Plasmon-enhanced Ge-based metal-semiconductor-metal photodetector at near-IR wavelengths
Mario Lodari (TU Delft - QCD/Scappucci Lab, IMAMOTER - C.N.R. Sensors and Nanomaterials Laboratory, Politecnico di Milano)
Paolo Biagioni (Politecnico di Milano, IMAMOTER - C.N.R. Sensors and Nanomaterials Laboratory)
Michele Ortolani (Sapienza University of Rome)
Leonetta Baldassarre (Sapienza University of Rome)
Giovanni Isella (IMAMOTER - C.N.R. Sensors and Nanomaterials Laboratory, Politecnico di Milano)
Monica Bollani (IMAMOTER - C.N.R. Sensors and Nanomaterials Laboratory)
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Abstract
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 µm, highlighting the potential of this approach for optoelectronic and sensing applications.
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