Guided-Mode Resonance Enhanced Ge-on-Si Self-Powered Surface Illuminated Photodetector for Ultrahigh-Speed Optical Communication Systems

• Published in: IEEE sensors journal 2024-12, Vol.24 (24), p.40669-40677
• Main Authors: Lotfiani, Ahmad, DEHDASHTIJAHROMI, Hamed Dehdashti
• Format: Article
• Language: English
• Subjects: Absorption; Absorptivity; Arrays; CMOS; Communications systems; Dark current; Ge-on-Si photodetector; Germanium; high quantum efficiency; high speed; Near infrared radiation; normal incidence; Optical device fabrication; Optical devices; Optical sensors; Optical waveguides; Photodetectors; Photometers; Pins; Quantum efficiency; self-driven photovoltaic; Sensors; Silicon
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2024.3485510

Germanium-on-Silicon photodetectors offer complementary metal-oxide-semiconductor (CMOS) compatibility and ultra-fast response, making them attractive for silicon photonics in the telecommunication band (O-band, 1310 nm). However, their low absorption coefficient in the near-infrared region (NIR) limits quantum efficiency. Here, we propose a high-performance Germanium photodetector on silicon that addresses this challenge. Our design incorporates a self-driven photovoltaic structure with an ultra-thin (100 nm) Ge absorption layer and a strategically placed silicon nanodisk array. This nanodisk array efficiently couples light into the device, leading to a significantly enhanced light-matter interaction and a remarkable improvement in external quantum efficiency (EQE) (74%) and responsivity (0.78 A/W) at 1310 nm. Additionally, the device exhibits an exceptional response time of 1.4 ps and a high photo-to-dark current ratio ( 3\times 10^{{10}} ), demonstrating its suitability for high-speed NIR detection. The ultra-thin Ge layer and efficient light coupling pave the way for miniaturization and low-power operation, making this design promising for future high-performance NIR photodetectors.