use of plasmonic effects to boost the near-infrared sensitivity of metal-semiconductor-metal detectors. Plasmon-enhanced photodetection is achieved by properly optimizing Au interdigitated electrodes, micro-fabricated on Ge, a semiconductor that features a strong near IR absorption. Finite-difference time-domain simulations, photocurrent experiments and Fourier-transform IR spectroscopy are performed to validate how a relatively simple tuning of the contact geometry allows for an enhancement of the response of the device adapting it to the specific detection needs. A 2-fold gain factor in the Ge absorption characteristics is experimentally demonstrated at 1.4 mu m, highlighting the potential of this approach for optoelectronic and sensing applications. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement