Narrow-Band 4.3μm Plasmonic Schottky-Barrier Photodetector for CO2 Sensing

Using an embedded platinum silicide (PtSi) grating, a Schottky-barrier photodetector structure for narrow-band detection of mid-infrared (mid-IR) radiation is proposed and designed. Schottky-barrier photodetectors designed for the infrared wavelengths suffer from poor efficiency and photoresponse. We propose a photodetector based on PtSi-Si Schottky junction with increased interface area where hot carriers are more likely to cross the junction in favor of a higher photoresponse. Furthermore, a guided-mode resonance of the presented periodic structure is coupled to its Fabry-Pérot resonance to achieve narrow-band absorption. The proposed photodetector absorbs 84% of incident power at a wavelength of 4.3 μm with a full-width half-maximum bandwidth of 94 nm. High photoresponsivity and compatibility with complementary metal oxide semiconductor process render the proposed structure a low-cost photodetector in the mid-IR range for CO
₂
sensing.